Thermal Radiative Simulations and Measurements of a Scramjet Test Rig

Thermal radiation is a poorly understood process in scramjet engines, but it may play a significant role in the flow and wall heating of the combustion chamber. However, current simulation methods for predicting the thermal radiation in a flight scramjet combustion chamber have yet to be validated with experiments. An experimental measurement apparatus is placed at the rear exit of the HIFiRE 2 direct-connect rig at NASA's Langley Research Center. An array of photodetectors gather emission in the infrared along several lines of sight across the combustor exit. The fields of view are simulated using a ray-tracing-method program that postprocesses a computational fluid dynamics flowfield simulation of the test rig. The ray-tracing program employs a simplified two-point correlated-k spectral model with spectral model error bars. The predictions show an overlap in sensor and experimental predictions for 13 of 16 photodetectors.