Numerical simulation of hypersonic reaction flows with nonlinear coupled constitutive relations

As all known, there exists extremely thermal and chemical non-equilibrium phenomenon in hypersonic flows. Much effort has been put into the development of computational models for the prediction of such non-equilibrium flow. In order to obtain the real physical solution of the challenging non-equilibrium problems, Eu proposed a set of generalized hydrodynamic equations (GHE) from the viewpoint of generalized hydrodynamics. Based on Eu's GHE equations, Myong developed an efficient computational model, named as the nonlinear coupled constitutive relations (NCCR). The present study is based on the 3-D FVM NCCR model in conjunction with 7-species chemical reaction model to consider the reacting gas effect for hypersonic reentry vehicles. For further examining the performance of the proposed computational model, the typical engineering cases of Radio Attenuation Measurements (RAM)-C II vehicle are adopted. The flow contours, distribution profiles along stagnation line and surface properties are compared between nonlinear coupled constitutive model and those of the Navier-Stokes equation. The accuracy and physical consistency of the NCCR model are critically examined and validated for hypersonic reaction flow in the continuum region. For the near continuum region, the NCCR model can predict non-equilibrium phenomenon more accurately than NS equation through the comparison of shock standoff distance and electron number density. The comparisons between NCCR model with one component perfect gas and multi-species reacting gas effect are also made to show the importance of chemical reaction source term. (C) 2021 Elsevier Masson SAS. All rights reserved.

Automated summary

Efforts have been made to develop computational models for predicting non-equilibrium flow in hypersonic flows. A generalized hydrodynamic equations (GHE) and a nonlinear coupled constitutive relations (NCCR) model have been proposed for this purpose. The NCCR model shows better accuracy in predicting non-equilibrium phenomena compared to the Navier-Stokes equation, especially in the near continuum region. The importance of the chemical reaction source term in the NCCR model is also demonstrated through comparisons with different gas models.