High-Enthalpy Aerothermodynamics of a Mars Entry Vehicle Part 1: Experimental Results

Abstract

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

Experimental and Numerical Investigation of Hypervelocity Carbon Dioxide Flow over Blunt Bodies

“…For a configuration with a similar corner-nose radius ratio as the MSL, Stewart and Chen reported a 13.76% difference between the experiment and the simulation [3]. For the Pathfinder geometry (70 deg sphere cone), Hollis and Perkins measured heat transfer on Macor models using palladium thin-film gauges [7]. Computed forebody heating rates agreed well with measurements, except those readings near the stagnation point [45].…”

“…Hollis and Perkins compared various sphere-cone model forebody and aftbody heat transfer values with computational simulations in the NASA Hypersonic Pulse facility expansion tube [6,7] and the 31 in. Mach 10 Langley wind tunnel [6].…”

Evaluation of Hypervelocity Carbon Dioxide Blunt Body Experiments in an Expansion Tube Facility

“…6 For the Pathfinder geometry (70-degree sphere cone), Hollis and Perkins measured heat transfer on Macor models using palladium thin-film gauges. 9 Computed forebody heating rates agreed well with measurements except those readings near the stagnation point. grid and uncertainties in the physical models.…”

“…1 In the reflected shock tunnel HEG, CO 2 flow over a 70-degree blunt cone was studied using simulations and experiments by Netterfield et al 7 Hollis and Perkins compared various sphere-cone model forebody and aftbody heat transfer values with computational simulations in the HYPULSE expansion tube 8,9 and the 31-inch Mach 10 Langley wind tunnel. 8 Overall, very good agreement between CFD and experiment was achieved.…”

Survey of high-enthalpy shock facilities in the perspective of radiation and chemical kinetics investigations

“…HYPULSE is also used for aerothermodynamics testing related to atmospheric entry. Most of the work done for this purpose has been focused to duplicate Mars [127][128][129] for investigating the wake flow of the capsule. Wake and forebody heating rates were measured.…”