Numerical Study on the Characteristics of Pressure Fluctuations in an Axial-Flow Water Pump

Zhi-Jun Shuai,Xiang-Yuan Zhang,Chen-Xing Jiang,Feng-Chen Li,Wan-You Li

doi:10.1155/2014/565061

Abstract

Flow induced vibration due to the dynamics of rotor-stator interaction in an axial-flow pump is one of the most damaging vibration sources to the pump components, attached pipelines, and equipment. Three-dimensional unsteady numerical simulations were conducted on the complex turbulent flow field in an axial-flow water pump, in order to investigate the flow induced vibration problem. The shear stress transport (SST) k-ω model was employed in the numerical simulations. The fast Fourier transform technique was adopted to process the obtained fluctuating pressure signals. The characteristics of pressure fluctuations acting on the impeller were then investigated. The spectra of pressure fluctuations were predicted. The dominant frequencies at the locations of impeller inlet, impeller outlet, and impeller blade surface are all 198 Hz (4 times of the rotation frequency 49.5 Hz), which indicates that the dominant frequency is in good agreement with the blade passing frequency (BPF). The first BPF dominates the frequency spectrum for all monitoring locations inside the pump.

Highlights

For a water pump, the pressure fluctuation and unsteady dynamic forces induced by the complex and rotating inner turbulent flow are one of the main reasons causing vibration of pump components and hydraulic noises
The fast Fourier transform (FFT) method was often used to obtain the spectra of pressure fluctuations as a function of position and flow rate in the posttest data analysis [1]
For a given impeller diameter, the dynamic load increases for offdesign conditions, especially for the low range of flow rates, whereas the progressive reduction of the impeller-tongue gap brings about corresponding increments in dynamic load

Summary

Introduction

The pressure fluctuation and unsteady dynamic forces induced by the complex and rotating inner turbulent flow are one of the main reasons causing vibration of pump components and hydraulic noises. Parrondo-Gayo et al [2] investigated the unsteady pressure distribution existing in the volute of a conventional centrifugal pump by means of four piezoresistive pressure transducers mounted at 36 locations around the front side of the volute casing Their experiments demonstrated a strong increase in the magnitude of dynamic forces and dipole-like sound generation in off-design conditions. Solis et al [7] studied numerically the influence of splitter blades and radial gap on the reduction of pressure fluctuation levels at the blade passage frequency in a volute type centrifugal pump. They employed unsteady Reynolds averaged Navier-Stokes (URANS) approach to solve the unsteady flow and pointed out the fact that assuming the flow

Methods

Results

Conclusion