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测速 (LDV) 测量的实验分析和使用大涡模拟 (LES) 的数值分析，研究了螺旋桨风扇中涡流场的三维结构。研究发现，转子叶尖附近形成了三种涡结构：叶尖涡、前缘分离涡和叶尖泄漏涡。尖端涡流如此强烈，以至于它主导了尖端附近的流场。它的形成从靠近中弦的叶片尖端吸力侧开始。尖端涡流几乎沿切线方向对流，从而冲击相邻叶片的压力表面。涡流结构的非定常性质已由 LES 进行了研究。仿真结果表明，叶尖涡对螺旋桨式风扇涡流的结构和非定常行为起着重要作用。尖端涡流的螺旋型破裂发生在中音附近。破裂引起叶尖涡流的大的周期性运动，使得涡流周期性地冲击相邻叶片的压力表面。涡流结构的运动引起转子叶片和叶片通道内的高压脉动。引入两种类型的螺旋桨式风扇护罩，通过控制风扇转子的叶尖涡来降低风扇噪声。叶尖涡的切向结构在转子叶尖前缘附近引起向内的径向流以及转子叶尖与护罩之间的逆流，对转子内的通流造成较大的阻塞作用。护罩的设计目的是减少转子尖端和护罩之间的逆流，可以减少尖端涡流造成的堵塞效应，从而减慢转子中的流通速度，从而导致风扇噪音的降低。