变螺距叶片对螺旋离心泵轴向力的影响

Influences of Variable-pitch Blade on the Screw Centrifugal Pump Axial Force

采用150×100LN-32型螺旋离心泵的结构尺寸,根据螺旋离心泵的叶片变螺距型线方程设计出8种螺距变化方式不同的螺旋离心泵。以这8种不同螺距的螺旋离心泵为对象,选用清水和沙水固液两相流为介质,基于FLUENT软件,建立相对坐标系下的时均连续方程及N-S方程,并采用标准k-ε方程湍流模型、非结构四面体网格和SIMPLE算法进行数值模拟,得到螺旋离心泵的压力分布后计算出不同螺距下的轴向力。在此基础上,将等螺距的螺旋离心泵计算的进出口压力差和试验测量值进行对比,间接地验证了利用数值模拟计算轴向力的准确性。研究不同螺距下的不同流量、不同体积分数和介质为清水时不同螺距下的轴向力变化趋势和规律,通过数据分析,可知螺旋离心泵轴向力的大小受多种因素的影响,而叶轮的螺距变化改变着内流场的变化,对螺旋离心泵轴向力的大小起着决定性作用,轴向力随着螺距变化的曲线呈现出一定的凹凸性。针对不同参数,合理地设计叶片螺距,对于提高螺旋离心泵的可靠性和稳定性具有重要意义。

Using the structure and size of type 150×100LN-32 centrifugal pump,according to the vane profile parameter equation group for variable-pitch screw centrifugal pump,eight screw centrifugal pumps with variable screw pitch are designed.By taking eight screw centrifugal pumps with different pitch as the object and selecting solid-liquid two-phase flow of clear water and sandy water as the medium,the time-averaged continuity equation with relative coordinates and the N-S equation are established on the basis of FLUENT software.And standard k-ε equation turbulence model,unstructured tetrahedral mesh and SIMPLE algorithm are used to carry out numerical simulation,and then axial force with different pitch is calculated after obtaining the pressure distribution of the screw centrifugal pump.Based on this,comparison is made between the experimental measurement value and the calculated pressure difference between import and export of the screw centrifugal pump with equal pitch,thus indirectly verifying the accuracy of making use of numerical simulation to calculate the axial force.The change trend and rule of the axial force under different pitch with different flow,different volume fraction and with clear water as medium are researched.Through data analysis,it can be seen that the size of the axial force of screw centrifugal pump is affected by many factors,but variable pitch of the impeller alters internal flow field,it plays a decisive role in the size of the axial force of screw centrifugal pump,the axial force shows a certain degree of convexity with the curve of the pitch changing.For different parameters,reasonably designing the blade pitch has important significance to improving the reliability and stability of screw centrifugal pump.