出口轮毂形状对大型轴流风机性能影响的数值研究

Numerical investigation of effect of outlet hub geometry on performance of large scale axial fan

针对某大型轴流风机设计了4种出口段轮毂匹配方案,采用数值模拟方法对比分析了4种方案下的风机特性和叶尖以及叶根流场结构.结果表明:出口轮毂形状的变化对该风机叶尖流场结构影响很小;该风机出口无轮毂时,在叶根区域出现约占20%叶高区域的分离流,损失严重,降低了工作效率;在相同的叶尖间隙下,风机效率随着出口轮毂扩压角的减小而提高;在风机出口增加一个匹配的平直轮毂或收缩轮毂可使叶根分离涡后移,分离区域减小至5%叶高以下,同时可使该风机效率至少提高2个百分点.

Four different outlet hub geometries of a large scale axial fan were designed and investigated.CFD methods were used to compare the fan characteristics and analyze the flow field structures in the blade tip and blade root.The results show that variation of outlet hub geometry has little effect on the fan＇s tip flow structure;there is a large separated flow in the blade root region which occupies 20%of blade height when the fan isn＇t provided with outlet hub,causing serious loss and decrease of efficiency;with the same blade tip clearance,the fan＇s efficiency increases when the outlet hub diffuser angle decreases;a matching straight or convergent hub could make the blade root separated vortex move backwards,reduce the separated area to 5% of blade height and increase at least 2percentage points of the fan efficiency.