Computations of Separated High-Enthalpy Hypersonic Flows: Development of RANS and Variable-Resolution PANS Approaches

We propose the development of a high fidelity computational approach for unsteady calculations of strongly separated non-equilibrium high-enthalpy hypersonic flows. The goal is to integrate the now proven partially-averaged Navier-Stokes (PANS) method for unsteady flow simulations with the most advanced closure models for compressibility, high-enthalpy (flow - thermodynamics coupling) and non-equilibrium (flow - chemistry coupling) effects. The PANS model has been established as a reliable model for computing separation in low and high speed regimes in two recently conclude NASA NRA projects -- 1. RANS and PANS modeling of hypersonic turbulent mixing environment; 2. Modeling of strongly separated flows with the PANS bridging method. The current proposal is to incorporate further hypersonic effect closures into PANS. Physics-based closure models for flow-thermochemistry interactions have been under development in Girimaji's group at Texas A & M under AFOSR MURI funding -- Transition and Turbulence modeling in non-thermochemical-equilibrium hypersonic flows. Important closure model building blocks for hypersonic processes are now available from the above fundamental research efforts. The combination of PANS and these advanced high-speed models will lead to a unique capability for computing hypersonic flow separation with ablation, chemistry and compressibility effects. For Phase I, we propose a logical sequence of verification-validation computations to demonstrate the potential of the various individual closures in separated high-speed high-enthalpy flows. While in-house codes are available for the proposed development, we will also consider using any of the NASA codes: USM3D, OVERFLOW, VULCAN or any of the other codes suggested by the grantor. Subsequent work (Phase II) will focus on the assembly of the individual components and development of an unique high-fidelity computational capability for hypersonic vehicle design, testing and development.