Effect of roughness-induced disturbances on axisymmetric hypersonic laminar boundary layer
Effect of roughness-induced disturbances on axisymmetric hypersonic laminar boundary layer
复制标题
DOI：
10.2514/6.2013-83
复制
发表时间：
2013-01
期刊：
影响因子：
2.2
通讯作者：
D. Estruch-Samper;L. Vanstone;B. Ganapathisubramani;R. Hillier
中科院分区：
文献类型：
--
作者：
D. Estruch-Samper;L. Vanstone;B. Ganapathisubramani;R. Hillier
在炮风洞（M∞=8.9，Re∞/m= 47.4 × 106）中对钝头圆柱体高超声速边界层粗糙度诱导转捩进行了实验研究。短于边界层厚度的离散粗糙度元素被用来诱导传入层流的过渡和不同的测试进行，以获得时间分辨的表面传热测量在横向和轴向下游方向，以及在轴向方向的压力测量。“钻石”和“正方形”平面粗糙度元素被认为是。这些元件被放置在两个不同的轴向位置：在测量位置上游的钝头区域，从而允许长时间的扰动发展，以及在传感器前面的圆柱形区域，以记录元件下游的流动。元素范围从h/d=0.03至0.58被用来研究粗糙度高度的影响。随后研究了扰动流通过由耀斑引起的成熟层流分离区的通道，以评估粗糙度扰动流上的逆压梯度的影响。结果表明，湍流波动的加剧后，它的高度增加的元素。逆压梯度的作用是进一步增强粗糙度引起的扰动的增长。对于淹没在边界层中的粗糙度，平面形状的影响是微不足道的。
An experimental study on roughness-induced transition of a hypersonic boundary-layer over a blunted cylindrical body is conducted in a gun tunnel (M∞=8.9, Re∞/m=47.4x10 6 ). Discrete roughness elements shorter than the boundary layer thickness are used to induce the transition of the incoming laminar flow and different tests are performed to obtain time-resolved surface heat transfer measurements in the transverse and axial directions downstream, as well as pressure measurements in the axial direction. Both ‘diamond’ and ‘square’ planform roughness elements are considered. The elements are placed at two different axial locations: on the blunted nose region far upstream of the measurement location, thus allowing for a long development of disturbances, and on the cylindrical region just ahead of the sensors, to document the flow immediately downstream of the element. Elements ranging from h/d=0.03 to 0.58 are employed to study the effect of roughness height. The passage of the disturbed flow through a well-established laminar separation region induced by a flare is subsequently investigated to assess the effect of adverse pressure gradients on the roughness-disturbed flow. The results suggest an intensification of turbulent fluctuations in the wake of the element as its height is increased. The effect of the adverse pressure gradients is to further enhance the growth of the roughness-induced disturbances. For roughness well submerged in the boundary layer, the effect of planform geometry is found to be insignificant.