高超声速飞行器横流转捩机理及预测模式研究

The accurate prediction of boundary layer transition is crucial for the design of hypersonic vehicles’ aerodynamics, aerothermodynamics and inlet system. The crossflow instability is an important factor in inducing the three-dimensional (3D) hypersonic boundary layer transition. The direct numerical simulation will be used to analyze the crossflow-induced transition mechanism for hypersonic 3D boundary layer flow. The receptivity of stationary crossflow, disturbance growth rates, wavelength evolution, crossflow vortex coalescence and the interaction with streamwise instability will be studied. After that, the crossflow timescale will be formulated, and the first and second Mack mode timescales will be coupled, and the intermittency transport equation will also be introduced to construct the crossflow transition model. The formulation of the crossflow timescale will be based on transition physical mechanism, and the acquisition of boundary layer parameters will be realized by using the proposed computational scheme which is suitable for modern CFD method. Boundary layer transition on the hypersonic vehicle forebody and complex whole body will be predicted by using the crossflow transition model. The effects of transition on hypersonic vehicles’ aerodynamics, aerothermodynamics and inlet system will also be analyzed. The research work carried out will not only help to improve the prediction accuracy of hypersonic boundary layer transition, but also provide reference for a variety of studied on transition mechanism and the construction of transition prediction methods, and will have important academic significance and practical value.

准确预测边界层转捩对高超声速飞行器气动力/热和进气道系统的合理设计至关重要，其中横流不稳定是诱导高超声速飞行器三维边界层转捩的重要因素。通过直接数值模拟分析高超声速三维边界层横流转捩机理，研究横流驻涡模态扰动的感受性、扰动增长率和波长的演化机制、横流涡融合现象以及与流向不稳定的交互作用。以此为基础，构造横流模态时间尺度，耦合第一、第二Mack模态时间尺度，引入间歇因子输运方程，实现横流转捩模式的构造。其中横流模态时间尺度构造考虑横流转捩机理，其所需边界层参数通过提出的一种适用于现代CFD方法的计算方案获取。采用所构造的横流转捩模式完成对高超声速飞行器前体和复杂全机外形的边界层转捩预测，并分析转捩对飞行器气动力/热和进气道系统的影响。所开展的研究工作不仅有助于提高高超声速飞行器边界层转捩的预测精度，同时能够为多种转捩机理研究、转捩预测方法构造提供借鉴思路，具有重要的学术意义和工程实用价值。

准确预测边界层转捩对高超声速飞行器气动力/热和进气道系统的合理设计至关重要，其中横流不稳定是诱导高超声速飞行器三维边界层转捩的重要因素。通过高阶数值格式计算获得了HIFiRE-5外形三维边界层横流涡的演化过程，观察到横流涡的线性增长阶段，并解释了横流涡融合现象。之后，构造横流模态时间尺度，耦合第一、第二Mack模态时间尺度，引入间歇因子输运方程，实现了横流转捩模式的构造。其中横流模态时间尺度构造考虑了横流转捩机理，其所需边界层参数通过提出的一种适用于现代CFD方法的计算方案获取。采用所构造的横流转捩模式完成了对高超声速飞行器前体和复杂全机外形的边界层转捩预测，并分析了转捩对飞行器气动力/热和进气道系统的影响。所开展的研究工作不仅有助于提高高超声速飞行器边界层转捩的预测精度，同时能够为多种转捩机理研究、转捩预测方法构造提供借鉴思路，具有重要的学术意义和工程实用价值。