A diffuser acts as an energy conversion device to improve the performance of a submersible pump. The blade inlet angle of a diffuser is the most important geometric parameter that affects the performance of a submersible pump. The present paper focused on the effects of different blade inlet angles of a diffuser on the performance of a submersible pump. Firstly, the theoretical analysis of the diffuser characteristic curve was carried out; Secondly, five sets of submersible pump models with different blade inlet angles and the same impeller were built and simulated. Finally, based on the obtained results, two characteristic parameters reflecting inlet and outlet velocity distributions in the diffuser were introduced, and the quantitative relationship between internal and external characteristics of the diffuser was established. It was found that as the blade inlet angle of the diffuser increased, the optimum operating point moved in the direction of large flow rate. When the blade inlet angle of the diffuser was in the range of 27°–30°, the efficiency of the submersible pump reached more than 75%, and the maximum change in the corresponding working flow was 0.2 times of the theoretical discharge. Furthermore, the values of the maximum speed reduction ratio ( K 2 , that is the ratio of inlet circumferential flow velocity to minimum flow velocity on the intermediate flow surface of a diffuser.) were located near 1.6, and they were positioned ( X min , that is the relative position of the lowest flow velocity on the intermediate flow surface along the flow path of the diffuser.) near the midpoint of the flow path of the diffuser. Moreover, with the increase in the change rate of different blade inlet angles ( α ′ 3 n ), the high-efficiency interval breadth ( W , that is the relative rate of change in flow rate with respect to the highest flow rate at η ≥ 75 % .) manifested an increasing trend. When α ′ 3 n exceeded 0.06, the value of W increased significantly, and the range of applicable flow intervals expanded simultaneously. According to performance requirements, the distribution of the internal flow field was specified to further enhance the adaptability of the submersible pump to different working conditions.

中文翻译：

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扩压器叶片入口角对潜水泵性能的影响

扩散器作为能量转换装置来提高潜水泵的性能。扩压器的叶片入口角是影响潜水泵性能的最重要的几何参数。本文重点研究了扩压器不同叶片入口角度对潜水泵性能的影响。首先对扩散器特性曲线进行了理论分析；其次，建立并仿真了五套不同叶片入口角和相同叶轮的潜水泵模型。最后，在得到的结果的基础上，引入了反映扩压器入口和出口速度分布的两个特征参数，建立了扩压器内外特性的定量关系。结果表明，随着扩压器叶片进口角的增大，最佳工作点向大流量方向移动。当扩压器叶片入口角在27°～30°范围内时，潜水泵的效率达到75%以上，相应工作流量的最大变化为理论流量的0.2倍。此外，最大减速比（K 2 ，即扩散器中间流面上的入口圆周流速与最小流速之比）的值位于1.6附近，并且它们位于（ X min ，即最低流速在沿扩散器流动路径的中间流动表面上的相对位置。）靠近扩散器流动路径的中点。而且，随着不同叶片入口角（α′3n）变化率的增加，高效区间宽度（W，即η≥75%时流量相对于最高流量的相对变化率.) 呈上升趋势。当α′ 3 n 超过0.06时，W值显着增加，同时适用流段范围扩大。根据性能要求，规定了内部流场的分布，进一步增强了潜水泵对不同工况的适应性。W 值显着增加，同时适用的流动区间范围扩大。根据性能要求，规定了内部流场的分布，进一步增强了潜水泵对不同工况的适应性。W 值显着增加，同时适用的流动区间范围扩大。根据性能要求，规定了内部流场的分布，进一步增强了潜水泵对不同工况的适应性。