Consistent Chemical Kinetics and Continuum Models for High Temperature Air

Abstract

High-fidelity nonequilibrium reaction models for hypersonic air flow are developed. Hypersonic flows create shock waves, which compress and heat the surrounding gas to high-temperatures. Strong shock waves cause dissociation of nitrogen and oxygen molecules. Predicting the extent of dissociation and recombination of atomic species is important since the state of the gas near the vehicle surface determines heating rates and gas-surface chemistry that damages the heat shield. Since experimental data is difficult to obtain under such extreme conditions, numerical simulation plays an important role. Predictive numerical simulations require accurate reaction chemistry models. Computational models developed thus far range from simple empirical models fit to limited experimental data to models with millions of input parameters that track individual quantized energy state transitions. The level of model fidelity required for accurate engineering analysis remains an open question of active research. Models coupling internal energy and dissociation chemistry tend to be developed at either the kinetic scale or the continuum scale. In this dissertation, we develop new nonequilibrium models for shock heated flows that are analytically consistent between kinetic and continuum formulations, and are based on recent ab-initio data.