New gauge design to measure radiative heat transfer to a Titan aerocapture vehicle in expansion tubes

Development of heat transfer gauges for the measurement of radiant energy is currently being undertaken at The University of Queensland. The gauges incorporate up to two thin film heat transfer sensors which are separated from direct contact with the flow by appropriate optical glass. Cylindrical brass holders were designed as the housing for the radiation gauges with the inside cavity painted in flat black to minimise spurious reflections. Once assembled, the gauges were mounted at the stagnation point of a 70 degrees sphere-cone with an angle of attck of 16 degrees, along with two fast response thermocouples which were directly exposed to the flow. An approximate view factor of 0.046 was calculated by considering the geometry and transmission of the optical windows. Preliminary results indicate that the radiative heat transfer has been successfully isolated from the total heat transfer in expansion tube subscale models, when subjected to a simulated aerocapture manoeuvre at Titan.