Avionic packages housed inside Launch Vehicle (LV) compartments are subjected to varying thermal environments. Thermal analysis is carried out to estimate cooling requirements during prelaunch phase and compute package temperatures with the aim to ensure safe temperature levels till end of mission. Conventional lumped mass approach is adopted where the avionic packages are modelled as cuboids. Commercial Computer Aided Engineering (CAE) software packages are used for analysis. However these require considerable lead time for pre-processing.

This paper describes development of an in-house software which can carry out thermal analysis of avionic packages in LV compartments and provide thermal management solutions. The software can generate elements for generic shapes which are commonly encountered in LV compartments. Software capabilities include handling temperature dependent material properties, isotropic and orthotropic materials, time varying power dissipation, radiative heat transfer for two dimensional elements with view factor calculations, thermal coupling between discontinuous elements and time varying heat transfer coefficient.

Software is written in C++ language using object oriented programming techniques (OOP). The user interaction with the software is through text files which enables ease in model preparation, verification and modification. A graphical user interface is also included for visualizing the standard model and computed results. A typical LV equipment bay thermal model was generated and prelaunch phase analysis was carried out. Computed temperatures were in agreement with measured data validating the software and its methodology.