Computational study of hypersonic double-cone experiments for code validation

Numerical methods are used extensively for the solution of the coupled gas-dynamic and gaskinetic equations that describe hypersonic flows with chemical reactions and nonequilibrium phenomena. Modern computational fluid dynamics (CFD) codes used for numerical simulations employ various models that describe physical phenomena such as energy relaxation, chemical reaction rates and diffusion processes. Additionally, novel algorithms have been developed for the efficient implementation of the numerical methods of solution on parallel computers. The objective of this work is to assess the ability of current state-of-the-art methods to simulate challenging hypersonic flow problems by comparing to well characterized experiments. This process involves simulation of experiments performed in inert environments, aiming to evaluate the quality of the numerics, followed by simulations of reacting flow experiments aiming to evaluate the accuracy of physical models. In this work, hypersonic double-cone flows are studied. The hypersonic flow past a double-cone model is a good test for numerical methods because it produces a very complicated shock interaction, and it requires a large number of grid points to simulate accurately. This thesis focuses on the simulation of a series of double-cone experiments performed at the Large Energy National Shock (LENS) facility using a reflected shock tunnel and an expansion tunnel. Simulations of experiments at low enthalpy showed very good agreement with measurements, and the discrepancies observed initially between numerical predictions and the experimental measurements were largely a result of having vibrational energy frozen in the free-stream. Simulations of high enthalpy experiments showed good agreement for nitrogen flows, and only qualitative agreement for air flows.