Heat Flux Measurements in Radiation and Arcjet Furnaces and In-situ Ablation Experiments with X-ray Tomography

Kurzfassung

A spacecraft entering an atmosphere experiences high heat fluxes giving rise to the need of thermal protection systems. Materials necessary for thermal protection are investigated in various ground facilities and one of the important parameters that has to be computed is the heat flux at the stagnation region. The heat flux envelope of the mini-radiation and arc-jet facilities using a copper cylinder probe is investigated in this thesis. The heat flux probe used in the investigation was calibrated against a null point calorimeter; tests were conducted by permuting different parameters and the effect of the varied parameter was studied. The variation in static chamber pressure was found to be the major contributor in the fluctuation of heat flux in both the facilities. The radiative heat flux investigation tests allowed to conduct in-situ ablation tests. The in-situ ablative tests with X-ray tomography were done for DLR-cork and ZURAM materials. The tests further showed the degradation of material inside the chamber on a real-time basis leading to better understanding of the structural changes in materials due to high directional heat loads. In-situ tests with the arc-jet facility and comparative studies using the same testing conditions with different material models will provide a good follow-up to this research.