Physico Chemical Modelling in Hypersonic Flow Simulation

Abstract

The rapid and significant advances in computational power both in terms of hardware and software in recent years and the resurgence in 1980's of interest in future concepts for hypersonic transportation systems and ongoing studies such as those for the International Space Station, Shuttle-like orbital vehicles (Japanese HOPE), reusable launch vehicles (NASA X-33, X-34), and crew rescue vehicles (NASA X-38) have identified Computational Fluid Dynamics (CFD) as an important and indispensable tool for R & D in the field. To take advantage of this valuable tool for reliable simulations and predictions one must pay careful attention to the quality and validity of the modelling inputs that go into the development of the CFD codes while striving to improve their numerical accuracy and algorithmic efficiency. A review of the governing equations, boundary conditions and the associated inputs by way of physico-chemical models and their partially successful application is given. Some of the 'rate-limiting' steps in achieving predictive capability via CFD are related to inadequacies in the physico-chemical models and in associated data used in describing the multi-species high-temperature chemically reacting gas flows occurring in and around hypersonic vehicles. A few of these continuing modelling challenges are briefly reviewed here with typical examples from current literature.