Measurements to Assess the Degree of Thermal Nonequilibrium at AEDC Hypervelocity Wind Tunnel No. 9

Recent hypersonic computational fluid dynamics (CFD) validation efforts within AIAA have identified a possible thermal nonequilibrium issue with hypersonic facilities that use nitrogen as the working fluid. Since the Arnold Engineering Development Center’s (AEDC) Hypervelocity Wind Tunnel No. 9 facility uses nitrogen as the working fluid, a computational and experimental program has been developed to identify and quantify the extent to which thermal nonequilibrium effects may impact the flow conditions in Tunnel 9. This paper describes the overall approach and status of this program as well as some experimental data collected in Tunnel 9, including heat-transfer rate on sharp cones as well as vibrational temperature via a Coherent Anti-Stokes Raman Spectroscopy (CARS) measurement. Preliminary analyses of all data show that thermal nonequilibrium effects do not appear to be on a measurable level in Tunnel 9.