Aerodynamic heating tests were conducted on a 70-deg sphere-cone Mars entry vehicle con guration in a high-enthalpy impulse facility in both carbon dioxide and air test gases. The purpose of these tests was to obtain heat transfer data for comparison with results of Navier-Stokes computations. Surface heat transfer rates were determined for both the forebody and afterbody of the test models and for the stings that supported the models in the facility test section. Little difference was observed between normalized heating distributions for the air and carbon dioxide test conditions. For both cases, peak sting heating was on the order of 4-5% of the forebody stagnation-pointheating, and it was concluded that the wake ow remained laminar. The wake ow establishment process was quanti ed and was found to require approximately 40-70 ow path lengths, which corresponded to approximately 75% of the available facility test time. The repeatability of facility test conditions was estimated to vary between § 3% and § 10%. The overall experimental uncertainty of the data was estimated to be § 10-11% for forebody heating and § 17-22% for wake heating. NomenclatureB = measurement bias error h = enthalpy, J/kg k = thermal conductivity, W/m ¢ K M = Mach number P = measurement precision error p = pressure, N/m 2 q = heat transfer rate, W/m 2 R = radius, m Re = Reynolds number S = distance along model surface, m T = temperature, K t = time, s U 1 = freestream velocity, m/s U tot = total combined uncertainty y ref = reference length, m ® = thermal diffusivity, m 2 /s = thermal product, ®/ p k, W ¢ s 1=2 /m 2 ¢ Ķ = correction factor, K ¡1 ½ = density, kg/m 3 ¾ = heat transfer residual ¿ = nondimensional time, U 1 1t est =y ref Subscripts est = establishment w = wall 0 = stagnation 1 = freestream 2 = post-normal shock

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Detailed measurements of aerodynamic heating rates in the wake of a Mars-Pathfinder configuration model have been made. Heating data were obtained in a conventional wind tunnel, the NASA LaRC 31" Mach 10 Air Tunnel, and in a high-enthalpy impulse facility, the NASA HYPULSE expansion tube, in which air and CO 2 were employed as test gases. The enthalpy levels were 0.7 MJ/kg in the Mach 10 Tunnel, 12 MJ/kg at Mach 9.8 for HYPULSE CO 2 tests and 14 MJ/kg at Mach 7.9 for HYPULSE air tests. Wake heating rates were also measured on three similar parametric configurations, and forebody heating measurements were made in order to facilitate CFD comparisons. The ratio of peak wake heating to forebody stagnation point heating in the Mach 10 Tunnel varied from 7% to 15% depending on the freestream Reynolds number. In HYPULSE, the ratio was ~5% for both air and CO 2 . It was observed that an increase in the ratio of forebody corner radius to nose radius resulted in a decrease in peak wake heating, and moved the peak closer to the base of the forebody. The wake flow establishment process in HYPULSE was studied, and a method was developed to determine when the wake has become fully established. BACKGROUND

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A series of aerodynamic heating tests was conducted on a 70-deg sphere-cone planetary entry vehicle model in a Mach 10 perfect-gas wind tunnel at freestream Reynolds numbers based on diameter of 8.23x10 4 to 3.15x10 5 . Surface heating distributions were determined from temperature time-histories measured on the model and on its support sting using thin-film resistance gages. The experimental heating data were compared to computations made using an axisymmetric/2D, laminar, perfect-gas Navier-Stokes solver. Agreement between computational and experimental heating distributions to within, or slightly greater than, the experimental uncertainty was obtained on the forebody and afterbody of the entry vehicle as well as on the sting upstream of the free-shear-layer reattachment point. However, the distributions began to diverge near the reattachment point, with the experimental heating becoming increasingly greater than the computed heating with distance downstream from the reattachment point. It was concluded that this divergence was due to transition of the wake free shear layer just upstream of the reattachment point on the sting. Nomenclature B C,Hheating bias error