Blunt-Body Heating and Pressure Database from High-Enthalpy, CO₂ Testing in an Expansion Tunnel

Abstract

An extensive database of heating, pressure, and flow field measurements on a 70-deg sphere-cone blunt body geometry in high-enthalpy, CO 2 flow has been generated through testing in an expansion tunnel. This database is intended to support development and validation of computational tools and methods to be employed in the design of future Mars missions. The test was conducted in an expansion tunnel in order to avoid uncertainties in the definition of free stream conditions noted in previous studies performed in reflected shock tunnels. Data were obtained across a wide range of test velocity/density conditions that produced various physical phenomena of interest, including laminar and transitional/turbulent boundary layers, non-reacting to completely dissociated post-shock gas composition and shock-layer radiation. Flow field computations were performed at the test conditions and comparisons were made with the experimental data. Based on these comparisons, it is recommended that computational uncertainties on surface heating and pressure for laminar, reacting-gas environments can be reduced to ±10% and ±5%, respectively. However, for flows with turbulence and shock-layer radiation, sufficient validation-quality data were not obtained in this study to make any conclusions with respect to uncertainties for those phenomena, which highlights the need for further research in these areas. NomenclatureA f,j = rate coefficient for forward reaction j (m 3 /kmol.s) D f,j = characteristic temperature of forward reaction j (K) H 0 = total enthalpy (J/kg) H w = wall enthalpy (J/kg) K c = equilibrium constant (-) or (kmol/m 3 ) k b,j = backward rate for reaction j (m 3 /kmol.s) or (m 6 /kmol 2 .s) k f,j = forward rate for reaction j (m 3 /kmol.s) M ∞ = free stream Mach number P ∞ = free stream pressure (Pa) P 0,2 = post-shock pitot pressure (Pa) q w = heat-transfer rate at the wall (W/m 2 ) Re ∞,D = free stream Reynolds Number based on diameter -ρ ∞ U ∞ D/μ ∞ Reθ = momentum thickness Reynolds Number -ρ e U e θ/μ e T a,j = controlling temperature for forward reaction j (K) T ∞ = free stream temperature (K) T w = wall temperature (K) U ∞ = free stream velocity (m/s) * Associate Fellow AIAA, Senior Technical Lead, Aerothermodynamics Branch, Research Directorate † Associate Fellow AIAA, Senior Scientist ‡ Senior Member AIAA, Senior Research Scientist Downloaded by PURDUE UNIVERSITY on June 25, 2016 | http://arc.aiaa.org |