Nonintrusive Pressure and Temperature Measurements in an Underexpanded Sonic Jet Flowfield

Abstract

Nonintrusive pressure and temperature measurements are performed in the flowfield of an underexpanded sonic jet using high-resolution nitrogen coherent anti-Stokes Raman scattering (CARS). The jet is operated with a fully expanded jet Mach number of 1.83. The time-averaged CARS measurements start at the jet exit and are spatially well resolved, elucidating the near-field shock structure of the jet. For example, the location of the Mach disk is resolved to within 350 μm. Downstream of the Mach disk, viscous effects cause the slip line between the inner and outer jet regions to transition to an annular shear layer. The measurements also define the curved outer shear layer bounding the jet. The experimental pressure and temperature data are compared to similar quantities extracted from a Reynolds-averaged Navier-Stokes computational-fluid-dynamic (RANS CFD) simulation of the flowfield