Numerical simulation of flow field over slender bodies at transonic Mach number and low angle of attacks

Abstract

The transonic flow field over a launch vehicle is complicated due to presence of a normal shockwave on the heat shield. To predict the aerodynamic loads, the shockwave position needs to be predicted accurately. The present work aims at predicting the flow field over a typical launch vehicle at an angle of attack (AOA), and analyzing the effect of AOA on flow field, shockwave position and aerodynamic and moment coefficients. The launch vehicle considered here is a long slender body with spherical nose followed by the conical, cylindrical and boat-tail portions. Simulations are performed at a Mach number of 0.95with AOA of 0°, 2°, and 4°. Commercial Computational Fluid Dynamics package ANSYS Fluent is used for simulations. Density-based algorithm is used to obtain the steady state solutions with explicit time stepping.κ-ω SST turbulence model is used to close the turbulent stresses terms. The surface pressure distribution in axial direction is analyzed to understand the effect of AOA on the aerodynamic and moment coefficients. It is observed that as AOA increases, the normal shockwave moves towards nose. The drag coefficient and pitching moment coefficients are found to increase with increase of AOA.