High Performance Flow Modeling of Spacecraft and Atmospheric Vehicles Re-entry vehicles designed for space exploration are usually equipped with thermal protection systems (TPS) made of ablative material which is one of the key components of their design. Through the use of ablators the energy absorbed by the removal of material from the surface is not used to heat the TPS, thus keeping the vehicle at a relatively “cold” temperature. It is imperative to account for the gases produced by ablation processes; creating the need for an appropriate gas flow chemistry model to be included in the Computational Fluid Dynamics (CFD) calculations in order to properly model and predict the aerothermal environment of the vehicle. Models have been proposed in the past but important reactions were not included, and some of the reaction rates were inappropriate or simply outdated due to challenges in flow modeling features such as internal energy relaxation and chemical reactions. Because ablation coupling is becoming an increasingly important research topic, the development of an accurate, yet usable, chemistry model and its integration to an efficient CFD code is of great importance that can impact the commercial CFD market that is around $1B in size.
Coupled CFD Solver and Modeling of Flow, Surface Chemistry, and Material Response for High Speed Atmospheric Vehicles A multi-dimensional, parallel CFD code (LeMANS) for the simulation of weakly ionized hypersonic flows in thermo-chemical non-equilibrium has been developed by the researchers at the Dept. of Aerospace Engineering of the University of Michigan. It solves the Navier-Stokes equations with finite rate chemistry that uses the developed carbon-phenolic-air chemistry model and with internal energy relaxation on an unstructured mesh while enabling the use of a blowing boundary condition to also account for the ablating TPS. Because of the way LeMANS has been parallelized, the code remains efficient, robust and fast, even with the increased number of equations to solve. As a test case, the Stardust vehicle re-entry at 71 km CFD results demonstrated the efficiency of the significantly reduced model compared to equilibrium radiative boundary conditions. The proposed code is modular with components for flow, surface and material coupling that allows great flexibility in simulating different gases, and different geometries for analyzing the flow of gases under high temperature conditions.
Applications • analysis of very high speed flow of vehicles operating in our atmosphere • analysis of gas flow around spacecraft entering planetary atmospheres • analysis of gas flow of rockets and their plumes
Advantages • flexible, modular software with many options Advantages over current options • developed to run on multi-processor computer architectures