扩压器前缘开槽结构对离心鼓风机性能及流场压力脉动的影响

Effects of Slotted Structure at Leading Edge of Diffuser on Performance and Unsteady Pressure in a Centrifugal Blower

为提高离心鼓风机的气动性能,对一离心鼓风机扩压器叶片前缘前后盖板同时进行开槽处理,并采用数值模拟方法定量研究开槽结构对离心鼓风机气动性能及内部流场的影响。结果表明,具有开槽结构的扩压器进口回流与上游叶轮尾迹影响明显减小,其次一部分高速流体从开槽区域射入扩压器吸力面侧,并与主流掺混,从而加速了扩压器流道中后段的流动,抑制了叶片尾部的附面层分离。因此,在适宜的开槽参数下,开槽结构能提高离心鼓风机的总压升和效率。离心叶轮出口和叶片扩压器进口典型位置非定常压力脉动频域特性的结果表明:在开槽扩压器内部叶频的影响减小,而轴频起了主导作用,并发现开槽处理后,扩压器内部的压力脉动幅值明显减小,减小压力脉动的幅值在一定程度上能减弱离心鼓风机内的流动诱导噪声。

In order to improve the aerodynamic performance of the centrifugal blower,the slot treatment was performed on the hub side and shroud side at leading edge of diffusers of a centrifugal blower,and the influence of the slot parameters on the aerodynamic performance and the internal flow field of the centrifugal blower was analyzed by using the numerical simulation method. The results showed that the impact of reflux and wake decreases evidently in the diffuser inlet with the slot treatment. In addition,a portion of the high speed fluid is injected into the suction side of diffuser from the slot region and blends with the mainstream,thus accelerating the flow of the diffuser at middle and rear section and suppressing the flow separation in the trailing edge of blade. Therefore the slot structure can improve the total pressure rise and the efficiency of the centrifugal blower under the optimum conditions. Frequency domain characteristics of the unsteady pressure fluctuations at the impeller outlet and vane diffuser inlet showed that the influence of the blade frequency is small,and the axial frequency is dominant. It was found that the pressure fluctuation amplitude inside diffuser is significantly decreased after the slot treatment,weakening the flow- induced noise inside the centrifugal blower.