Nozzle Forced Shock Oscillations (Holger Babinsky)

Introduction

In the present study, the response to periodic forcing of a normal shock wave in a parallel walled channel has been investigated. Attention has been focused on the interaction between the normal shock wave and the turbulent boundary layer developing on the tunnel floor. The main aim of the study is to characterise the unsteady behaviour of the interaction and to identify the key factors that influence its nature. Tests with freestream Mach numbers ahead of the shock wave of 1.3, 1.4 and 1.5 have been conducted to investigate interactions with varying degrees of shock induced boundary layer separation. Experiments without forcing have also been conducted to provide a basis for comparison. The effects of flow control devices – in the form of mechanical micro-vane vortex generators – on the steady and oscillating interaction have also been studied.

CFD was performed in the form of unsteady RANS calculations for the steady and unsteady flow without control at Mach numbers 1.3 and 1.4. A number of turbulence models were applied. In the case of M = 1.3, one further simulation was performed using DES. During the course of the investigation it was found that a converged solution could not be achieved for the strong shock case (M = 1.5). It is suggested that this is due to corner effects.