On the subsonic near-wake of a space launcher configuration without jet: Experimental investigation by means of particle image velocimetry (PIV) on the subsonic (Mach 0.5 to 0.9) near-wake flow of a space launcher configuration

摘要

Wake flows have been extensively investigated in the past mainly with the objective to reduce drag. The failure of Ariane 5 Flight 157 though revealed that the understanding has not been sufficient, which triggered a new series of base-flow investigations. Most of them scrutinized the dynamics of the flow at one specific point along the flight path either in the subsonic, transonic, or supersonic range. However, no coherent image of the flow topology development in terms of a parametric study is available so far. The current work addresses the question of a near-wake scaling of a generic space launcher configuration. This question is tackled experimentally by means of particle image velocimetry measurements in the vertical test section Cologne in the range of Mach 0.5, 0.6, 0.7, 0.8, and 0.9 for Reynolds numbers between ReD=0.8x106 and 1.7x106. Results show the mean, the turbulence intensity, and the Reynolds shear stress distribution in the wake in comparison with the literature. In addition, data to the incoming boundary layer are provided and to the evolving shear layer. In that regime, the results indicate that the velocity and Reynolds stresses might be independent from the Mach and Reynolds number if scaled with the reattachment length. If this hypothesis holds true, it might be useful for the validation of numerical codes and for the initial determination of the flow field of space launchers in the design phase.