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Description
It is common for CubeSat missions to use simplified analysis models, leveraging software suites which are tuned for thermal analysis with coarse mechanical and power dissipation models of spacecraft components. The inherent non-linearity of thermal simulations and the complexity of typical boundary conditions for realistic satellite components often result in this trade-off and reduction in the simulations’ fidelity.
Even though it is not specifically tailored for space-domain simulations, ANSYS Icepak provides a much more detailed PCB and component thermal model which can lead to significantly improved fidelity. EnduroSat has developed a strategy for modelling the LEO environment experienced by a satellite by applying determinate fluid settings inside the calculation domain (cabinet) and imposing realistic boundary conditions exported from a proprietary software. This software uses the NRLMISE-00 atmospheric model and accounts for surface optical properties, producing as output the Sun, Earth IR and Albedo fluxes impacting on each exposed surface of the spacecraft.
The benefits of this strategy is the capacity to readily import ECAD files of PCBs, of both subsystems and solar panels, define dissipations on the level of EEE components and obtain very precise thermal map throughout the satellite components.
In the present work, we outline the methodology and compare the numerical results obtained through ANSYS Icepak with those measured from orbit by one of EnduroSat's satellites. It is shown that about 5 orbital periods are sufficient to reach a steady-state temperature trend for all points of interest given the particular mesh settings and satellite properties. The accuracy obtained is better than 5 degrees after fine-tuning of parameters which are not directly measurable.
Apart from fidelity, the ECAD import feature of ANSYS allows for a detailed analysis of specific electronic components, which may require a specific vias pattern to dissipate their waste heat, allowing then for the hardware engineers to have direct feedback on their PCBs thermal design in a much finer detail.
