A novel passive control technique for laminar flow over air transportation vehicles and space reentry vehicles flying at high supersonic and hypersonic speeds is disclosed. The control of laminar flow can be achieved by applying an array of surface roughness elements in the region before the laminar-turbulent transition. For example, an array of two-dimensional rings, stripes, or closely packed three-dimensional isolated roughness elements may be used to stabilize the instability waves and delay transition. The roughness elements may have a height between 40% and 60% of the local boundary-layer thickness. The exact location, height, and spacing of surface roughness elements may be determined by a numerical simulation strategy based on the most unstable second mode, e.g. using known eN transition prediction method, experimental measurement, or any other suitable technique.
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机译：公开了一种新颖的被动控制技术，其用于在高超声速和高超声速飞行的空中运输车辆和空间再入飞行器上的层流。层流的控制可通过在层流湍流过渡之前的区域中应用一系列表面粗糙度元素来实现。例如，可以使用二维环，条纹或紧密堆积的三维隔离粗糙度元素的阵列来稳定不稳定波并延迟过渡。粗糙度元件的高度可以在局部边界层厚度的40％至60％之间。表面粗糙度元件的确切位置，高度和间距可以通过基于最不稳定的第二模式（例如第二模式）的数值模拟策略来确定。使用已知的e N 过渡预测方法，实验测量或任何其他合适的技术。
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