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提出了用正反问题迭代法设计混流泵叶轮的新方法。该方法能够有效地弥补传统方法设计叶片时轴面流动的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场计算的影响。通过两类相对流面迭代求解流体连续方程与运动方程,完成设计叶轮的正问题计算。采用逐点积分法进行叶片骨线绘型,在轴面上加厚叶片,在保角变换平面内修圆叶片头尾部,完成反问题设计。正反问题迭代计算直至收敛,最终完成混流泵叶轮的设计。采用SIMPLEC算法,通过求解Navier-Stokes方程和RNGk-ε湍流模型方程,模拟了混流泵叶轮内的三维流场,获得了叶轮内的速度与压力分布。结果表明:正反问题迭代方法设计的叶片对于水流的控制能力增强,叶轮内部流动稳定,压力分布均匀,具有更优的水力性能。
A new method of designing Francis pump impeller by the iterative method of forward and backward problems is proposed. The method can effectively make up for the defect that the calculation of the axial flow only satisfies the fluid continuous equation when the blade is designed according to the traditional method, and simultaneously considers the influence of the shape of the blade on the calculation of the axial flow field. Through two kinds of relative flow surface iterative solution of fluid continuous equations and equations of motion, to complete the design of the impeller is a positive problem calculation. Point-by-point integral method is used to draw the blade bone line, thicken the blade on the axial surface and round the blade tail in the conformal transformation plane to complete the inverse problem design. The positive and negative problems are iteratively calculated until convergence, and finally the design of Francis pump impeller is completed. The SIMPLEC algorithm was used to simulate the three-dimensional flow field in the impeller of the Francis turbine by solving Navier-Stokes equations and RNGk-ε turbulence model equations. The velocity and pressure distribution in the impeller were obtained. The results show that the blades designed by the iterative method of forward and reverse problems can enhance the control of water flow, stabilize the flow inside the impeller, distribute the pressure evenly and have better hydraulic performance.