Micro-ramp control for oblique shock wave / boundary layer interactions
Micro-ramp control for oblique shock wave / boundary layer interactions
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DOI：
10.2514/6.2007-4115
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发表时间：
2007-06
期刊：
影响因子：
--
通讯作者：
C. Ford;H. Babinsky
中科院分区：
文献类型：
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作者：
C. Ford;H. Babinsky
超音速发动机的进气口以激波/边界层相互作用（SBLIs）为特征，通常采用边界层放气控制。排气流的动量损失导致高阻力，影响进气性能。微斜坡亚边界层涡发生器（SBVGs）被提出作为斜斜亚边界层流动控制的一种替代形式，以降低排放要求。实验以2.5马赫的速度进行，以表征这种装置上的流动细节，并研究它们控制斜激波与隧道底板上自然形成的湍流边界层之间相互作用的能力。测试了四种尺寸的微坡道，高度范围为非受控边界层厚度的25%至75%。所有尺寸的微泵上的流动都是相似的，其特征是流向的反旋转涡携带高动量流体，局部减少了边界层位移厚度。当安装在冲击相互作用之前时，发现微坡道的定位是有限的。微坡道并没有消除流动分离。然而，先前的二维分离被分解成周期性的三维分离区。相互作用长度减小，相互作用两端的压力梯度增大。
Supersonic engine intakes operating supercritically feature shock wave / boundary layer interactions (SBLIs), which are conventionally controlled using boundary layer bleed. The momentum loss of bleed flow causes high drag, compromising intake performance. Micro-ramp sub-boundary layer vortex generators (SBVGs) have been proposed as an alternative form of flow control for oblique SBLIs in order to reduce the bleed requirement. Experiments have been conducted at Mach 2.5 to characterise the flow details on such devices and investigate their ability to control the interaction between an oblique shock wave and the naturally grown turbulent boundary layer on the tunnel floor. Micro-ramps of four sizes with heights ranging from 25% to 75% of the uncontrolled boundary layer thickness were tested. The flow over all sizes of microramp was found to be similar, featuring streamwise counter-rotating vortices which entrain high momentum fluid, locally reducing the boundary layer displacement thickness. When installed ahead of the shock interaction it was found that the positioning of the micro-ramps is of limited importance. Micro-ramps did not eliminate flow separation. However, the previously two-dimensional separation was broken up into periodic three-dimensional separation zones. The interaction length was reduced and the pressure gradient across the interaction was increased.