基于测试线法的风轮近尾迹辐射噪声研究

ACOUSTIC RADIATION TEST FOR NEAR WAKE OF ROTOR BASED ON TEST LINES

在风洞开口实验段,针对不同尖速比应用BSWA VS302USB振动噪声采集分析系统对水平轴风力机叶尖下游4个角度的测试线进行噪声测试。叶尖辐射声中的主要成分是叶片的旋转谐波声,其向风轮下游传播的过程中迅速衰减。在各测试线上,随着测点向风轮下游移动,叶轮辐射声迅速衰减,并在一定距离之后低于背景声,尖速比越高,风轮下游辐射声衰减到背景声级的位置距离风轮越远。风轮旋转过程中,在叶尖后方形成高压力脉动的区域,随着尖速比增加,该区域增大,在向下游扩展的同时影响范围扩大。叶尖区域压力脉动向下游传播的过程中先迅速降低,在一定距离后低于风洞来流的压力脉动,并在更远的下游又高于风洞来流的压力脉动。

In wind tunnel opening, the noise in four test lines was measured by BSWA VS302USB Noise and Vibration Analysis System under different tip speed ratio. The main component of blade tip acoustic radiation is the rotated harmonic sound; it decayed rapidly in the process of spreading to the downstream. In the each test line, with the measuring points moving to the downstream, the acoustic radiation of the wind rotor decayed rapidly, after a certain distances, it is lower than the background noise. The higher is the tip speed ratio, the farther is the distance which is the acoustic radiation decayed to the background sound. There is a high-pressure pulse region in the tip rear, which formed by rotating of the wind rotor. With the increasing of the tip speed ratio, the region increased. With the expanding to the downstream, the infiuent ranges expanded. In the process of the pressure fluctuation of tip region transmitting to the downstream, it declined rapidly at first, after a certain distance, it is lower than the pressure fluctuation of the wind tunnel outflow, and in the farther downstream, higher than it.