PIV Measurements and Total Temperature Thermometry of a Mach 4.5 Arc-heated Nozzle Flow

PIV measurements were conducted in the Arc-Heated Combustion Tunnel (ACT-II), on a high enthalpy Mach 4.5 nozzle flow. The primary motivation of the current work is to establish the feasibility of PIV as a high-quality flow diagnostic technique in hypersonic arc-heated flows and produce a high-resolution hypersonic nozzle flow characterization, including boundary layer and free shear layer velocity profiles. Due to the uncertain nature of the gas composition of the flowfield of interest, PIV measurements using a wedge flow were used to couple the flow velocities to the oblique shock relations. This allowed for the introduction of a means of total temperature calculation driven by these PIV measurements that requires no a priori assumptions of gas composition. A PIV expansion module was developed for this study, and proper seed sizing and material selection was performed for the present flow. The resulting PIV measurements represent, to the authors’ best knowledge, the first PIV measurements taken in an arc-heated hypersonic wind tunnel, or even in a non-impulsive, non-vitiated high enthalpy (>1000 K) flow.