Energy Performance and Flow Patterns of a Mixed-Flow Pump with Different Tip Clearance Sizes

Yabin Liu,Yun Xu,Lei Tan,Yue Hao

doi:10.3390/en10020191

Abstract

Tip clearance between blade end and shroud is inevitable in pump operation and of great importance on pump energy performance and pressure fluctuation. As the tip clearance size increases, the head and efficiency of the mixed flow pump drop accordingly. The simulation results show that the development of a leakage vortex is observed as the tip clearance increases, and the trajectory of this leakage vortex remains in the same direction along the blade suction side for different tip clearances. With the increase in tip clearance size, the intensity of the leakage vortex is enhanced, and the separation between the main leakage vortex and the secondary leakage vortex is also strengthened. The leakage separation angle near the blade tip remains at the same value of 10° for different tip clearance sizes. As for the spectrum analysis, the maximum amplitudes of pressure fluctuations dramatically increase in the impeller when the tip clearance increases from 0.0 mm to 1.0 mm, and the dominant frequencies go from 145 Hz to 184 Hz due to the considerable leakage flow.

Highlights

IntroductionMixed flow pumps have the characteristics of wide operation ranges and high efficiency
Mixed flow pumps have the characteristics of wide operation ranges and high efficiency.they are widely used in the fields of water conservancy, hydropower engineering, urban water supply systems, power plant cooling systems and so on
The leakage flow caused by the tip clearance and its interaction with the main flow leads to a complex vortex structure and unstable flow in the impeller, which will reduce the energy performance of the pump

Summary

Introduction

Mixed flow pumps have the characteristics of wide operation ranges and high efficiency. They are widely used in the fields of water conservancy, hydropower engineering, urban water supply systems, power plant cooling systems and so on. The leakage flow caused by the tip clearance and its interaction with the main flow leads to a complex vortex structure and unstable flow in the impeller, which will reduce the energy performance of the pump. Kang et al [1,2] measured the flow field in tip clearance of a plane cascade by the five-hole probe method, and found that the vorticity of the tip vortex increased rapidly near the leading edge and reached its maximum value at a short distance downstream. Jang [4] investigated the vortex structure in a propeller fan using LDV measurements and proposed three vortex structures including the tip vortex, leading edge separation vortex and tip leakage vortex

Methods

Findings

Discussion

Conclusion