The effect of pump impeller modification by a new approach, pump impeller shroud trimming (PIST), on the flow field and pump performance is examined both numerically and experimentally. The primary purpose of this study is to investigate the hydraulic performance of single-phase centrifugal pumps, which are refined by the PIST method, with low and medium specific speeds. In this type of shroud trimming, different trimming sizes are applied only to the shroud plate of the closed impeller, while the geometries (diameters) of the hub and blades remain unchanged. This modification, which increases the clearance between the impeller and casing from the shroud side, causes desirable conditions for pumping fluid containing undissolved gas. Computational fluid dynamics software (ANSYS-CFX) is used to predict the hydraulic performance of centrifugal pumps. Two well-known turbulence models, the renormalization group (RNG) k-ϵ developed model and shear stress transport (SST) k-ω, are used to predict the flow patterns. The computational results are verified through the comparison of experimental and unsteady numerical simulations with steady numerical data. After ensuring the accuracy of the flow-field simulation approach, further numerical analysis is performed for both pumps by changing the impeller shroud diameter. The effects of the geometric changes on the performance curves, efficiency, flow field, pressure distribution inside the pump components and the radial force acting on both pump types are investigated comprehensively. The results show that the shroud trimming reduces the produced head and efficiency at the design points. Examination of the radial force, which is applied on the rotating parts, shows that shroud-trimmed impellers experience higher radial forces than closed impellers in both pump types owing to the lack of a uniform pressure distribution around the impeller outlet. Accordingly, the relevant information obtained is used to modify the existing coefficients to predict the radial forces.

通过数值和实验检验了泵叶轮护罩修整 (PIST) 新方法对泵叶轮的影响对流场和泵性能的影响。本研究的主要目的是研究单相离心泵的水力性能，这些泵通过 PIST 方法改进，具有中低比转速。在这种类型的护罩修整中，不同的修整尺寸仅适用于封闭式叶轮的护罩板，而轮毂和叶片的几何形状（直径）保持不变。这种改进增加了叶轮和外壳与护罩侧之间的间隙，为泵送含有未溶解气体的流体创造了理想的条件。计算流体动力学软件 (ANSYS-CFX) 用于预测离心泵的水力性能。k - ϵ开发模型和剪切应力传递 (SST) k-ω, 用于预测流动模式。通过将实验和非稳态数值模拟与稳态数值数据进行比较，验证了计算结果。在确保流场模拟方法的准确性后，通过改变叶轮护罩直径对两台泵进行进一步的数值分析。全面研究了几何变化对性能曲线、效率、流场、泵组件内部压力分布以及作用在两种泵上的径向力的影响。结果表明，护罩修整降低了设计点的产生水头和效率。检查施加在旋转部件上的径向力，表明，由于叶轮出口周围压力分布不均匀，在两种泵类型中，护罩修剪叶轮比封闭叶轮承受更高的径向力。因此，获得的相关信息用于修改现有系数以预测径向力。