超低比转速离心风机无叶扩压器改进设计研究

Study on Improved Design of Vaneless Diffuser for Centrifugal Fan with Ultra-low Specific Speed

为了提高超低比转速离心通风机的气动性能,通过理论分析提出了降低超低比转速离心风机内部损失的扩压器设计方法,采用数值模拟的方法得到不同直径旋转扩压器和静止扩压器的性能特点,从风机静压、效率、扩压器静压恢复系数和滞止压力损失系数等方面对其分析比较。研究得到:在设计流量下,旋转扩压器直径增大8.7%后,风机静压提升6.8%,效率提高3%,扩压器静压恢复系数提高62.9%,扩压器内滞止压力损失减少71.9%,表明在尺寸允许范围内适当增大扩压器直径可获得更高的静压升,同时降低损失、提高效率;另外,静止扩压器壁面与通流之间的剪切力更大,损失更多,设计流量下静止扩压器比等直径旋转扩压器滞止压力损失增加75.2%,表明旋转扩压器比静止扩压器有更好的性能。

In order to improve the aerodynamic performance of ultra-low specific speed centrifugal fan,the design method of diffuser to reduce the internal loss of the fan was proposed by theoretical analysis.The performance characteristics of rotating diffuser and static diffuser with different diameters were obtained by numerical simulation.The static pressure,efficiency,static pressure recovery coefficient and stagnation pressure loss coefficient of the diffusers were analyzed and compared.The results show that when the diameter of the rotating diffuser is increased by 8.7%,the static pressure of the fan is increased by 6.8%,the efficiency is increased by 3%,the static pressure recovery coefficient of the diffuser is increased by 62.9%,and the stagnation pressure loss in the diffuser is decreased by 71.9%at the design flow rate,indicating that within the allowable size range,increasing the diameter of the diffuser appropriately can obtain higher static pressure rise,reduce the loss and improve the efficiency.In addition,the shear force between the wall of the static diffuser and the flow is larger and the loss is more.At the design flow rate,the stagnation pressure loss of the static diffuser is 75.2%higher than that of the equal diameter rotating diffuser,indicating that the rotating diffuser has better performance than the static diffuser.