Supersonic Base Flow With and Without Propulsive Jets: A Brief Review

Abstract

Supersonic base flow is encountered in many aerospace applications related to satellite launch vehicle, missiles and projectiles. The origin and evolution of large scale structures which govern the dynamics of the base flow is not properly understood. The presence of central propulsive jet further complicates the base flow characteristics. Different semi-empirical, experimental and numerical studies carried out in supersonic base flow is briefly reviewed. Various issues and challenges faced in CFD simulation of base flow problems are described. Apart from resolution of numerics, proper choice of turbulence model remains the key aspect in the Reynolds Averaged Navier Stokes (RANS) simulations. Prediction of axial distribution of centerline velocities and recirculation bubble size remain problematic in RANS simulation. Detached Eddy Simulation (DES) results show dependence on model constants. Large Eddy Simulation (LES) studies with proper filter and Sub Grid Scale (SGS) model is promising, but its applications are limited to canonical problems due to very high computational requirements. Direct Numerical Simulation (DNS) studies reported in the literature consider much lower Reynolds number and hence could not be compared with the experimental data. It is suggested to use RANS and DES methods with anchored turbulence model from well-designed experiments for design data generation. Efforts should be made to use higher order numerical methods (LES and DNS) to explore the origin and evolution of large scale structures observed in compressible base flow.