A method for the direct numerical simulation of hypersonic boundary-layer instability with finite-rate chemistry

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• 作者：Olaf Marxen ; Thierry E. Magin ; Eric S.G. Shaqfeh ; Gianluca Iaccarino
• 关键词：Navier&ndash ; Stokes equations ; Finite difference methods ; Instability of boundary layers ; Direct numerical simulations ; Supersonic and hypersonic flows ; Chemically reactive flows ; Viscosity ; diffusion ; and thermal conductivity ; Thermodynamic properties ; e
• 刊名：Journal of Computational Physics
• 出版年：2013
• 出版时间：15 December, 2013
• 年：2013
• 卷：255
• 期：Complete
• 页码：572-589
• 全文大小：684 K

文摘

A new numerical method is presented here that allows to consider chemically reacting gases during the direct numerical simulation of a hypersonic fluid flow. The method comprises the direct coupling of a solver for the fluid mechanical model and a library providing the physio-chemical model. The numerical method for the fluid mechanical model integrates the compressible Navier-Stokes equations using an explicit time advancement scheme and high-order finite differences. This Navier-Stokes code can be applied to the investigation of laminar-turbulent transition and boundary-layer instability. The numerical method for the physio-chemical model provides thermodynamic and transport properties for different gases as well as chemical production rates, while here we exclusively consider a five species air mixture. The new method is verified for a number of test cases at Mach 10, including the one-dimensional high-temperature flow downstream of a normal shock, a hypersonic chemical reacting boundary layer in local thermodynamic equilibrium and a hypersonic reacting boundary layer with finite-rate chemistry. We are able to confirm that the diffusion flux plays an important role for a high-temperature boundary layer in local thermodynamic equilibrium. Moreover, we demonstrate that the flow for a case previously considered as a benchmark for the investigation of non-equilibrium chemistry can be regarded as frozen. Finally, the new method is applied to investigate the effect of finite-rate chemistry on boundary layer instability by considering the downstream evolution of a small-amplitude wave and comparing results with those obtained for a frozen gas as well as a gas in local thermodynamic equilibrium.