To make up for the lack of study on high-speed water jet propulsion pump tip clearances, a newly developed water jet pump system close to the critical specific speed nsc has been investigated. Based on the body of the underwater vehicle and the non-uniform flow, the pump system with different tip clearance sizes (0.1, 0.2, 0.4, 0.8 mm) is evaluated and validated via numerical simulations. Preliminary steady simulating results demonstrate that increasing the tip clearance size can reduce the overall performance of the head, the efficiency, pump thrust, and the consuming power. Following further unsteady simulations, we reveal the unsteady dynamic performance induced by the tip clearances, related to the similar distribution characteristics of the pressure intensities and the pressure pulsations around the underwater vehicle. Furthermore, the pressure intensity and pressure pulsations in the pump increase with the tip clearance. Quantitative and comparative analysis of the distribution characteristics indicates that the blade loading and scrapping effect of the shroud are key factors influencing the leakage flow. At last, the leakage flow's dynamic distributing law under different tip clearances have been clarified.

为弥补高速喷水推进泵叶尖间隙研究的不足，新开发的接近临界比转速的喷水泵系统nsc已被调查。基于水下航行器的车身和非均匀流动，通过数值模拟对具有不同叶尖间隙尺寸（0.1、0.2、0.4、0.8 mm）的泵系统进行了评估和验证。初步的稳定模拟结果表明，增加叶尖间隙尺寸会降低压头的整体性能、效率、泵推力和消耗功率。在进一步的非定常模拟之后，我们揭示了由叶尖间隙引起的非定常动态性能，与水下航行器周围压力强度和压力脉动的相似分布特征有关。此外，泵中的压力强度和压力脉动随着叶尖间隙的增加而增加。分布特性的定量对比分析表明，护罩的叶片加载和报废效果是影响泄漏流量的关键因素。最后阐明了不同叶尖间隙下泄漏流的动态分布规律。