A comparative computational/experimental investigation of Mach 2 flow over a rearward-facing step

Abstract

A numerical study of the Mach 2 flow over a rearward-facing step was performed using the SPARK Navier-Stokes code as a companion to a comprehensive experimental investigation conducted at the University of Virginia using Laser-Induced Iodine Fluorescence (LIIF) and Laser Doppler Anemometry (LDA) techniques. Turbulence was modeled with the Baldwin-Lomax turbulence model. First, calculations of the Mach 2 nozzle were performed and excellent agreement was obtained between the calculated and measured velocity profiles one step height upstream of the step. Secondly, comparisons were made between the calculations and measurements obtained with both planar and pointwise fluorescence techniques for the rearward-facing step flow field. This study represents the first comparison between in-stream static temperature measurements and CFD calculations for supersonic flow over a rearward-facing step. Agreement between the planar measurements and the calculations was observed regarding the position of the prominent flow features: the expansion fan, the shear layer, and the reattachment shock. Significantly lower temperature measurements were observed in low-momentum regions of the flow field. Comparisons between the pointwise measurements and the calculations exhibited very good quantitative agreement. The calculated and measured pressures, temperatures and velocities agreed within 5% at approx. 85% of the experimental locations.