SUPERSONIC ABLATION STUDIES WITH TEFLON

The interaction of ablation and a vehicle's aerodynamic characteristics were studied. The test conditions involved stagnation pressured of 20 to 30 atmospheres, temperatures of 4000 to 9000 R and Mach numbers of 2.3 and 3. The test models, made of teflon, were instrumented for pressure, temperature, heat transfer, and skin- friction measurements. Laminar and turbulent boundary-layer data were obtained. The laminar data were compared with the predictions of a numerical procedure known as BLIMP-CMA. Close agreement was found between most of the experimental data and predictions. Ablation-induced transition was observed in all laminar runs. In fully turbulent runs cross- hatched striations were observed. Ablation reduced the wall shear stress by about 60 percent for the laminar runs and by 40 percent for the turbulent runs.