Laser-induced schliere anemometry in a Mach 6 flow with collinear light entry

Abstract

In this work, we demonstrate velocity, Mach number, and static temperature measurements in a Mach 6 flow using the recently developed laser-induced schliere anemometry (LISA) technique. To our best knowledge, this represents the first application of LISA for characterizing flow in the hypersonic Mach number regime, and a comparison with known tunnel values is provided. The laser-induced schliere in this work are written from a distance of roughly 76 cm away from the final lens, much further than in previous work. Furthermore, the schliere are created from a laser beam introduced parallel to the collimated schlieren light, which is a new arrangement that could be useful for facilities with limited optical access. A discussion of setup limitations is provided. The mean core flow velocity determined from LISA is within 1% of the expected value from isentropic theory, while the mean Mach number measurements are within 1.6% of the M = 5.85 value used in literature for the facility. Furthermore, the determined mean static temperature of the core flow is within 2.5% of the value measured simultaneously in the facility.