变工况下周向弯曲风扇叶顶涡声特性

Research of Aerodynamic Noise Source in Tip Region of Axial Fans with Circumferential Skewed Blades at Off-Design Conditions

采用计算流体力学数值方法研究变工况下周向弯曲低压轴流风扇的叶顶泄漏流动特性,结合涡声理论分析泄漏涡与声源的协同特性,分析叶片不同周向弯曲方向对协同性的影响,并通过近场机匣壁面动态压力测量和远场声学测量,验证叶片周向弯曲方向对近远场声学特性的控制规律.研究表明,泄漏涡声源是周向弯曲叶轮小流量工况下的重要声源,速度矢量与涡矢量的夹角值控制叶顶区域声源强度和分布.近远场实验结果表明,泄漏涡声源与远场声学关系密切.

Aerodynamic noise source generated by tip leakage flow in circumferential skewed axial fans was studied by CFD simulation and experiments under off-design conditions.Relationship between tip leakage flow and aerodynamic noise was analyzed based on vortex-sound theory of low speed homentropic flow.Synergy between acoustic source and tip leakage vortex was discussed.Pressure test on casing wall and acoustic far field test were conducted to find how the different circumferential skewed direction control acoustic characteristics.The results show that the acoustic source generated by tip leakage vortex of circumferential skewed blades is an important noise source under off-design conditions.The angle between velocity vector and vortex vector controls the strength and the distribution of the acoustic source in tip clearance region.The acoustic source in tip clearance region is related with the acoustic far field under off-design conditions.