真实气体效应对双楔绕流流动特性的影响

Influence of Real Gas Effect on Flow Characteristics of Double Wedge Flow

关键词:  真实气体效应  化学非平衡气体  高超声速边界层转捩  双楔绕流  分离流动

Key words:  Real gas effect  Chemical nonequilibrium gas  Hypersonic boundary layer transition  Double wedge flow  Separated flow

摘要:

为研究高马赫数下真实气体效应对双楔绕流流动特性的影响，采用量热完全气体模型和化学非平衡气体模型两种气体模型对层流流态、转捩流态、全湍流流态的双楔绕流流场进行了数值模拟，其中转捩流态计算采用基于间歇因子的γ-Reθt转捩模型，全湍流计算中采用k-ω SST湍流模型。结果表明：双楔拐角附近发生流动分离，与量热完全气体模型相比，相同流态下，化学非平衡气体模型计算得到的分离区尺寸更小。在边界层转捩位置的分析中发现，双楔拐角附近的分离区对边界层转捩有重要影响，分离激波产生的位置与边界层开始转捩的位置高度吻合，与量热完全气体模型相比，化学非平衡气体模型时的边界层转捩起始位置更靠后。针对真实气体效应下单位雷诺数、拐角角度对边界层转捩的影响规律研究发现，真实气体效应在一定程度上抑制了分离区内的转捩流动，随着单位雷诺数减小、拐角角度增大，真实气体效应对边界层转捩的影响随之增大。

Abstract:

In order to study the influence of real gas effect on the flow characteristics of double wedge flow at high Mach number， the effects of two gas models， including calorimetric complete gas model and chemical non-equilibrium gas model， and three typical boundary layer flow states， including laminar flow state， transition flow state and full turbulent flow state， on the flow field of double wedge structure are studied by numerical simulation. The γ-Reθt transition model based on the intermittency was used for the calculation of transition flow， and the k-ω SST turbulence model was used for the calculation of turbulence flow. The results show that flow separation occurs near the corner of the double wedge. Compared with the calorimetric complete gas model， the size of the separation zone calculated by the chemical nonequilibrium gas model is smaller under the same flow state. In the analysis of boundary layer transition position， it is found that the separation zone near the corner of the double wedge has an important influence on boundary layer transition， and the position of separation shock wave is highly consistent with the position of boundary layer transition. Compared with the calorimetric complete gas model， the initial position of boundary layer transition in the chemical nonequilibrium gas model is further back. According to the study of the effects of unit Reynolds number and corner angle on boundary layer transition under the real gas effect， it is found that the real gas effect inhibits the transition flow in the separation area to a certain extent. With the decrease of unit Reynolds number and the increase of corner angle， the influence of real gas effect on boundary layer transition increases.