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Influence of a propulsive jet on the wake-flow structure of an axisymmetric space-launcher model

Anne-Marie Schreyer
Institute of Fluid Mechanics TU Braunschweig 38108 Braunschweig, Germany; Institute of Aerodynamics, RWTH Aachen University, 52062 Aachen, Germany

Abstract

We investigate the influence of an afterexpanding propulsive jet on the wake flow of a generic axisymmetric space-launcher model at a Mach number of M = 2.9 and a Reynolds number of ReD = 1.3 × 106, based on model diameter D. The description and discussion of turbulent structures in the wake flow, as well as the influence of a propulsive jet on their dynamic behavior is the focus of this study. The mean and turbulent flow topology and the dynamics of the wake are analyzed based on experimental data from Particle Image Velocimetry (PIV) measurements, Schlieren visualizations, and measurements of surface-pressure fluctuations. The data are interpreted with a combination of classical statistical analysis and post processing by means of Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD). By combining the strengths of these different methods, we intend to improve the understanding of the mechanisms in the wake instability. In particular, we discuss the influence of the jet plume on the growth of vortices in the shear layer forming at the shoulder of the main body. Understanding this behavior will ultimately contribute to more efficient launcher designs and thus affordable access to space.