轴流风机叶片展向结构变化对性能影响的数值分析

基于电站风机裕量普遍较高的现象,本文以OB-84轴流风机为对象,采用Fluent模拟了叶顶切割和轮毂加粗后的风机性能,分析了2种改造方式对风机性能、内流特征及轴功率的影响。结果表明:体积流量qv≥33 m3/s时,叶轮改造后的全压和效率均随叶高减小而降低,但轮毂加粗后的风机性能优于叶顶切割情形;qv<33 m3/s时,2种改造方式均可使不稳定区变缓甚至消失;叶轮改造后动叶总压升系数小于原风机,但导叶扩压能力增强,且叶轮改造能改善中小流量下风机噪声特性;叶顶切割后,轴功率均小于原风机;在高于设计流量下,与原风机相比,轮毂加粗后的轴功率呈减小趋势,但叶顶切割方式的降幅更大。

Numerical Analysis on the Effect of Varied Blade Spanwise Structure on an Axial Flow Fan Performance

Based on the high margin of power plant fan,an axial flow fan is taken as an example to analyze the effect of blade trimming and increasing hub diameter on performance,internal dynamics and shaft power,which is simulated by Fluent. The results show that both full pressure and efficiency reduce with decreasing blade height when volume flow rate is over 33 m3/ s,but fan performance under increasing hub diameter is better than that of blade trimming. When flow rate is less than 33 m3/ s,two innovation methods can alleviate or eliminate unstable region. The total pressure rise with impeller reform is less than that of the original fan,but the diffusion ability of guide vane is enhanced. And impeller reform can improve noise characteristics under medium and small flow rate. Shaft power after blade trimming is less than that of the original fan. When flow rate is more than the design condition,the shaft power after increasing hub diameter decreases which is comparing with the original fan,but the descent of blade trimming is greater.