All right, okay. So, safeguarding your website, smart WordPress security. Let's talk about it. Now, I'm curious because before we get into it, it's very important to understand where we all are as a group at our WordPress level. So you don't all have to speak at once. I would appreciate it if you would add in the chat. What is your WordPress level? Are you a beginner? Are you an intermediate user? Are you an advanced user? Because that'll let me know how do I tailor the conversation and make sure that we are all talking about the most important WordPress security measures. So we have Rick, a bit of a beginner, okay. Let's get beginner as well. I'm assuming when we say beginner, we're talking about like just started on using WordPress or about one to two years in that kind of a beginner. I'm assuming that sometimes it does take a little bit of a little bit of time to get used to WordPress is a very complex system. And that's the reason why this is important as far as security wise, because you definitely want your website, all that hard work you put in, you want to make sure your website is secure. Okay. Okay, Karen the beginner first year. Is it Lance is a middle Ellis a year in. Okay, okay. So we're we got a lot of people here, if not most that are of a year or so in. First of all, I'm asking that question because I want to reassure you right and really get rid of the whole myth if you don't already know that WordPress isn't secure. There's a lot of people out there, especially competitors that try to say WordPress is hacker prone and isn't secure and you can, and that's just not true. There are many things that we're going to talk about today that make sure website more secure, but WordPress itself is a very secure content management system. So I just want to move that whole mess out the way we go move it to the side, so that way we can get the myth. Over and done with WordPress is secure. However, there are things that can happen that there are ways that you can be compromised right that you can avoid by using some of these strategies and tactics that we're going to talk about today. So the first and one of the most important, I would say factors and your WordPress vulnerability is going to be. And again, this is not an exhaustive direct list right I put it in some type of sequential order, how well depending on your situation and and everybody's perspective, your or your list of priority may differ. But the reason why I'm adding plugins as one of the number one ways, how people like a kid in the candy store. Right for those of us who got kids or that was a kid I believe everybody here should have been a kid but yeah for those of us who have been a kid at some point in time and we had a time there was a time where we had an overabundance and if we had too much. You wouldn't so we try to pick everything I want that the marshmallows and the gumdrops and the Snickers and the chocolate doodles and everything in the world I want it all. And next you know, we are causing our parents way more dentistry bills than necessary. And that is WordPress. And that's how a lot of us are when it comes to WordPress. If you aren't careful on the type of plugins that you use, especially when you're picking a lot of plugins, you have more opportunities for vulnerabilities because just like other areas and WordPress developers can attack plugins, especially when they're outdated. So be careful on the plugins that you use make sure they're from a credible source make sure they're from a company, a dev team a development team that cares about their code that cares about their software and their team, and we'll put that at the time and effort into the plugin. So that's why I'm starting with plugins because most of us don't use WordPress without plugins and most of us, I would say, use plugins that sometimes we don't even really know too much about we just know what it does until we just add it to our website. So be careful with plugins. That's a huge security factor because it you're adding multiple vulnerability aspects to your website. Similar to plugins you have themes that can be compromised right through a hacks or through some type of breach. It's a very similar concept to plugins the difference between the two and its most simplistic form is you're not going to have multiple themes on your website. Now you'll even if you have a child theme, which is a sub theme of a main theme, even when you have that happen, you're not going to have a whole bunch of other activated themes you may have a backup theme on your website which is a good practice to have but you're not going to have multiple active themes where you'll have multiple active plugins. However, just like when it comes to plugins, you definitely want to make sure you definitely want to make sure that you are using a plugin that is credible. Okay, it is credible. And this is important. This is an example of the reason why I'm saying this if you go to the WordPress repo or the theme repo, and you go to popular themes you'll be able to see the most popular themes. I'm sure there's a lot of people here that have their favorite theme so whatever if you have a theme that you feel like is the go to theme is your top dog top notch theme, put it in the chat. Please share that thing that you just love you think is a really good thing. What are my favorite things is this name called cadence. I'm a big fan of that. I also use astra. It's a really good theme as well, and they're backed by a really good company so I really feel secure when it comes to my website because I'm working with a theme that is backed by a team that actually cares. Again, I'm not saying that things can't be penetrated they can't be compromised or they can't be hacked into but you have chances of that less likely happening if you are using with a team that knows what they're doing and that stays on top of things. Like cherry on top of the cake. Now here's an example of a theme being attacked. This is a while ago in January and it was access press, and it was over 90 WordPress themes and plugins and this is not the first time this has happened this was just a big deal at that time, but they were hacked, and it's one of those things where you got to let your users know you got to let people know, you got to let them know why you have to then go into precautions of how to prevent it then you have to earn your trust back from the users, etc, etc. The people that were attacked or had been compromised do they have to make it compensated just what what happens when all those situations happen. So that's why it's something that you want to really think about I don't think people think about that enough when it comes to the website, the importance of having their theme just as much as their plugins, maintained from a credible source. If you have any questions, feel free to put them in the chat but we'll definitely get to everything as much as possible at the end let's see and if you haven't used WordPress I'm going to assume most people in here have used WordPress so this isn't going to show too much but just in case if you go to the plugins you can see here in the plugins repository that you can literally just go here and add or click the word popular, and then you can see the most popular plugins. Now don't let things fool you because this is what's crazy and I know somebody here in this session and speak your mind speak your peace if that's how you feel, but Yoast is one of those ones where it's so popular. They have a cold following, but they did get in trouble they did get a hacked or they had a vulnerability issue and they didn't tell their users for a very long time and they lost a lot of trust when that happened. They're very popular plugin you can see five million activation strong and their SEO plugin. So it's just one of those things where you have to pay attention, you got to pay attention or you have to work with people that are paying attention, because if you're a busy business owner or freelancer blogger content creator, and you're not paying attention or working with somebody who's paying attention. You may have something like Leo's happened and you're finding out an email months later that your website can potentially be compromised from a major company. It happens. Alright, so updates is the next thing that I want to talk about when it comes to your plugins WordPress has different versions and one of the latest major versions of WordPress, not anytime like recent in the last few months but I think it was about a year ago. I had a major update when it came to enabling auto updates. And that was huge because a lot of people were enabling auto updates from other plugins or other hosting functionalities, but now you can do it directly inside of WordPress. And this is one of those things as well that you want to be careful with. Not all updates are created equally. Not all auto updates are created equally. What do I mean by that. You can have an auto update turned on and it updates your website from a major update from a plugin that didn't test out all the bugs in the plugin before they had this major update. So now while you're at home or you're at work or you're out exercising or you're having some fun having dinner or something like that and then you get home and then you notice that your website is broken you get that phone call you get that message that websites broke. How did it break what happened did I get hacked today, but no not really update your website and the bugs weren't fixed yet in the plugin auto updated. So it happens it's not often but it does happen and that's why I'm giving you this little tip right here not saying I don't want you to auto update your plugins. I do it's a best practice but just be aware and understand that it can also do some damage if you're not paying attention. But if you don't update your plugins once again, you are susceptible for being vulnerable to hacking and then this is just another image right here of what it looks like.  If you have your auto updates on you're going to see this little message here that says auto automatic update scheduled in X amount of hours. Yeah, auto updates is one of those tricky things where you definitely want to have it you want to be able to utilize it to have it. The more plugins you have you especially want to have it but then the more plugins you have and the more. I don't want to say lazy but if you're not paying attention to things and just saying the update patterns like seeing okay when you're using these plugins. And you've had auto updates on for a week a month six months have you had any issues yeah if you've had any issues turn that sucker off turn that joint all the way off. If not okay leave it on you just got to be mindful just got to be mindful where press websites are upkeep let me try to check out. If there's anything just I'm just checking the chat real quick. It works well with other plugins not cause it's yeah it's true because look yes look I want to change to different stuff but can I do that. Okay yeah thank you yep thank you definitely can you know change to whatever plugin especially the fact that they have the import settings now. Well one of my favorite SEO plugins is called rank math, and it has a migration setting to come from your specifically. Okay. And this is what it looks like when it comes to the updates from the core version of WordPress so I was talking to you about using the updates when it came to the plugins and the theme, but WordPress itself as I just mentioned, it does have core updates so you want to be checking those, you can also turn those to auto updates if you enable the auto updates for your WordPress core updates, those updates are very important. I will say that's because that's the actual core that's WordPress itself has nothing to do with your plugins, it's WordPress yourself so you got to think. When you think about WordPress there's a couple layers to it and I'm going to get to the next one here in a second, but you have WordPress like the core and then you have WordPress the plugins that technology sector right there. And then I'm going to share with you another technology side but again think of WordPress the core, but the platform, then you got to think about the plugins that you connect to the platform. So think about them separately, not as one thing even though they work as one system. Passwords. This should be pretty much common sense I would assume for most of this in here I think most of this, if not all of us in here are pretty, pretty darn intelligent. And I believe most of us if not all of us understand the importance of passwords, but it's just something that needs to be said as well for someone who does just need a quick reminder. I forgot I got to change 2023. I got to update my password I got to change things I'm doing these things and I'll make one of those people I am so you can boomie or excuse me, excuse me. Yeah, because I got to update my password sometimes I use the same password in certain situations, and that's not a good practice to have my passwords are always very hard though but the same time it's like when you have 100 plus different passwords, I would recommend for those of you all who are using a lot of logins to use a password manager, instead of saving the passwords to your browser I know we get into the habit to that. But make sure that you are using a password that has capital letters, lowercase letters numbers and special characters because passwords are one of the easiest ways to get hacked get your website hacked, especially if you're just keeping it very simple. We get even though we know the common factor of it we just get lack of days ago with things as people sometimes and that's normal that's natural. I just wanted to remind you. You want to use strong passwords is a security factor. Now going to that third part of how I'm trying to get you to think about WordPress in a way right when we're compartmentalizing it. I mentioned WordPress core WordPress plugins. Now let's talk about the WordPress hosting and you can say chicken or the egg scenario right which one came first which one's more important first. I wanted to start with WordPress is first intentionally because I just know people get very excited when it comes to those plugins, because they have you create the functionality in the website of your dreams right hosting is a little bit more. Okay, why don't I care about hosting what I need hosting for until you realize your website is really slow in your life. Oh, but hosting, I would say is very important factor you want to use secure hosting. And you want to make sure that your hosting has a firewall or application firewall, good backups, and some type of malware or site scanning. These are some hosting examples here for anybody that has a host that they do love or please put it in the chat. I just wanted to give some examples of some really good hosts that have these factors involved and they are pretty fast. I always advise people do not go cheap on hosting, you will pay for it later. I promise you. I mean, is a good one as well. So here's a another will say want want want moment right or we call boom moment. So go daddy got breached themselves as well and this is no knock on go daddy but I wish I had my knock knock sound but at the same time, I'm not a fan of go daddy because they just they try to do too much they just try to do too much. They got hacked. This was recent. This was not like a long time ago. And again, they pulled the situation where they failed to let people know they are they took too long for whatever reason it is what it is. But a lot of people sites were compromised because of this and I always advise people not to go go daddy for hosting anyway if you want to buy your domains they are fine, but you don't want to buy land or hosting or trip to the moon will go daddy because you that's a no daddy you don't want to know what you don't get with them. But it happens, even with hosting so hosting is one of those huge aspects of your WordPress website, because there's so many technologies involved with there's so many complexities involved with it that you don't need to know about. You just need to know it's working and working well on your behalf. So again, pick your hosting wisely, not go with cheap hosting or because they doing some gran also deal. When you look at their reputation. It's a little if it's a little if you're on the sideline. So with this really good secure web hosting, we want to think about, as I mentioned, our firewall, you want to think about backups and scanning I use site ground as an example for hosting but whatever hosting you use most hosts have very similar features even if they have a kind of a different back end user interface, like some hosting are still using cPanel right to type of use the interface for hosting, and some hostings are using their own interface so for instance when you use site ground you're going to see something different than you would see when people are using cPanel. So I'm back here in site ground as you can see in my hosting and if I go to security. You can see here that I have backups on the hosting side and that's not the same thing as backups on your website side so this is backups on what they call the server side backups where my server my hosting is backing the site up. But if my hosting goes down. I don't have access to those backups. So you got to keep that in mind hosting goes down. I don't have access to those backups. So backups is a great security measure. It has a firewall as well. I don't think I can get to it from back here but I know in particular that it has a web application firewall. The I haven't gotten to that part yet but I was going to get to it site scanner it has a site scanner here for them they make you for that they do a free site scan. And then for premium they have that you know what type of hosting you use it just depends but as long as you get your site scan for malware so you at least know what's happening. That's pretty much very important, at least fundamentally when it comes to most hosts. So like I mentioned backups on the server side. Now let's talk about backups. All the website side. So if I type in backups back here and WordPress, you choose your backup preference pick your poison people, whatever you feel comfortable with right, but just make sure that you have double the trouble double the fun. It's all great with double meant gum. Make sure you have backups, because if you have double backups backup on the server side backup on the website side if the server goes down your hosting goes down. You still have a backup backing up to let's say Google Drive or Dropbox or Amazon and vice versa say your Amazon goes down to your Google Drive or your Dropbox goes down for whatever reason or there's a malfunction or just an error in the backup. You're hosting to revert back to if something goes wrong. That is one of the best game plans you're going to have when it comes to being attacked, especially when it cannot be fixed when the problem can't be fixed. Or you just don't have the resources to afford to fix the problem so it can be fixed, but you can afford to fix it and just go back to a certain point in time. So do daily backups at minimum 12 hours. If you have certain type of websites that are changing constantly you may want to do hour by hour, or every four hours, but backing up on your server and backing up on the website itself. I'm trying to tell y'all, it saves your life. I just had it happen to me twice when I updated a plugin too fast. And we ended up having to revert to a backup because we couldn't change the website from there. It was a situation where it just couldn't be fixed. So we had to go back to a backup which luckily we didn't make too many changes before that backup happened that latest backup. So it wasn't a big deal, make a couple of adjustments but if it wasn't for that backup in place. Yeah, I would have been messed up. And I'm talking about this just happened last week. I know this is really, it gets real loud here. A secure website address.  And depending on your situation. Okay, this is going to be different for everybody. Right. So I'm just going to give you these different angles here. But depending on your situation. You can get an SSL and you're hosting your hosting can do it for free. Usually they use what's called lesson let's encrypt. Or you can use a plugin on the website itself. So you can do it with the hosting server side or you can do it with the plugin. You choose which direction that you want to go. Just make sure you have that sucker in place. Okay, have that SSL in place. You want to have that lock on your URL you will have that lock here in the browser. That means your website is secure. That is a huge protection factor. So make sure that you have that SSL. Okay, it's for free. And it can auto update and renew. I think it's every three months that it renews. It's just one of those things where you just set it and forget it. You don't have to worry about it no more. You don't even need to know the nerdness behind why it's working or how it's working where it came from where it's going in 2000 years from now. Just know you can set it up and let it go with the wind. This is a classic movie by the way. Now, using a security plugin. This is something that I think that we typically already for the most part know about, but here's some things I want you to think about when using your security using a security plugin. And this is where things get a little sticky because there are so many variables when it comes to different security protocols and factors settings and things you can set up to make your website even more secure literally like dozens of dozens if not hundreds. Man, if y'all are lucky that I don't have my sounds for the people who've been here a couple of times because my roadcaster my audio unit reset itself. And I used to have all these sounds just these clips ready to go ready to drop and they were just pretty funny I used to crack people up, but my anybody got time for that, like I missed that lady because I would just hit it now. We ain't got time for that we don't have time to be doing all of this security stuff and know that's why I'm like let me just give y'all the nuts in the bolts. You can do the rest of your research and move on with your day. But these things are the most important things right here when it comes to your security plugin so login limits, you want to think about login limits. I'm going to share with you show what you what that means like basically limiting the amount of times a person can log in disabling file editing. I'm going to go back to your authentication brute force site scans for some security plugins have sites kids and then some security plugins have firewalls and some don't. So all security plugins aren't created equal and that's why I'm saying I want you to think about what I'm about to show you, because it's something that it took me a while to understand and figure out and I think that it can give you a head start impact your security strategy which direction you want to go. So for instance, if we go back here and I go back to the install plugins, I did a little bit of preliminary y'all did a little preliminary. Meaning like I put the plugins on so that's why they already here, but this is a practice that I would never advise somebody to do you don't want to put forward with security plugins on your website that ain't something that you want to do you only need one starts with one shout out to Lincoln Park I think security site ground security and word friend security are the ones that we're going to look at today as examples of not all security plugins are created equally, but these are some very good and popular security plugins. Okay, give these plugins. So, depending on what security plugin you want to go with and the direction you want to go your settings are going to vary but I wanted to share with you. There are some differences between these plugins. The plugin security plugin that I use currently and it's mainly because I already use their hosting is site ground security so I'm going to activate this first, and then give you a little small tour behind it.  So, in site ground security we have two kind of main menus here. I'm going to talk about we have your site security and then your login security. This plugin is very simple. It's lightweight. It's simple. It gets to the point when it comes to security practices, as I mentioned in our. I'll go back here to our slide that limits login attempts. So, we have that down. Oh, no, sorry, that's in the login one. So while I'm here though. I'm going to go with disabled file editing. So, themes and plugins editor. This is what disabled file editing is going to be here using this security plugin. The limit login attempt is going to be in the login security settings right here at the bottom limit login attempts so again you're just limiting the amount of times a person gets to try to log into the website. Because if they're logging in past a certain amount of times that can indicate that this is not a normal user so you just want to be about that. Here we are we have two factor authentication as well to which is right here. And you can toggle this on and then go through the process of enabling two factor authentication like I said this plugin is pretty, pretty simple when it comes to this plugin and particularly it does not have firewall, and it does not have a site scanning. Now why is that the main reason why is because site ground security plugin is backed by a hosting company site ground and they already have firewall and the site scanning on their hosting side. So hey we're not going to give a free plugin these features to when we have it we're hosting. So keep that in mind that's one thing that if you do have hosting that has firewall and scanning already. This may work for you in your situation even though it's not with site ground right to different hosting company. It still can apply because you can use this with any hosting at all any hosting that you would like just make sure you're hosting that's firewall and security. So I hope that makes sense but I just wanted to give you some insight on that part other than that these other like things that will apply the log and post hack actions meaning what happens after the website gets hacked is very important. Most security plugins though other ones I'm going to show you have these settings as well too. So I'm going to deactivate that one and go to items next, just so you can see the common denominators because I think people get really tripped up with security plugins. I think this is one of my favorite ones it's one that I use with my clients and I also use this when I'm not using like a site ground website I use I think so that's really good. I'm a big fan of not just the functionality of a plugin or an app, which is very important and priority. But how does it, how does it not a person likes to go off of feelings. Okay, but how does it make me feel in a way of motivated to actually be using it inside some plugins are boring right so I'm a big fan of going for either will say profit over preference, if that makes sense when it comes to business sustainability and going with what is the data tell me what are the stats tell me where the facts tell me what is the information telling me and then let me make a logical decision from there. So that's why I'm saying like don't let the aesthetics make have you make your choice of why you use a certain security plugin but when you have the best of both worlds, it feels like a win win right you got the functions features and then you have the aesthetics that look clean look polished, let's say polished, or polished, however you want to say it tomato tomato but when it comes to features and I think security. We have enforcing an SSL, which is not on the list here, but it's something that we just mentioned before when it came to the SSL, adding that to your website so enforcing that with a security plugin is just extra measures right there. So something to that's very important doesn't come with the site ground security plugin which is brute force that is is huge so we have brute force here that doesn't come with the site ground security. Okay, I got to give and I got to take when it comes to my security plugins when when I have to think about the pros and the cons. But we do have site scan scheduling so this security plugin has site scanning so site grounds plugin didn't have that I think does. I think about they both have two factor authentication, and then there's other security factors as well including notifications and configurations but that's the gist. And this does a lot of the job folks I'm trying to tell you you don't have to do much if you have really good hosting, you have a very credible security plugin, you just got to realize what features are coming from your plugin, what features are coming from your hosting. I'm going to deactivate this. Let's go with security and then we're going to go at work fence and then we're going to close we're going to get ready to close it out and do some Q&A. So security now this is something that I had to learn because I'm not going to I'm not going to portray like I'm some security expert because I'm not I know enough security practices I manage a lot of websites, but I am not a WordPress developer there's only so much I'm going to know right when it comes to security I'm pretty much like a lot of people in here when it comes to just security I just want to get in and get out. But I want my stuff secure and I just learned when it came to these different security plugins that yeah there is some main differences between between them and having that or with that being said, you really pay attention and think, do you want an extra layer of something that you may or may not be getting from your hosting. The one example is firewall so I haven't talked about firewall yet when it came to site ground security. I haven't talked about application firewall web application firewall when it came to items, you can see security has one and they're big on that they want you to connect to their system so they can give you some more protection. So you do that with an API key. I believe it's free as far as I know, but once you get your API key. I'm sure you sign up for one for free with your email you added in here. Now you have fire a firewall, helping secure your website as well give you a really huge extra layer of protection when it comes to malware infections and reinfections. And like I said, you don't get that with site ground you don't get that with items, items pro may give you that, but it may not. And when it comes to the security. It doesn't they don't give you a lot of settings like items gives you and site ground gives you for the most part but they do give you other security settings that we haven't talked about like heartening. That's one some security settings that they give you post hack we said we talked about that with items and with site ground scanner, like items as well and alerts. So how they communicate with you when something does happen it's that's important as well too. And then let me deactivate this and activate word fence. I think I saw somebody in the chat said that they did use work and I'm not mistaken but I'll double check in here in a second and then you got word fence now word fence I haven't activated. So if you do use word fence, please let me know what your favorite feature of word fence is another reason why didn't I have it activated was because they wanted you to go through signing up for a license so that was interesting. That word fence wants a license, security wants an API, I themes you can just do it for free go through their setup and then site ground for free as well. But with word fence you do get a firewall for free. So, these are just things that you definitely want to think about when it comes to your security plugin because you don't want more than one. And last but not least, when it comes to at least this will say beginner to intermediate security best practices and factors we ain't going too deep on the deep end now, when it comes to advanced security practices. But this is the last thing that I want to let you know that is a huge security practice, if you need it, and using a content delivery network such as cloudflare cloudflare has a web application has firewall as well to firewall rules as well as security features, and it's more than just a content delivery network meaning it does more than just serve your website across the world. Faster than if you weren't using it right, but it also secures your website from threats and attacks from special threats and attacks at your security plugin is not going to do all your hosting isn't going to do. And that's pretty much it. Hopefully everybody got a little bit of value out of this presentation.


Hello everybody and welcome to another hobby cheating video and today we're gonna take a deep dive into wet palettes What are they? Why should you use them? How should you use them? How do you get the most out of them? Hey, let's get into it. The strict techno man sir. That is Vincy V. Let us get to the technique and learn it Vincy V style Wet palettes, so we're gonna talk all about it We're gonna hit everything to do with them, but right up at the top I do want to say like every hobby tool. It's not absolutely essential when you're in this hobby to use a thing I personally find the wet palette Indisposable and it's a major major part of how I work and how I hobby it doesn't have to be the same for you So if you find that after you try this or something it just doesn't work for you Don't feel bad. You're not doing anything wrong Everybody hobbies in their own way. Okay now with that disclaimer out of the way. Let's talk about wet palettes First off, what is this thing? Well a wet palette in simplest form is just some kind of container Within some kind of thing that can hold liquid water for a relatively lengthy amount of time That could be anything from as simple as a folded up paper towel or kitchen roll or a sponge or anything like that within some kind of You know piece of paper over top of it that is roughly porous and allows some form of osmosis through the water Now there are many versions of this thing You can of course start with a simple homemade wet palette That's as easy as a ziploc container and some paper towels You can make it for literally pennies or you can go get a kitchen sponge and put it in there and put some Paper on top. That's also relatively cheap. I mean, maybe we're up to a dollar now And then you just need a little bit of non wax baking paper for the top I if you're gonna use generic paper I tend to prefer something like Reynolds non wax baking paper like this sort of sheets you used for cookies in the oven Those are generally perfect They're non-stick usually but Just don't get the waxy ones or you can use something like what I use which is the The exemplar from game envy it is my favorite wet palette I have gone through most major every major brands wet palettes And this is the one I've come to that I really love for reasons we'll sort of talk about There are also traditional art wet palettes like the Masterson West wet palette. Those are all fine But I do have some issues with them and we'll talk about it as we move through the rest of the individual features So why is this thing valuable well the wet palettes valuable because there's a bunch of water sitting underneath the paper Your paint is sitting on the paper and through the magical power of osmosis Very small amounts of that liquid come up and slowly hydrate your paint Hopefully and this is the key Hopefully matching sort of the pace of evaporation of water out of your paint And so over the course of a day or a long painting session several hours Your wet palette will keep your paint hydrated and workable so that you can sit there and happily Hobby away painting a miniature for hours without the need to keep wasting paint and having it dry on Traditional dry or well palette What is it not it is not Magic it does not just like you can't put a drop of paint on it And then leave it there overnight with the thing completely sealed And then come back the next day and have that paint be magically perfectly usable or three days later and have that paint be Magically perfectly usable. That's not how this works as soon as you close the top on the wet palette You have reduced the amount of evaporation Significantly There's no light. There's no heat coming down on it. It's a sealed environment It becomes very humid and now your paint, which if it was hydrating properly with the top off is going to hydrate really fast Especially if you have hydrophilic paints, which most acrylic paints are quite hydrophilic It will then become a sort of watery mess if you just let it sit there We'll talk about how you can tackle this later on. Okay, first things first We've got to set up our wet palette. So over on the desk. Here's what we're doing We're gonna set up this wet palette now the first thing to talk about here is the sponges now I particularly love this particular sponge from game envy because it uses the sort of nylon Sponging on one side. So these are kind of half and half sponges. This is the newest version of what they have I think it's super cool. This is actually the revolution to me There's a lot of sponges out there that people will put in these wet palettes The traditional artist palette just has this ugly yellow sponge, which is very prone to mold and basically it's the same stuff as a kitchen sponge You can get them made out of things like this where it's nylon or other certain artificial materials Which does reduce the ability of microbes and stuff to find a home in them And let's be clear right up top your number one enemy with a wet palette is mold You are leaving standing water Just sitting out in the open in your house So if you have a human environment or an environment prone to mold of any kind You're gonna have to take really really strong steps to make sure that your palette does not become a moldy gross mess that will make you sick If you live in a relatively dry environment, they probably less of a concern and the wet palette will become infinitely more valuable Now one of the things I often see people do is just set up one sponge One of the neat things though about this process is that you can if you live in a particularly dry environment Double sponge. So this is what I do. My basement is quite dry so I just often have two sponges in there and That means I can fill up more water keep more sort of moisture in those sponges longer So they feed up through the paper more easily. It allows me to have more standing water Up to a higher level in the actual wet palette itself So that's the first thing you can do to adjust to your humidity and Understanding your local humidity is one of the most important parts about using your wet palette is the area You're painting relatively dry is the area you're painting and relatively humid set it accordingly If it's relatively humid a single sponge and low water is going to serve you just fine If it's really dry two sponges lots of water very very effective So find some happy medium in between there speaking of the amount of water This is another thing I often see people go wrong I look at their wet palette and they have the sponge just kind of like it got near water It met water one time on a trip out West. No, no, no, no, no We've got to get that thing Saturated the sponge needs to be completely saturated with water and then you need a good amount of standing water Basically up to an equal to the level of the sponge or right below it You want the sponge and the water level to be, you know, basically right on Okay, that's how much water should be in your wet palette because over the course of your painting session Water will evaporate. It's not just going up through the paper into your paint It's of course also just going to be evaporating from the palette itself up into the air in your room And this is worse if you have very hot painting lights or a lot of light in your area Which we all should protect our eyes So as a result The more water you have in there the less often you have to refill it the more effectively it's going to Rehydrate your paint now as we're talking about standing water. We've got to talk about mold I mentioned it earlier. Let's get into the nitty and the gritty and the gross Mold is a big problem when it comes to wet palates as I said, especially if you're in a humid or mold-prone environment So what can you do? Well, you can do lots of things So there are various liquids you can buy like cleaners that you can put in there. This is what I use This is the antibacterial agent. It prevents. I've never had mold or anything of any kind as long as I've used this stuff I love this stuff. It's really great You can also put copper into your water. You can use copper wire or Companies will sell a little copper Things you can actually set in your palette for it. You can use You can I've seen people use pennies. I don't really support it There's not that much copper actually on pennies anymore pennies are mostly made of zinc with just like a thin copper coating around the outside So I don't know how much that's actually doing. I haven't seen any kind of scientific test We probably need to get goober town on this one to do this test But a decent amount of copper in the water will actually act as an antimicrobial agent But using something like a drop of dish soap in there can also be a great Play especially if your dish soap is like antibacterial dish soap That's what you would want anything that says like kills 99 million percent of germs great perfect Okay, just a single small drop of that on the base under the sponge before you fill it up We'll do a good job Okay, so now that we've got the palette all filled up and ready to go It's time to talk about paper Now two important things when it comes to paper one in general You don't want to use anything that says wax paper on it in general as always. These are all guidelines So as I said things like baking paper that you would use for making cookies or something like that in the oven Is really your ideal thing you can cut it to size You can also buy those prefabricated sheets and some of them are almost the right size depending on your web Pallet you make especially if you use a homemade ziploc palette. So that's actually just super convenient The Use of wax paper if you live in a very humid environment That can actually be a good sort of trick There will still be some amount of osmosis and humidity traveling even through the wax paper It's not completely waterproof. Obviously. It's just mostly waterproof Um, so I have seen some artists who are in like particularly dry environments or sorry particularly human environments. I apologize Use wax paper to good effect. So again, it's about setting it to your local climate to get the best effects An important note about the paper. It needs to be smaller than the sponge This is actually one of my biggest complaints with a lot of the paper you get In the sort of hobby Space for wet palettes is that many of them are bigger Than the sponge itself. This is no good And it has to be a little bit significantly smaller because as it gets wet It will actually spread out some and look and become bigger as the as the like as the paper Loosens a little bit when it when it gets wet it will grow larger And so you need to be significantly shorter than paper when it's dry that way as it spreads out you're not Dropping over the edge. This is important because if the paper's hanging out over the sponge Then it's just you're you're you're just going to evaporate a ton more water Your paint will get dry much faster and the wet palette won't really work The paper needs to be smaller than the sponge so important so vital so many people miss it Okay, now that we've got our wet palette all set up. Let's get some paint on here The first thing I'll say is just because it's going to keep your paint working doesn't mean you need to go crazy In fact, you can do the opposite now you use you waste much less paint with a wet palette Because you're only putting a few small drops of paint on that paint is going to stay workable for hours and hours and allow you To get a lot more out of a lot less So if you're one who's thrifty like me a good wet palette can actually help you save money because you don't waste paint As it just dries and dries and dries over again Over and over again on your plastic well palette Once we have all our little drops of paint that we're going to use on the palette set up We're then going to slowly and this is my particular method You might find a different method of working But I then like to work out from those individual little pools of paint So I never actually mix in the original pool. I take a drop of the paint I put it somewhere else on the palette and then I Uh go to the next color or make my mix or thin it appropriately whatever I'm going to do So I'm working always from secondary pools of paint The original little drops of paint that I put on the wet palette Always stay clean stay original and allow me to always go back to a nice Uh original base color or tone or whatever and and that remains then workable as I make different mixes Or something like that without polluting the other colors This also is sort of the way my brain just works Yours might be a little different, but working from a secondary Pool is if you're needing to mix or thin is a very important step If you're just using the color straight, you don't need to worry about the the second pool of paint speaking of thinning Isn't that kind of the point here? Yeah a little so this is something I often hear people say Is it by using it on the wet palette? It's already thinning the paint. Well again Yes, sort of but it's not magic Right, so this is a slow process of the osmosis absorbing some liquid up into the paint If you put a few drops of paint onto the palette and then immediately start working with it within the next 60 seconds Guess what it has not thinned at all But it has because it hasn't absorbed any real water yet As you work with it over time Potentially it will become a little more thin Maybe the equivalent of having a moist brush when you go into the paint So this can be a way to Get your paints a little thinner as you're working over time But do note how long the paint has sat on the palette will be impactful to how thin That paint is and as you're working sort of with the Top off and with a lot of light It might not actually be getting that much thinner because if the rate of sort of absorption through the paper is Equaling the rate of evaporation you're probably going to stay about the same now once you've got those paints somewhere else Thin mixed etc Then we can do the roll the dab and roll or the roll and dab I guess it'd be the roll and dab But this is a good way to just sort of keep your brush working and sharp Once i've worked the paint and i've got it where I want I then i'm going to roll my brush off and on the palette wiping away the excess And then if i'm working with a very liquidy paint say a glaze or anything very thin an ink something like that I'm then going to dab a piece of cloth or paper towel that sits next to my wet palette to get that excess liquid out of there This is especially important if you're you're in a situation where your wet palette has highly hydrated your paint Then you want to be dabbing often Uh just to make sure that you get all of that paint You know off or sorry all that excess liquid out of your brush Dab dab dab Now I want to end on just some general tips These are just bonus tips that I found for years of working with my wet palette First off don't seal the thing completely at night Some palettes like the exemplar have a little vent you can actually open at the top That will do some work to still allow some air exchange and prevent the environment inside from becoming too humid You can also just not seal the top you can leave it slightly to the side or something like that Though I suppose that can be problematic if you have cats or other animals that want to climb up on things and knock stuff around So you know buyer beware on that one But leaving it uh the lid adjacent ajar open slightly will also help the the environment not become too humid and over liquidate your paints Uh in that case depending on what your local humidity is you may actually find you can come back the next day and Still find your paints completely workable and ready to go and you might get more than a day out of them Which is which has actually been really great Next up wash your wet palette regularly doesn't have to be every day But you know once a week take that wet palette dump the water throw away the paper Whatever you're doing take it upstairs get your brush that you use to clean your dishes Get some dish soap give that thing a good scrubby scrub rinse out the sponges Put it all back together refill the water take it back down. It's just a good process Again, not only does it help to keep you know mold and other things like that out of there But it also just helps it not be sort of gunky and gross paint sometimes will leak in the side of it You know dust from your room gets in there.   Just some good cleaning once a week should keep you in proper working order with no issues as you're working with the Wet palette you do want to make sure you refill your water regularly I actually keep a little squeeze bottle, which I also wash once a week Next to my area that I can just sort of squeaky squeaky squeeze Into the wet palette and refill the water back up to that level to keep it nice and even with the actual sponge So make sure i'm getting that appropriate level of hydration Up through the paint finally and this is a particularly fun one if your paint does become over hydrated It doesn't mean you have to throw away the piece of paper or anything like that what I usually actually do because Overnight oftentimes to some of the paints that I use are really really hydrophilic And so they will become over liquidated over hydrated. Whatever you want to say they become just watery piles of paint You can though handle that. I take a paper towel I simply press it down on top of the paint I press it down on top of that and it simply soaks up All of that excess liquid and water and admittedly some of the paint Now usually what you'll have left is not usable sometimes it is But it will absorb all that water And then you can keep using the palette without worrying about that very wet paint running everywhere or getting into anything You can keep using all the space around it without issue. So there we go That brings us Through everything you need to know to be rocking and rolling with your wet palette Like I said this the one that I'm using and that you've seen in this video is the exemplar from game enby I really do love this wet palette. I love the sponge design. The paper is really great Everything about it's you know durable. I've never had any mold issues. So to me this one's a winner But you can find whatever works for you And that's perfectly fine I will drop a link down below to the exemplar. They didn't sponsor this video. I don't have any relationship with them I just really like the product. So there you go If you liked this give it a like Subscribe for additional hobby cheating in the future. Don't forget. We have new videos here every Saturday If you've got any questions about the wet palette or anything I didn't answer drop that down in the comments below I'm always happy to answer every question asked If you want to support the channel, there's lots of ways you can do so share this video That's number one number two. You can check out the merch store down there. We've got lots of fun merch Number three. You want to directly support the channel? Well, there's a patreon focused on review and feedback And taking your next step on your hobby journey. We'd love to have you as part of the community As always though, I thank you so much for watching this one and we'll see you next time


ణార్టి రియానోయతోమ్ఒచేనితాడి కెన్రందాటాంచి. క్రర్మోఖేగితోదా. విలాపనాసి బరర్వసి నీంకుకాయారోాసి ఇలార్నోటి . .Also, we developed an expression for specific speed of Francis runner mainly in terms of the angles of the guide vents at the exit and the angle inlet angle of the runner blade. The usual values or the typical values that cover the actual case for a Francis turbine are like that. The alpha 1, which we already noted that it is the outlet angle of the guide blades usually varies from 10 degree to 40 degree. We must know these values in practice. The beta 1 that is the inlet blade angle which varies from 45 degree to 120 degree with respect to a typical blade of a Francis runner. So, this is beta 1. So, this angle is beta 1. Well, the ratio of width to diameter at the inlet b by d which is very important in determining the flow velocity v f, determining the flow velocity v f which remains constant throughout the flow through the runner blades which varies from a value of 120 to two-third. These are the typical ranges between which the pertinent geometrical dimensions are kept and the combinations of these covers a wide range of specific speed n s for the turbines from 40 to 500. Very wide range of specific speeds covered by a Francis turbine radial flow reaction turbines. Now, as the specific speed increases mainly beyond 500, what happens is that the head under which the runner is working is getting reduced. So, therefore, essential feature of a turbo machine at a higher specific speed that means that a lower head is that it should admit a relatively large amount of flow to get some definite work output. So, therefore, the runner should be capable of handling or allowing a more amount of flow to get a very definite work output when it is operating at a very lower head at a higher specific speed. And this for to meet this requirement the shape of the runner blades have to be changed and the type of the runner also changes. For a maximum flow through the runner the flow velocity has to be axial that means if the flow rate through the runner blade has to be made very high the flow velocity has to be axial that means the direction of the flow velocity should be parallel to the direction of the parallel to the axis of rotation. And to do this and to accommodate the flow and to extract the work from the fluid flowing through the runner the shape of the runner blades have to be changed. So, this is accomplished in a machine known as axial flow turbine axial flow turbine and a machine of this type axial flow turbine was first turbine sorry axial flow turbine was first developed by an Austrian engineer Victor Kaplan and that is why the name of this turbine is Kaplan turbine according to the name of the scientist Kaplan turbine. So, Kaplan turbine is specifically an axial flow reaction turbine which is used for a very high specific speed range beyond this 500 at max higher efficiency. So, let us look what looks like a typical axial flow turbine or the Kaplan turbine which is sometimes known as a propeller a propeller or Kaplan turbine you see these are the guide vanes. So, fluid while after passing through the guide vanes the pipe vanes are such the ducts are such it is bent right angles in axial direction. So, it first enters to the guide vanes almost in a radial direction as it happens also in case of a Francis turbine then it is turned to right angle to the axial direction. So, these are the rotor blades or the runner of the turbine. So, this is the shaft usually those machines have vertical shaft. So, if we look a plan view. So, the runner blade looks like this the numbers of runner blades are usually small. So, here what happens the fluid flows parallel to the axis of rotation throughout the runner which means the entry is axial the exit is also axial. Now, I have mentioned earlier also the purpose of the guide vanes is to direct the fluid accordingly to the runner blades and also to input a little amount of pre-wheel that means a tangential component of velocity to the fluid. Now, the tangential velocity in the fluid approaching the runner is such that it can be approximated by a free vortex motion why if we neglect the friction in this duct then we can say that in absence of friction and when no work is done or extracted from the fluid then the tangential velocity there is any follows a free vortex type of motion which means the tangential velocity decreases with the increase in radius, but what happens to the blade velocities the blade velocities increases with the increase in radius because it is a solid body rotation. So, to take care of this different relationship between the fluid velocity and the blade velocities typically the tangential velocities the tangential velocity of the fluid approaching the blade and the blade velocity linear blade velocity blades are made twisted twisted means the blade angles from inlet that means the root not inlet I will tell root to the tip is varying this is known as twisted blades these blade are made twisted twisted blades twisted blades blades, the blades are made twisted. So, the flow takes place axially, almost axial through the blade, a typical peripheral section of the blade is like this. Now, if you draw the velocity triangle here, you see that the velocity triangle is like this usually. The most important feature is that flow velocity, that means this is the rotor speed u, this is the v r 1 and this is the inlet velocity. This is the flow velocity v f, which is axial here. That means in reaction turbine, in radial flow we have seen the inlet, that means either with respect to blade or the absolute velocity was in radial and tangential plane. Then it has both radial component and tangential component. In case of an axial flow turbine, it is other way, it has got tangential component.  The outlet velocity triangle, if you draw, will be the same as that of a radial flow reaction turbine. This v f 2 is equal to v f 1, which is equal to v a, that means the axial velocity of flow. This is typically, this is this direction, this is the u and this is the v r 2. One important thing is that the blade velocity is same at both inlet and outlet. In my diagram also, it does not look like that. Their lengths are not same, because they are same, because they are in the same axial, they are in the same radial location. That means the flow is in axial direction. So, radial location at inlet and radial location and outlet is this same. So, this is the principle feature of a axial flow turbine. The blades are twisted and the flow is throughout the axial. The main feature is that, in this case the flow velocity is much higher as compared to that in the radial flow reaction turbine. The flow velocity is here in the axial direction, because the main flow is in the axial direction. So, this way this turbine is capable of handling a very high flow rate and therefore, it is suitable for a lower head or a higher specific speed at higher specific speed, higher specific speed. The runner runs full, completely filled with the liquid, so that the reaction is imparted on the liquid and moreover the degree of reaction in this type of machine is higher than that in case of a radial flow Francis turbine. Well, after this now I will go to the discussion on draft tube, application of draft tube. Now, I have already told earlier that a draft tube is attached always to the outlet of the runner of a reaction turbine to minimize the energy loss at the outlet. Now, at the outlet end of the runner of a reaction turbine, the kinetic energy which is coming out is loss. So, if the fluid comes with a very high velocity that means, the loss in energy in terms of the kinetic energy of the fluid is very high. So, therefore, what happens is that a divergent duct is attached to the outlet end of the runner of the reaction turbine, so that the velocity of the fluid is reduced that means, a decelerating flow is caused in the divergent tube as you know in the fluid flows through a divergent duct as the area of cross section increases in velocity decreases. So, therefore, at the outlet end the velocity of the fluid gets reduced and therefore, the rejection of energy at the extreme outlet of the machine is very less. In another look we can see we can see from another point that we have already discussed earlier as seen that if you write the energy equation of the Bernoulli's equation between the inlet to the draft tube that means, the exit of the runner and the final exit of the draft tube we see that since the discharge from the draft tube is at atmospheric pressure and more over the flow through the draft tube is a decelerating flow that means, velocity is decreased. So, therefore, the pressure at the upstream part that means, for example, at the inlet of the draft tube is will lower than the atmospheric pressure because pressure has to increase for decelerating the flow which means in other way the outlet end of the runner is running at a lower is running with a lower or a suction pressure in comparison to that of a runner without a draft tube. So, therefore, the effective head across the runner is increased by attaching the draft tube this can be looked from this angle also that draft tube reduces the pressure at the runner outlet. So, this is the precise principle of a draft tube how it increase the head across the runner. Now, therefore, we see that the purpose of the draft tube is to reduce the energy at the outlet and thus to increase the head across the runner. Now, two things have to be kept in mind while designing the draft tube. Now, you see draft tube is a divergent duct first thing is that when we extract more energy in the draft tube that means, how do you extract energy that means, we reduce the loss at the outlet or we reduce the pressure at the outlet end of the runner to do that we will have to keep in mind that the loss of energy while flowing through the loss of energy of the liquid while flowing to the draft tube should be as small as possible. So, what are the sources of error one source of error is the usual friction loss that is the friction between the fluid and the solid wall or between the fluid to fluid another source of error comes while a fluid flows through a divergent duct is the loss due to boundary layer separation do you know what is that the loss due to boundary layer separation do you know it well. Now, what happens when the fluid flows through a duct of uniform cross sectional area or fluid flows through a duct of converging cross sectional area that means, either fluid flows in uniform velocity or fluid flows with increasing velocity in accelerating flow loss which is incurred is only due to friction that means, between fluid to fluid that is fluid viscosity and fluid to solid friction, but when the fluid flows through a divergent duct then another additional loss comes loss in head the loss in total energy is known as boundary layer separation what happens is that when the fluid flows through a divergent duct you see the flow is a decelerating type that means, according to continuity when the cross sectional area increases the flow velocity decreases in compliance with the Bernoulli's equation the pressure increases when the velocity decreases the pressure increases that means fluid flows against an adverse pressure gradient that means fluid flows from a lower pressure to a higher pressure. So, why the fluid flows yes the fluid does not flow from a higher pressure to lower pressure that is not the nature's law nature's law is that fluid flows from higher energy to lower energy. So, fluid is capable of flowing from a lower pressure to higher pressure because its energy at the lower pressure condition that means that the upstream condition is more than the downstream condition then only the fluid is capable to overcome this adverse pressure gradient, but what happens what the fluid which is very near to the solid wall as you know the influence of solid to the fluid gives rise to the formation of a boundary layer or what happens is that due to the frictional interaction between the solid and the fluid it is the consequence of the fluid viscosity that the fluid particles near the wall loses its velocity and in fact at the solid wall fluid velocity is zero if the solid surface is at rest that means no solid condition you know from your basic knowledge in fluid mechanics that the relative velocity between this fluid particle and the solid surface at the wall at the solid surface is zero. So, therefore, for a static solid surface static that so fluid velocity at the wall is zero. So, therefore, very near to the wall adjacent to the wall fluid velocities are very small. So, the small velocity fluid particles do not have sufficient kinetic energy to make their total energy compatible for flowing from upstream to downstream section. So, therefore, they become unable to surmount the adverse pressure instead what they do they follow the favorable pressure gradient that means they follow the path from a higher pressure to lower pressure. That means in a direction opposite to the direction of the bulk flow which is away from the solid wall. So, therefore, you will see that the fluid particles near the wall goes on flowing in opposite direction a flow reversal takes place. So, this localized flow reversal makes a recirculatory flow and forms in terms of fluid eddies and this fluid eddies a recirculatory loop along with the main bulk flow causes a loss of energy. This loss of energy mechanism is like that a pressure energy a part of mechanical energy is converted into intermolecular energy which we call as a loss of energy from the few point of mechanical energy. As you know when you deal with the mechanical energy you have already heard this term loss of energy in Bernoulli's equation energy can never be lost from the conservation of energy principle which means a part of mechanical energy which is converted to other form of energy which is not the mechanical energy we call it as a loss of energy. That means this is a loss of mechanical energy due to friction because of the formation of eddies due to a recirculatory reverse flow at the solid wall why the fluid particles cannot surmount the adverse pressure in because of their low velocity. This is a very important phenomena of separation wherever you come across flow through divergent duct or desolarating flow this type of phenomena comes known as boundary layer separation. To avoid this or to keep this to a minimum value the most important factor is that the angle of divergence or rather the rate of diffusion that is change in pressure or the change in velocity has to be made very low. Usual recommendation is that the angle should be within 8 degrees 8 to 10 degrees to avoid the boundary layer separation as much as possible. So, therefore, we see that in designing a any divergent duct in any application it is not always for a fluid machines that there are two criteria comes into picture one is the loss due to boundary layer separation loss due to boundary layer separation loss due to boundary layer separation loss due to boundary layer separation loss due to boundary layer separation another d another is friction loss frictional loss frictional loss and one thing you must know at this level that these two losses are the consequence of viscosity if the fluid is ideal neither of these losses will take place. So, you must clear your basic concept in fluid mechanics along with the additional information in fluid machine that losses due to boundary layer separation and friction loss takes place because of the fluid viscosity why because the phenomena may occur, but the boundary layer separation will not take place even if there is an adverse pressure in because the fluid particle having a low velocity at wall depends upon the interaction between the fluid and the solid surface through the viscosity of the fluid. So, these are contributed by the viscosity of the fluid. Now, the basic intention of designing any draft tube is to keep this loss to losses to a minimum value. So, that the energy is not lost where we want to retain the energy in the form of mechanical energy. Similar will be the considerations for using or providing draft tubes in a reaction turbine. Well, let us see what are the different types of reaction turbines usually incorporated in practice. Number one is straight type you can read it this is straight type this is a simple conical the frustrum of a cone a simple divergent duct straight divergent duct the angle included angle is limited to 8 degree the same angle is 4 degree this type of conical draft tube this is a vertical one it is directly attached to the outlet end of the runner it is very efficient and its efficiency lies between almost equal to 80 percent in this connection I must tell what is efficiency the efficiency you can define of a draft tube or any divergent duct in transforming the pressure energy to velocity energy rather velocity energy to pressure energy like this the inlet head inlet head that means total energy at inlet per unit weight minus head lost in the flow divided by the inlet head for an ideal fluid this efficiency is 100 percent that means it is an index of the head loss the efficiency is high means the loss of head by this two mechanisms will be low. So, therefore, this type of machine gives almost 80 percent 80 or I feel 80 to 90 percent efficiency and these are used for small specific speed low relatively low n s t specific speed turbines with vertical shaft now another type of draft tube these two types are elbow types now these elbow types draft tubes are used where sometimes in certain places sometimes we see that to reduce the cost of excavation particularly in rocks we use this elbow type draft tube where if we go for a vertical draft tube from a from the place where the runner is installed at a height from the tail raise level we see that we have to go for excavation in rock. So, to keep the cost of excavation minimum the draft tube is bent in the horizontal direction to keep its length it is very very it can be seen very clearly in this figure. So, it is this is known as elbow type that is from vertical to horizontal because of the shaft change in the direction of the flow the efficiency of this type of draft tube is in the order of 60 percent. Sometimes the cross sectional area is changed from a circular at the inlet to a rectangular rectangular at the outlet to minimize the frictional losses. So, that the efficiency is little higher. So, in practice several types of draft tubes are used. So, you see the angle of the draft tube is limited that is diverges angle by the flow separation loss and the length of the draft tube is being compromised within the friction between the frictional loss in the draft tube and providing the length suitably either in the vertical direction or horizontal direction depending upon the places of application whether to reduce the cost of excavation in rocks we have to place a horizontal part you have to incorporate a horizontal part where the vertical part of the inlet portion has to be bent with horizontal part in sacrificing certain amount of loss by the change in direction. Now, after this I will come to another very important phenomena cavitation in a fluid machines. Now, cavitation this word as applied to the fluid flow is not necessarily restricted to fluid machines or a reaction machines this is applied to any fluid flow problem or to any hydraulic circuit probably you have heard the name cavitation while reading the siphon in your basic fluid mechanics class while you have read the siphon you have seen that the pressure becomes low at some points in the siphon where the problem of cavitation comes what is cavitation now let us define the cavitation in this way that if there is an hydraulic circuit that means the circuit which contains the flow of a liquid and if there is any chance of having pressure lower than the atmospheric pressure at some part or during some region of the flow of that hydraulic circuit. So, one in that case in that case one has to be very careful that this pressure that the minimum pressure which is below the atmospheric pressure should not fall to the vapour pressure below the vapour pressure or equals to the vapour pressure of the liquid at the working temperature why if the minimum pressure in the hydraulic circuit falls to the vapour pressure of the liquid at the working temperature liquid starts boiling at that pressure. So, when liquid starts boiling so pockets of vapour liquid vapour will be formed which will simply lock the flow or stop the flow this is precisely what is known as cavitation what happens there after is that when the vapours are formed where the pressure is sufficiently low they are carried away with the liquid to a high pressure region where the vapour collapses or busts forming into cavities and the liquid from surrounding zone rushed to fill up the cavities and if this phenomena bursting of the vapours takes place very near to the wall and liquid from the surrounding region rushes to fill up the cavities they causes an erosion effect to the wall of the tube or wall of the duct causing damage the damage is found in the form of pores in the wall of the duct or wall of the tube. So, therefore, it is dangerous to allow such phenomena to occur not only the flow will be stopped within few minutes the wall of the duct or the duct itself or the tube itself of the hydraulic circuit that part of the tube will be damage to the own out. So, this phenomena is known as cavitation. So, therefore, we will have to have a check at the minimum pressure section or the point of the hydraulic circuit. So, that the pressure at that point should not should be at least more than the vapour pressure of the liquid corresponding to its existing temperature similar is the case for a draft tube. Now, if you write the Bernoulli's equation as I discussed earlier at the inlet to the draft tube and the outlet from the draft tube. Let us consider the inlet where the pressure is p minimum because we know that in a draft tube this minimum pressure will occur at the inlet to the draft tube that means at the outlet of the runner. Then I can write the equation like that p minimum by rho g let v is the velocity there that means this v is the velocity coming out from the runner outlet or this v is the velocity at the inlet to the draft tube. Let z is the vertical height from a reference datum which is usually taken as the tail raise that means this is the height from the tail raise to the inlet of the draft tube that means this is the height at which the runner is placed. This I can write is equal to p a by rho g because the outlet pressure of the draft tube is the atmospheric pressure draft tube discharges liquid into atmosphere. Now, if we neglect the velocity at the outlet end of the draft tube we can neglect it if we consider the draft tube sectional area is such that its velocity at the outlet is negligibly small compared to its inlet. Then the datum it is zero because we have taken the reference datum at the tail raise level itself then another term is this head loss h f that is the loss in energy due to friction and boundary layer separation or due to the change in direction. So, it consists of all the losses in course of flow through the draft tube. So, here we see that p minimum by rho g is equal to p a by rho g minus v square by 2 g plus z plus h f. So, we see that if the velocity at discharge from the runner or at inlet to the draft tube is very high or the height at which the runner is placed from the tail raise level is very high. There is every chance that the minimum pressure at the suction may fall below the vapour pressure because the minimum pressure will depend upon this quantity more is the velocity at the inlet to the draft tube more is the height of the runner from the tail raise level less is the pressure at the inlet to the draft tube. Of course, the friction makes an advantageous case in advantageous case in this situation for the p minimum, but the frictional loss is very less as compared to the total energy v square by 2 g plus z. The friction puts a short of resistance you can understand physically this way sir why you may ask that friction increases the pressure because friction puts a short of resistance to the flow frictional loss. So, that the upstream pressure is somewhat increased. So, the influence of friction here is favourable as far as the reduction in the p minimum is required. Now, the basic consideration for cavitation not to occur is p minimum should be greater than p v that means, the vapour pressure of the liquid used.  Now, this part is expressed in practice as a function of the head across the runner that function is sigma c. So, let us express this way you can see this then we can write that sigma c becomes equal to becomes equal to p a by rho g minus p minimum by rho g minus z by h this sigma c is known as critical cavitation parameter critical cavitation parameter critical cavitation parameter critical cavitation parameter and it is an operating condition of the turbine which depends upon the minimum pressure at the runner outlet the height at which the runner has to be installed and the head across the machine. Another parameter sigma is defined according to a German scientist Thoma is known as Thoma's cavitation parameter which is used as a design criteria or a design parameter to determine whether the cavitation will occur in a particular situation or not what is this this is simply the same thing almost, but instead of p minimum we substitute the criteria that is the vapour pressure it is the limiting value by h that means in under all situations cavitation to avoid this p minimum has to be more than p v which means sigma has to be greater than sigma c to avoid cavitation well to avoid cavitation. What is done in practice that this sigma is calculated Thoma's cavitation parameter with the vapour pressure of the liquid and under the operating conditions sigma c is calculated and it is checked that whether sigma is greater than sigma c or not. Now you see the head of the runner is increased or the height of the runner from the tail less level is increased sigma is reduced and there is a chance of cavitation to occur. Usually what is done in practice that from this equation the maximum value of z is calculated that means let us write the z max that is the maximum height of the runner that means the maximum height at which the turbine runner can be placed will be sigma rather I can write this way p a by rho g when the p minimum will reach p v p v by rho g minus sigma c into a that means this equation gives z is equal to p a by rho g minus p minimum by rho g minus sigma c h. So, in p minimum will reach p v that is the vapour pressure which will give the maximum z. So, the values of sigma c the operating parameters are known to us in case of design while we design the turbine. So, knowing the value of sigma c we find out what is the maximum z that is required now sometime it appears that when h is very high that means turbine operating under a very very high head that means the low specific speed z max is reduced. Sometimes it appears that z max may be negative that is turbine has to be placed below the tail water level the situation is not so this is because the sigma c here is a function of is a function of specific speed of the turbine. I give you an example that if we plot the values of sigma c which are available to the design engineers in practice with n s t the values are like this for a francis turbine francis for a kaplan turbine it is like this kaplan turbine. Now, it is found for a francis turbine the values of sigma c is a direct function of the specific speed. So, when the head is high specific speed equation n p to the power half by h to the power five by four that means at a higher head the specific speed is low. So, therefore, we do not go for a kaplan turbine rather we go for a francis turbine where we find at a lower specific speed these all specific speed range for the reaction turbines only the lower specific speed the values of sigma c is also low. So, that if we employ the value of sigma c even at a higher head we get a value of z max which may not be negative. So, the difficulties can be avoided that turbine may not be set at a level below the tail less water level, but the height above the tail less water level must be very small not very high to avoid the cavitation well. So, this is about all this is all about the cavitation in a reaction turbine. So, if you have any questions you can ask me. So, today up to this only well please any question this cavitation principle of draft tube and the cavitation it is very important parameter cavitation is a very important parameter in designing any hydraulic circuits where there is a chance of pressure within the circuit to fall below the atmospheric pressure. So, you must know this thing any question ok. Thank you.


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Here we go, the fourth exercise is fox out, which means whisking hand. Get in your position again, and then get into your ready position. Now, what I want you to do is to chop your hand sideways towards the eye level, and then as you bring this in the back into a Wu style, which is protecting hand, whisk the other one out. Don't look that way, just whisk without looking, and keep looking straight. So, if you put it together, it's going to look like this. We're going to whisk to the left and right, just like that.