Venus Entry Flow over a Decomposing Aeroshell in X2 Expansion Tube

The effects of phenolic decomposition on shock-layer radiation were investigated experimentally in X2 expansion tube for a Venus entry flow. A carbon–phenolic composite aeroshell was subjected to a flow with a flight equivalent velocity of 9.35  km⋅s−1. Emission spectroscopy was used to measure boundary-layer radiation in parts of the ultraviolet (380–480 nm) and visible (620–700 nm) spectrum, and it was compared to control measurements taken with a cold steel model. With the composite model in place, the calibrated spectral radiance measured was seen to increase for the O (645.598 nm) atomic line and the N2+ (391.22 nm) band head, but it decreased for the C2 Swan band (420–480 nm). The recorded data were then compared to numerical spectra produced by two-dimensional axisymmetric computational fluid dynamic simulations coupled to a radiation solver. Both of the applied chemistry models overpredicted CN violet Δν=0 band radiation, which demonstrated strong self-absorption at these conditions. Better compar...

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