Application of a Physics-Based Stabilization Criterion to Flight System Thermal Testing

Goddard Space Flight Center, Greenbelt, Maryland

This innovation consists of a procedure and set of equations that allows thermal balance steady-state temperatures to be predicted hours before the balance is reached based on current temperature and rate-of-change measurements. This will allow tests to run faster, since thermal plateau settings may be adjusted prior to reaching an equilibrium state. Additionally, it will allow the test conductors to identify future limit violations hours before they may happen, which would increase flight hardware safety. A similar methodology can be used to predict component temperatures in flight, assuming a relatively constant sink temperature condition, which would be useful for long cool-down missions such as the James Webb Space Telescope (JWST).

Currently, temperature stabilization points are estimated using thermal analysis prior to exposing the hardware to a thermal environment. This has the limitation that predictions include errors that are intrinsic in the analysis. This work attempts to remedy this by introducing a simple procedure to predict thermal stabilization or balance points based on current test conditions and simple parameters about the component (mass and coupling to the sink).

The process described in this report is used to predict the thermal balance conditions that hardware will experience before those conditions are reached using simple parameters, the current temperature, and rate-of-change. The governing equations are derived from the Conservation of Energy equation, and the radiative and conductive heat transfer equations.

This work was done by Matthew Garrison of Goddard Space Flight Center. GSC-16297-1
