Numerical and Experimental Studies of Transition in Three-Dimensional Boundary Layers

为KEB类三维边界层的不稳定性和向湍流过渡的数值（超级计算机）和实验结合研究提供了支持；vonKarman-Ekman-Bodewadt层。特别是，我们强调了自由流扰动的滚动和II型不稳定的激发，这在以前的研究中很少或没有得到关注，以及不同的过渡路线取决于已知在这些层中发生的I型和II型不稳定涡的相对振幅。这些研究应被视为一般性研究，即适用于机械、化学、土木和航空航天工程中出现的各种各样的问题。一个成功的研究项目的结果将为理解在广泛的三维边界层中向湍流的转变提供背景信息。三维边界层出现在后掠翼型上，出现在各种车辆上方和周围的气流中，出现在旋转机械（风扇、泵、涡轮机等）中，出现在旋转抛射体的前端、弯曲管道、河流弯道和行星边界层上。在这些层中向湍流的过渡在工程设计中很重要，因为它影响应力、振动、噪声、升力、传热、烧蚀等。

Support is provided for a combined numerical (super-computer) and experimental study of instability and transition to turbulence in the KEB class of 3-d boundary layers; the vonKarman-Ekman-Bodewadt layers. In particular, we emphasize the roll of free-stream disturbances and the excitation of the Type II instability, which has received little or no attention in previopus studies, and the different routes to transition dependent upon the relative amplitudes of the Type I and Type II unstable vortices that are known to occur in thes layers. These studies should be viewed as generic research, i.e. having application to a wide variety of problems that occur throughout mechanical, chemical, and civil and aerospace engineering. The results of a successful program of research will provide the background information for understanding transition to turbulence in a broad class of 3-d boundary layers. Three-dimensional boundary layers occur over swept-back airfoils, in the flow over and around vehicles of all sorts, in rotating machinery (fans, pumps, turbines, etc.), on the noses of rotating projectiles, incurved pipes, river bends, and planetary boundary layers. Transitition to turbulenace in these layers is important in enginerring design because it affects stresses, vibrations, nois, lift, heat transfer, ablation, etc.