A separation control CFD validation test case part 2. Zero efflux oscillatory blowing

Abstract

The control of a separated flow over a wall-mounted hump, by means of two-dimensional zero efflux perturbations, was studied experimentally in order to generate a data set for a workshop aimed at validating CFD turbulence models. Part 1 of this paper considered details of the baseline (uncontrolled) case and a steady-suction control case. The data set for a specific zero efflux control case comprised static surface pressures together with phase-averaged dynamic surface pressures and PIV flowfield measurements. Additional static and dynamic surface pressures were acquired for a variety of control amplitudes, control frequencies and Reynolds numbers. Due consideration was given to characterizing the flow in the vicinity of the control slot, with and without external flow, and to perturbation two-dimensionality. Triple-decomposition of the fluctuating velocity and pressure fields was employed for presenting and analyzing the experimental data. This facilitated an assessment of the mechanism of separation control and the quantification of the coherent and turbulent surface pressures, Reynolds stresses and energy fluxes. Spanwise surface pressures and phase-averaged stereoscopic PIV data revealed an effectively two-dimensional flowfield despite highly three-dimensional instantaneous flow structures.