Approach for Sizing and Turndown Analysis of a Variable Geometry Spacecraft Radiator

Over the past few years, NASA has funded the development of several prototype radiator designs which use shape memory alloys to actuate cylindrical panels in response to changes in temperature. By adjusting each panel’s view to space, variable geometry radiators aim to improve the variable heat rejection capabilities of future manned vehicles in a consumable free manner. A system level radiator model can help evaluate developing panel designs, but is difficult to construct due to the large number of panels that compose a radiator, as well as the parasitic heating of the panels. This paper describes a method for modeling a vehicle-sized variable geometry radiator using Thermal Desktop (with SINDA FLUINT). It exploits the Dynamic SINDA feature in combination with custom subroutines to piece together a string of steady-state solutions into a solution for the entire radiator. Only a small portion of the panels need to be physically present in the model. We demonstrate how this approach can be used to determine the size and minimum operational heat load of an example radiator configuration. Predicted radiator sizes are shown to be consistent with hand calculations using known fin efficiencies and sink temperatures.