Numerical Assessment of an Aerodynamic Probe to Enable Short Focal Length Laser Diagnostics in High Temperature Supersonic Flows Based on Flow Disturbance

Abstract

This article evaluates the use of an actively cooled aerodynamic probe body with integrated optics to perform short focal length laser diagnostics within high-temperature, high-supersonic flows. A novel probe with a “ship's bow” shape and an open cycle cooling scheme ending in a matrix of effusion holes is presented. The flow around the probe is studied numerically using 3D steady Reynolds-averaged Navier–Stokes (RANS) simulations at Mach 6, with freestream total conditions of 1700 K and 44.2 bar. The laser trajectory is calculated using the ray propagation equation to ensure that it deviates minimally while going through regions of gradients in refractive index. The location and shape of the detached shock formed ahead of the probe is extracted, and the minimum focal length achievable for measurement of the undisturbed flow field is determined. The sensitivity of the bow shock shape to changes in cooling pressure between 1.33 and 1.835 bar and to blocked holes has been computed. Finally, the flow through the effusion system of the probe is tested experimentally, ensuring its proper operation, and checking the consistency of the effusion boundary conditions used in the numerical study.