Flow characterization of a supersonic and hypersonic arc-heated wind tunnel

The University of Notre Dame arc-heated hypersonic wind tunnel, ACT-1, was built in 2015 to study combustion in the supersonic and hypersonic flow regimes. Since its construction, little has been done to assess its flow quality. A pitot-rake survey has now been conducted at multiple axial and radial stations for arc-off (stagnation temperature ≈ 295 K) conditions. For a stagnation pressure of 380 kPa, the average measured Mach number at the nozzle exit plane was 4.7 and 6.3 for the Mach-4.5 and-6 nozzles, respectively. The flow fields of both nozzles exhibited slight angularity and asymmetry. Kulite pressure transducers measured the spectral content of noise in the flow for frequencies up to 127.5 kHz. The root-mean-squared of the pitot pressure was found to be 2.2–2.4% and 0.5–2.2% of the mean pitot pressure for the Mach-4.5 and-6 nozzles, respectively. Measurements with a static pressure probe indicated that condensation prematurely shortened the axial length of the uniform flow region for the Mach-6 nozzle. This effect was larger at lower stagnation temperatures. No condensation was observed for the Mach-4.5 nozzle.