跨声速激波与三维层流边界层相互作用下横流转捩研究

most important flow types in aeronautics are three-dimensional boundary layers such as swept wings/cylinder, blades, small angle of attack cone, and rotating disk. The crossflow instability of a three-dimensional boundary layer is the main factor affecting the laminar transition. The three-dimensional boundary layer flow distorted by the saturated crossflow vortex is very sensitive to the high frequency disturbances, which foreshadows that the laminar transition will happen. In this project, the compressible crossflow secondary instability and transition will be investigated. A computation platform will be built based on linear stability theory(LST), nonlinear parabolized stability equations (NPSE), secondary linear stability theory (SLST) and direct numerical simulation (DNS) code. The interaction (secondary instability and transition) between the attached shockwave and 3-D boundary layer flow will be investigated when the free stream is transonic and the influence of Ma on the crossflow secondary instability will be considered by means of stability theoretical analyses. The effect of the wall cooling, heating, blowing and suction on the 3-D boundary layer crossflow secondary instability will be studied which will be the theory support for the drag reduction and thermal protection of modern aircraft.

三维边界层流动是航空工业中广泛存在的流动类型，例如后掠机翼/圆柱绕流、旋转叶片绕流、小攻角圆锥绕流和旋转圆盘流动等。横流失稳是三维边界层流动湍流转捩的主要因素，被饱和横流涡强烈扭曲的三维边界层背景流动对高频的扰动非常敏感，这也是三维边界层流动转捩发生的先兆。本课题将研究可压缩横流边界层的二次失稳与转捩，拟基于线性稳定性程序(LST)，非线性扰动方程抛物化方法(NPSE)、二次失稳理论(SLST)和直接数值模拟程序(DNS)建立一套流动稳定性与湍流转捩的计算与分析平台。本课题将研究在跨音速来流条件下，附体激波与三维层流边界层流动的相互作用对横流首次失稳、二次失稳和湍流转捩影响，以及来流马赫数对三维层流边界层二次失稳的影响。其次，本课题将研究壁面加热、冷却和吹吸气对可压缩三维边界层横流二次失稳的控制效果，为飞行器的减阻与热防护提供理论依据。

三维边界层流动是航空工业中广泛存在的流动类型，例如后掠机翼/圆柱绕流、旋转叶片绕流、小攻角圆锥绕流和旋转圆盘流动等。横流失稳是三维边界层流动湍流转捩的主要因素，被饱和横流涡强烈扭曲的三维边界层背景流动对高频的扰动非常敏感，这也是三维边界层流动转捩发生的先兆。本课题研究了可压缩横流边界层的二次失稳与转捩，基于线性稳定性程序(LST)，非线性扰动方程抛物化方法(NPSE)、二次失稳理论(SLST)和直接数值模拟程序(DNS)建立一套流动稳定性与湍流转捩的计算与分析平台。本课题研究了在跨音速来流条件下，附体激波与三维层流边界层流动的相互作用对横流首次失稳、二次失稳和湍流转捩影响，以及来流马赫数对三维层流边界层二次失稳的影响。其次，本课题将研究壁面加热、冷却和吹吸气对可压缩三维边界层横流二次失稳的控制效果，为飞行器的减阻与热防护提供理论依据。最后，本课题研究了在高Mach数情况下的来流噪声对高超横流转捩的影响，发现在高Mach数情况下，来流慢声波将直接在边界层内部通过共振机制激发非定常横流涡模态。特别是当边界层内部已经存在饱和定常横流涡的情况下，来流慢声波模态会演化为相应的二次失稳模态。