Numerical Base Heating Sensitivity Study for a Four-Rocket Engine Core Configuration

Abstract

In support of launch vehicle plume-induced base heating and pressure prediction efforts using the Loci-CHEM Navier–Stokes computational fluid dynamics solver, numerical simulations of a wind-tunnel test have been modeled and analyzed. This missile forebody test article is composed of four JP-4/LOX 500 lbf water-cooled rocket engines exhausting into a Mach 2–3.5 wind tunnel at various freestream pressure conditions. This study explores the base heating sensitivity for varying boundary conditions and various chemistry, turbulence, and thermodynamic models. The numerical solutions have been investigated at two freestream pressure conditions: (simulated low altitude) and (simulated high altitude). It is observed that the convective base heat flux and base temperature are most sensitive to the nozzle inner wall thermal boundary-layer profile, which is dependent on the wall temperature, boundary layer’s specific energy, jet expansion ratio, and chemical reactions. Recovery shock and wall jet dynamics and afterburning within the updraft plume also significantly influence convective base heating. Turbulence modeling shows less sensitivity to base heating characteristics. Base heating rates are validated for the highest-fidelity predictions, which show an agreement within with respect to test data.