Department of Fluid Mechanics and Heat Transfer, University of Technology Vienna, Resselgasse 3, 1040 Vienna, Austria
HOERBIGER Ventilwerke GmbH & Co. KG, Braunhubergasse 23, 1110 Vienna, Austria.
Philos Trans A Math Phys Eng Sci. 2014 Jul 28;372(2020). doi: 10.1098/rsta.2013.0346.
In this work, laminar transonic weakly three-dimensional flows at high Reynolds numbers in slender channels, as found in microsupersonic nozzles and turbomachines of micro-electro-mechanical systems, are considered. The channel height is taken so small that the viscous wall layers forming at the channel walls start to interact strongly rather than weakly with the inviscid core flow and, therefore, the classical boundary layer approach fails. The resulting viscous-inviscid interaction problem is formulated using matched asymptotic expansions and found to be governed by a triple-deck structure. As a consequence, the properties of the predominantly inviscid core region and the viscous wall layers have to be calculated simultaneously in the interaction region. Weakly three-dimensional effects caused by surface roughness, upstream propagating flow perturbations, boundary layer separation as well as bifurcating solutions are discussed. Representative results for subsonic as well as supersonic conditions are presented, and the importance of these flow phenomena in technical applications as, for example, a means to reduce shock losses through the use of deformed geometry is addressed.
在这项工作中，考虑了在高雷诺数下，微超声速喷管和微机电系统涡轮机械中存在的细长通道中的层流跨音速弱三维流动。通道高度取得很小，以至于在通道壁上形成的粘性壁层开始与无粘核心流强烈而不是弱相互作用，因此经典的边界层方法失效。使用匹配渐近展开法对由此产生的粘性-无粘相互作用问题进行了公式化，并发现它由一个三层结构控制。因此，在相互作用区域中必须同时计算主要无粘性核心区域和粘性壁层的特性。讨论了表面粗糙度、上游传播流动扰动、边界层分离以及分叉解引起的弱三维效应。给出了亚声速和超声速条件下的代表性结果，并讨论了这些流动现象在技术应用中的重要性，例如通过使用变形几何来减少冲击波损失的手段。
