Analogy Between Vibrational and Chemical Nonequilibrium Effects on Stagnation Flows

摘要

The vibrational excitation and chemical reaction of diatomic molecules are two typical real gas effects that can significantly influence the flow and aeroheating characteristics of hypersonic vehicles, and the qualitative similarity between them has been observed long before. In this paper, based on the theoretical modeling method, a specific analogy of their effects on nonequilibrium stagnation flow is proposed. Therefore, the physical models and mathematical techniques employed in our previous studies on the chemical nonequilibrium flows can be extended to study the vibrational nonequilibrium effects that are dominant in the relatively lower-temperature flows. This analogy study introduces several nonequilibrium flow criteria and a formula that can be used to assess the vibrational nonequilibrium effects on stagnation point heat transfer to wall surfaces with an incomplete accommodation of the vibrational energy. The direct simulation Monte Carlo method is employed to validate the analytical results. This study could enrich the understanding of the nonequilibrium flow physics and similarity of the real gas flows.