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Unsteady Behavior of a Tip Vortex and Its Effect on the Unsteady Aerodynamic Force of a Downstream Blade

叶尖涡的非定常行为及其对下游叶片非定常气动力的影响

基本信息

批准号：
06651065
负责人：
WATANABE Toshinori
金额：
$ 1.47万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06651065/
关键词：
Turbomachinery Cascade Flow Unsteady Internal Flow Tip Clearance Tip Leakage Flow Tip Vortex Unsteady Aerodynamic Force ターボ機械翼列干渉振動翼列

项目摘要

Unsteady behavior of a tip leakage vortex affected by periodic gust, and the one generated from an oscillating blade, were experimentally studied with a three-sensor hot-wire anemometer.The experiment was conducted in a low-speed wind tunnel in which a blade was set with a clearance between its tip and the tunnel wall.The periodic gust from rotating cylinders was introduced to the blade, and the three dimensional flow velocities were measured at downstream positions.When the wake reached the blade leading edge, the tip vortex was observed to diminish, and then it gradually regained the vorticity.The vortex center was found to oscillate with a large amplitude in the direction of blade thickness.It was thus clarified that the tip vortex was quite strongly affected by the incoming gust.The tip vortex generated from an oscillating blade was then detected by the hot-wire anemometry.The in-phase oscillation of the tip vortex with the blade oscillation was clearly observed.The change in the phase of the vortex oscillation in the downstream direction could be explained by the convection of the vortex due to mean flow.In the final stage, the unsteady pressure distributions were measured on a flat plate set at a downstream position of the oscillating blade, The surface pressure substantially decreased due to the passage of the oscillating tip vortex, and, thereby, the unsteady aerodynamic force on the flat plate was significantly changed.When the tip vortex moved across the flat plate, its position changed widely in the spanwise direction.The unsteady pressure field was accordingly changed in a wide area in the spanwise direction.A theoretical study was performed at the same time, in which a new singularity method was developed to estimate the induced unsteady aerodynamic force by the unsteady tip vortex with arbitrary vorticity and position.

利用三传感器热线风速仪对周期性阵风和叶片振荡产生的叶尖泄漏涡的非定常特性进行了实验研究。实验在低速风洞中进行，在风洞中设置叶片，叶片尖端与风洞壁之间有间隙。将旋转气缸的周期性阵风引入叶片，并在下游位置测量了三维流速。当尾流到达叶片前缘时，叶尖涡逐渐减小，然后逐渐恢复涡度。旋涡中心沿叶片厚度方向振荡幅度较大。由此可见，顶涡受到来风的强烈影响。然后用热线风速仪检测由振荡叶片产生的叶尖涡。观察到叶尖涡与叶片的同相振荡。涡旋振荡在下游方向的相位变化可以用平均流量引起的涡旋对流来解释。在最后阶段，在振荡叶片下游位置的平板上测量非定常压力分布，由于振荡叶尖涡的通过，表面压力大幅降低，从而使平板上的非定常气动力发生了明显变化。当叶顶涡在平面上移动时，其位置在展向上发生了较大的变化。非定常压力场在展向上发生了较大范围的变化。同时进行了理论研究，提出了一种新的奇异性方法来估计任意涡度和位置的非定常叶尖涡诱导的非定常气动力。