Flow structure and unsteadiness in the supersonic wake of a generic space launcher

Abstract

The wake flow of a generic axisymmetric space-launcher model with and without propulsive jet is investigated. Measurements are performed at Mach 2.9 and a Reynolds number Re D = 1.3 • 10 6 based on model diameter D, and the nozzle exit velocity of the jet is at Mach 2.5. Velocity measurements in the wake flow by means of Particle Image Velocimetry and mean and unsteady wall-pressure measurements on the main-body base are performed simultaneously. This way, the evolution of the wake flow was observed along with its spectral content. In this paper, the mean flow topology and turbulence behavior of the wake is described based on PIV measurements, and the influence of the afterexpanding jet plume is discussed. For the case without propulsive jet, a large separated zone is forming downstream of the main body shoulder and the flow is reattaching downstream on the nozzle fairing. Under the influence of the jet plume, the separated region is increased and reattachment does not occur anymore. The flow is displaced away from the wall. The jet plume appears to have a stabilizing effect on the wake flow. The development of the shear layer and the magnitude of the turbulent intensities are damped, which we showed with the axial and radial components of the turbulent velocity fluctuations, as well the Reynolds shear stress evolution along the launcher afterbody.