Base-flow sensitivity of a generic rocket forebody towards small freestream angles

¹ Institute of Aeronautics and Astronautics, RWTH Aachen 7 Wüllnerstraße, Aachen 52062, Germany
² Institute of Aerodynamics and Flow Technology German Aerospace Center (DLR) 7 Lilienthalplatz, Braunschweig 38108, Germany 10 Bunsenstraße, Göttingen 37073, Germany

Abstract

Experimental and numerical investigations have been conducted regarding the wake flow of a generic rocket model in subsonic freestream conditions. The bluff base geometry evokes a recirculation area represented by counterrotating vortices. Experiments using Particle Image Velocimetry (PIV) demonstrate that the spatial organization of this area is heavily dependent on small freestream angles (α, β < 1°), associated with a significant shift in the base pressure distribution. Numerical studies using Reynolds-Averaged Navier-Stokes (RANS) methods with one- and twoequation turbulence models are able to predict the mean velocity field as well as tendencies regarding α and β, but lack the sensitivity of the experiments. The mean pressure level on the base is calculated within 10% of the experimental value using the two-equation turbulence model, although the pressure distributions on the base show distinct differences.