Broadband Noise Reduction by Controlling Vortex Structure in Turbomachinery Blade Row

通过控制涡轮机械叶排中的涡结构来降低宽带噪声

基本信息

批准号：
12555049
负责人：
FURUKAWA Masato
金额：
$ 5.06万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12555049/
关键词：
Turbomachinery Blade Row Aerodynamic Noise Vortical Flow Flow Control Noise Reduction

项目摘要

Three-dimensional structure of the vortical flow field in a propeller fan has been investigated by experimental analysis using laser Doppler velocimetry (LDV) measurements and by numerical analysis using a large eddy simulation (LES). It is found that three vortex structures are formed near the rotor tip : the tip vortex, the leading edge separation vortex and the tip leakage vortex. The tip vortex is so strong that it dominates the flow field near the tip. Its formation starts from the blade tip suction side near the midchord. The tip vortex convects nearly in the tangential direction, thus impinging on the pressure surface of the adjacent blade. The unsteady nature of vortex structures has been investigated by LES. The simulation shows that the tip vortex plays a major role in the structure and unsteady behavior of the vortical flow in the propeller fan. The spiral-type breakdown of the tip vortex occurs near the midpitch. The breakdown gives rise to large and cyclic movements of the tip vortex, so that the vortex impinges cyclically on the pressure surface of the adjacent blade. The movements of the vortex structures induce high pressure fluctuations on the rotor blade and in the blade passage.Two types of shroud for propeller fans were introduced to reduce the fan noise by controlling the tip vortex of the fan rotor. The tangential structure of the tip vortex induces an inward radial flow near the leading edge of the rotor tip and a reverse flow between the rotor tip and the shroud, causing a large blockage effect on the through flow in the rotor. The shroud designed so as to diminish the reverse flow between the rotor tip and the shroud can decrease the blockage effect due to the tip vortex, which decelerates the through flow in the rotor, thus leading to the reduction in the fan noise.

通过使用激光多普勒速率（LDV）测量值和使用大型涡流模拟（LES）的数值分析，通过实验分析研究了螺旋桨风扇中涡流流场的三维结构。发现在转子尖端附近形成了三个涡流结构：尖端涡流，前缘分离涡流和尖端泄漏涡流。尖端涡流非常强，以至于它占据了尖端附近的流场。它的构成从Midchord附近的刀片尖端吸入侧开始。尖端涡流几乎沿切向方向对流，从而影响相邻刀片的压力表面。 LES研究了涡流结构的不稳定性质。模拟表明，尖端涡流在螺旋桨风扇中涡流流的结构和不稳定行为中起着重要作用。尖端涡流的螺旋型崩溃发生在中间核心附近。分解产生了尖端涡流的较大和循环运动，因此涡流会在相邻叶片的压力表面周期性地撞击。涡流结构的运动引起了转子叶片和刀片通道上的高压波动。引入了两种用于螺旋桨风扇的罩类型，以通过控制风扇转子的尖端涡流来减少风扇噪声。尖端涡流的切向结构在转子尖端的前缘附近引起向内的径向流，并在转子尖端和裹尸布之间的反向流动，从而对转子中的通过流动产生巨大的阻塞影响。裹尸布设计以减小转子尖端和裹尸布之间的反向流，可以减少由于尖端涡流而引起的阻塞效应，从而减速了转子中的通过流动，从而导致风扇噪声的降低。