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

Abstract

Numerical simulations of the near wake of generic rocket con¦gurations are performed at transonic and supersonic freestream conditions to improve the understanding of the highly intricate near wake structures. The Reynolds number in both §ow regimes is 10 6 based on the main body diameter, i. e., speci¦c 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 §ow. A zonal approach consisting of a Reynolds averaged NavierStokes (RANS) and a large-eddy simulation (LES) is applied. It is shown that the highly unsteady transonic wake §ow at Ma ∞ = 0.7 is characterized by the expanding separated shear layer, while the Mach 6.0 wake is de¦ned by a shock, expansion waves, and a recompression region. In both cases, an instantaneous view on the base characteristics reveals complex azimuthal §ow structures even for axisymmetric geometries. The §ow regimes are discussed by comparing the aerodynamic characteristics, such as the size of the recirculation region and the turbulent kinetic energy.

Characterization of pressure dynamics in an axisymmetric separating/reattaching flow using fast-responding pressure-sensitive paint

“…These results are in good agreement with the numerical investigations by Statnikov et al (2012). However, the numerical prediction of a mode-like structure on the base of the configuration could not be validated experimentally so far.…”

“…The node number for the entire mesh was 60 Â 10 6 . Further details of the numerical approaches and models can be found in Statnikov et al (2012). The comparison of both figures shows a good agreement in the magnitudes of the predicted pressure-and velocity fields.…”

“…The pressure distribution on the sting and the base was measured with fast-responding pressure-sensitive paint and the velocity magnitude in the x-z-plane was acquired with timeresolved particle-image velocimetry (data from Bitter et al (2011)) Fig. 23 Flow field in the near-wake region gathered from large-eddysimulation, provided with courtesy of Statnikov et al (2012) optical measurement techniques. Certainly, the reattachment length is over-predicted by about 25 % by the largeeddy-simulations as a result of the different turbulence levels between experiment and simulations.…”

“…Large-eddy flow simulations, which were performed by project partners (Statnikov et al (2012)), indicated a modelike 60°-distribution of the base pressure fluctuations p 0 . In order to identify a potential dominant radial wavelength, the pressure fluctuation signal shown in Fig.…”

“…23 reflect the ensembleaveraged data, which was extracted from large-eddy-simulations (LES) provided by project partners, see Statnikov et al (2012). The time-averaging was performed over 136 LES time steps.…”