混流泵叶轮设计正反问题迭代方法

Iteration method of direct inverse problem of mixed-flow pump impeller design

基于两类相对流面流动理论,通过迭代计算求解流体的连续方程与运动方程,得到混流泵叶轮内的轴面流场,实现了正问题计算.基于轴面速度分布规律,采用逐点积分法完成叶片骨线绘型,并在轴面内进行叶片加厚,在保角变换平面内对叶片头部和尾部进行修圆,完成了反问题设计.以此为基础,将正问题与反问题相结合,提出了混流泵叶轮正反问题迭代设计方法.在该设计方法中,正问题计算为反问题设计提供流场信息,反问题设计则为正问题计算提供叶轮模型,正反问题反复迭代直到收敛,最终完成叶轮的设计.结果表明:根据正反问题迭代方法设计得到的叶轮载荷分布均匀,水力效率高.该方法弥补了传统方法设计叶片时轴面流动计算仅满足流体连续方程的缺陷,同时考虑了叶片形状对轴面流动计算的影响,最终设计得到的叶片型线同时满足流体连续方程和运动方程,该方法提高了叶轮设计计算的精度,为进一步开展混流泵叶轮的优化设计研究提供了重要的平台.

The meridional flow field inside a mixed-flow pump was obtained by employing iterative calculation to settle the continuity and motion equations of fluid,based on the flow theory of two families of relative stream surfaces.Thus,the direct problem calculation was achieved.The inverse problem of mixed-flow pump was solved by firstly employing point-by-point integration method to draw the blade shape,secondly thickening the blade on the meridional surface and finally smoothing the leading edge of the blade by conformal mapping.On the base of this,the iterative design method of direct and inverse problems of the mixed-flow pump impeller was developed by combining the direct problem with the inverse problem.In this design method,the direct problem calculation offered the flow field information to the inverse problem design and the inverse problem design provided the impeller model to the direct problem calculation.The impeller was not finally determined until the direct and inverse problems converged.The results showed that the impeller,obtained by iterative design method of direct and inverse problems,has more uniform load distribution and higher hydraulic efficiency.This iterative design method can effectively cover the shortage of the traditional method,which is that the meridional flow calculation can only satisfy the continuity equation of fluid when designing the blade.In addition,this method can also consider the effect of blade shape on the meridional flow calculation.Therefore,the finally determined blade shape,obtained in the condition of satisfying both the continuity and motion equations of fluid,can not only enhance the accuracy of design calculation,but also provide a platform for further research of optimization design of the mixed-flow pump impeller.