Expansion Tunnel Ablation Testing in Venus Entry Conditions

The effects of phenolic pyrolysis on flow radiation were investigated experimentally in the X2 expansion tube for a Venus entry flow. A carbon phenolic aeroshell was subjected to a flow with a flight equivalent velocity of 9.59 km/s. Emission spectroscopy was used to measure boundary layer radiation in part of the visible wavelength range (615-700 nm) and compared to measurements taken with a cold steel model. The spectral radiance measured of the carbon phenolic model was seen to increase for C (658.942 nm) and N (672.262 nm) atomic lines, demonstrably due to surface reactions and outgassing. These experimental spectra were compared to numerical spectra produced by 2D axisymmetric CFD simulations coupled to a radiation solver.