A Figure of Merit Based Computational Heat Transfer Method for Aerothermal Analysis of Airborne Electronics System LRU

Aerospace technology is evolving at an unprecedented pace. Modern aerospace systems rely heavily on the capability of avionics system for operating various onboard systems such as communication, tracking, targeting propulsion, flight controls, etc. As power of electronics keeps increasing and the size continues to miniaturize the issue of high thermal fluxes becomes increasingly significant to flight vehicle designers. During design phase, this problem is often tackled by employing tedious computational techniques because generalized analytical solutions do not exist for specific airborne electronics scenarios. For this purpose, an alternative (novel) aerothermal assessment method is proposed using a Figure of Merit (FoM) based nominal fidelity empirical technique. The method is designed for the specific case of an electronics LRU placed in an unconditioned bay exposed to varying flight speeds and altitude regimes. The FoM terms are used to create a non-dimensional correlation between aerothermal design parameters and operating (flight) parameters. The aerothermal conjugate heat transfer analysis is then solved for constant speed with altitude variation to assess the effects on heat transfer coefficients as well as enclosure wall temperature. The results of FoM based empirical method show that the thermal analysis exhibit results that conform to the distinctive behavior in troposphere and stratosphere regimes. Moreover, the FoM based thermal analysis results appear to be in good conformance with high-fidelity CFD solutions.