Numerical investigation of the near wake of generic space launcher systems at transonic and supersonic flows

Institute of Aerodynamics Aachen RWTH Aachen University 5a Wüllnerstrasse, Aachen 52062, Germany

Abstract

Numerical simulations of the near wake of generic rocket configurations are performed at transonic and supersonic freestream conditions to improve the understanding of the highly intricate near wake structures. The Reynolds number in both flow regimes is 10⁶ based on the main body diameter, i. e., specific freestream conditions of ESA's Ariane launcher trajectory. The geometry matches models used in experiments in the framework of the German Transregional Collaborative Research Center TRR40. Both axisymmetric wind tunnel models possess cylindrical sting supports, representing a nozzle to allow investigations of a less disturbed wake flow. A zonal approach consisting of a Reynolds averaged Navier-Stokes (RANS) and a large-eddy simulation (LES) is applied. It is shown that the highly unsteady transonic wake flow at Ma_∞ = 0.7 is characterized by the expanding separated shear layer, while the Mach 6.0 wake is defined by a shock, expansion waves, and a recompression region. In both cases, an instantaneous view on the base characteristics reveals complex azimuthal flow structures even for axisymmetric geometries. The flow regimes are discussed by comparing the aerodynamic characteristics, such as the size of the recirculation region and the turbulent kinetic energy.