周向弯曲方向对弯掠叶片小流量工况下气动-声学性能的影响

Effects of Circumferential Bowing Direction on the Aerodynamic and Acoustics Performance of the Bowed & Swept Blade Under Low Flow Rate Conditions

对周向弯曲低压轴流风扇的气动-声学性能进行了数值模拟和试验验证,讨论了不同流量和不同周向弯曲方向对叶栅做功能力、稳定工作范围和叶顶泄漏声源特性的影响规律.结果表明:随着流量减小,周向弯曲使叶栅叶顶区域栅的气流轴向做功能力增强,周向做功能力减弱,叶片负荷减小,周向后弯的效果最明显;周向前弯曲改善了端壁附近的流动状况,是拓宽叶轮的稳定工作范围的重要因素;周向弯曲可增加叶顶泄漏涡的稳定性,减弱叶顶泄漏涡区的Powell声源强度,周向前弯效果最好.叶顶泄漏声源特性随流量变化的规律与宏观声学表现一致.

The numerical simulation and experimental validation were done for the circumferential bowed low pressure axial fan to study its aerodynamic and acoustic performance. The influence law of the flow rates and circumferential bowing directions on the casscade^s work ability, stable working range and ac- coustic source features of tip leakage were discussed. Results show that, by the blade＇s circumferential bowing, the blade＇s loading decreases with the flow rates decreasing, for the axial working ability of the air current increases in the near tip region, and the circumferential working ability decreases, which is the most significant for backward bowed blade. By forward bowing the flow status near the end wall have been improved. It is the important factors to enlarge the stable working range of the impeller. By circumferen- tial bowing the stability of the tip leakage vortex would be inhanced and the strength of Powell acoustic source in the tip leakage vortex area would be decreased, which is the most significant for forward bowed blade. The law of the accoustic source features of tip leakage vs. the flow rate changing is consistent with the representation of micro-acoustic.