集流器偏心对前弯离心风机气动性能影响分析

Study on the Effect of Inlet Nozzle Installation on Performance of Forward-Curved Blades Centrifugal Fan

前弯离心风机叶片长、弯度大,蜗壳非对称性加剧其与叶轮干涉作用。为研究流动非对称性对前弯离心风机气动性能影响,本文对某前弯离心风机进行集流器偏心安装,采用数值模拟对风机三维不可压缩流场进行求解,预测不同安装角及偏心距下的离心风机性能。通过观察分离流动与气流角分布情况,给出偏心角、偏心距改变对叶片入口流动分离影响细节。结果显示当偏心距L=3 mm,偏心角θ=120℃时分离现象明显减少,分离干涉得到改善,结合试验对偏心方案进行可行性验证,采用该分析方法可为预测非对称入流条件下的离心风机内部流动特征提供一种途径。

The forward-curved （FC） blades centrifugal fan feature long vanes and big blade curvature. Influenced by asymmetric of volute structure, the unsteady flow impact on the impeller is intensified. In order to study the flow asymmetry influence, an aerodynamic investigation on the FC blades centrifugal fan is carried out in this paper. Firstly, observing flow separation and flow angle distribution in the impeller region, three-dimensional flow phenomenon of non-uniform fluid flow is discussed. Secondly, the installation location of inlet nozzle is adjusted based on the analysis results, and the centrifugal fan with eccentric inlet nozzle is proposed. Prom the analysis results, L = 3 mm, 0 = 120° of the eccentric inlet nozzle could help improve internal flow of the fan and reduce the flow separation. Finally＇, the comparison of aerodynamic performance tests show the total pressure and the efficiency of the new fan are improved, which are in good agreement with the prediction of simulation results. This method is beneficial to study the internal flow characteristics of centrifugal fan in the condition of the asymmetric inflow.