对转轴流泵的设计与数值分析

对转轴流泵是由2个叶轮串联在一起,以相反的方向绕同一轴心旋转的轴流泵。与常规前、后导叶式轴流泵相比,在同样设计参数条件下,对转式轴流泵具有相对体积小、运转速度低、抗空化性能好和推重比高等特点。为探究对转轴流泵的设计理论和方法,设计了一对转轴流泵的前、后置叶轮,应用Matlab软件实现参数化设计,搭建了自动分析优化平台,实现了对转轴流泵从设计参数输入到三维优化模型的自动输出。在此基础上,分析了前、后叶轮的载荷分配比例、轴向间隙和后置叶轮不同转速对轴流泵性能的影响。结果表明:后置叶轮的效率和扬程一般低于前置叶轮,可以通过载荷的重新分配,降低后置叶轮的转速来提高轴流泵的总体效率;轴向间隙存在最优值,建议设定为前置叶轮弦长的5%左右;后置叶轮转速的合理选择,能够减弱或消除常规轴流泵在小流量工况扬程曲线出现的“驼峰”现象,从而拓宽了轴流泵运行工况范围。

Design and numerical analysis of the counter-rotating axial flow pump

The counter-rotating axial flow pump is an axial flow pump with two impellers connected in series and rotating around the same axis in the opposite direction.Compared with the conventional front or rear guide vane axial flow pump under the same design parameters,the counter-rotating axial flow pump has the characteristics of relatively small size,low operating speed,good cavitation suppression and high thrust-weight ratio.In order to explore the design theory and method of counter-rotating axial flow pump,the front and rear impellers for counter-rotating axial flow pump were designed.The software MATLAB was chosen as the platform to realize parameterized design,the automatic analysis and optimization platform was established,which realizes input of design parameters of the counter-rotating axial flow pump and output of three-dimensional optimization model.Based on this,the effects of load distribution ratio between the front and rear impellers,the axial clearance and the different speeds of the rear impellers on performance of the axial flow pump were analyzed.The results show that the efficiency and head of the rear impeller are generally lower than those of the front impeller.The overall efficiency of the axial flow pump can be improved by redistributing the load and reducing the speed of the rear impeller.There is an optimal value for axial clearance.It is recommended to set it to about 5%of the front impeller chord length.The reasonable selection of speed of the rear impeller can reduce or eliminate the hump phenomenon on the head curve of conventional axial flow pump under small flowrate conditions,which has the potential to expand the operation range of the axial flow pump.