单动叶安装角异常时轴流风机的噪声特性

Acoustic Characteristics of an Axial Flow Fan With Abnormal Installation Angle of Single Blade

以OB-84型单级动叶可调轴流风机为研究对象,在大涡模拟基础上,引入FW-H声学模型,模拟得到了安装角异常时风机声源强度分布和不同区域的气动噪声时频特性,并与正常工况进行了比较。研究表明:该风机的主要噪声源集中在吸力面叶片的前缘及叶顶附近;当动叶安装角异常时,高强度噪声源范围扩大,声功率级和声压级均有不同程度提高,致使在异常叶片周边流道内形成高噪声带;声压脉动区间和声压幅值受动叶偏离度影响较大,且越靠近声源的区域受影响程度愈显著;动叶安装角异常增强了动叶区宽频噪声特性,分散了其他区域在低频段的离散峰值,使其向高频段转移,而位于中高频段的宽频噪声明显提高。

Taking a variable pitch axial fan of OB-84 type as an example, the distribution of sound source intensity and characteristics of monitoring regions in time and frequency domains were simulated using the large eddy simulation （LES） and FW-H noise model, and the results of abnormal installation angles were compared with those under normal condition. Simulated investigations show that main noise sources of the fan are located at the blade leading edge and tip of suction surface; the range of intensive noise source enlarges with increasing abnormal installation angle. Additionally, the acoustic power level and sound pressure level ascend to some extent, thus the higher noise band is developed around the passages of abnormal blade. Deviation degree of abnormal installation angle has a significant effect on the range and amplitude of sound pressure, and the closer it gets to the noise source, the higher effect it could have. The broadband noise of blade region is enhanced under abnormal installation angle, and the discrete peak of aerodynamic noise transits from low-frequency region to high-frequency region, while the increase of broadband noise in middle-high frequency region is visible distinctly.