Characterization of freestream Reynolds number influence on flow unsteadiness behind Shock/Boundary-Layer iInteraction in shock tube

Shock tubes are devices capable of generating shock waves and instantaneous aerothemodynamics phenomena. Compression waves are formed by rupturing the diaphragm in the tube, which reflects at the end wall and generates a region of high pressure and temperature. However, the reflected shock and a boundary layer on the tube causes a Shock/Boundary-Layer Interactions (SBLIs), which induces the flow unsteadiness. Previous research shows that this creates pressure growth and a shock-bifurcation in the reflected shock wave, inducing non-uniformity in the flow conditions behind the reflected shock. This work expands upon previous research which investigated the influence of freestream Reynolds number on non-ideal effects behind the reflected shock. The effects are characterized by the High-Speed Aerothermodynamics Laboratory’s shock tube facility at the University of Hawaii at Manoa. High speed schlieren-imaging and piezoelectric pressure transducers are utilized for characterizing shock wave structure and pressure fluctuations around the SBLI. Previous research suggests that increasing freestream Reynolds number and decreasing shock Mach number decreases non-ideal pressure fluctuations and bifurcation growth due to the SBLI. In this research, characterization of the freestream Reynolds number influence on the flow unsteadiness behind the SBLI in the shock tube is investigated experimentally for shock Mach numbers from 1.4 to 1.8.