Influence of impeller staggered arrangement on radial force and pressure fluctuation for a double-suction centrifugal pump

Yu Song,Guangtai Shi,Xiaobing Liu,Zhiyi Yu

doi:10.1177/1687814018781467

Abstract

Influence of impeller arrangement on performance, radial force, and pressure fluctuation for a double-suction centrifugal pump is investigated. In comparison of the original impeller with staggered angle α of 0°, the maximum improvement of pump efficiency is 2.19% for impeller with α of 30°, and the maximum improvement of pump head is 1.76% for impeller with α of 20°. The radial force vector on impeller is related to the staggered angle, and the phase angle of radial force vector is equal to the staggered angle. The staggered arrangement can effectively reduce the amplitude of radial force fluctuation. In comparison of case 0, the maximum amplitude of radial force fluctuation for case 30 reduces by 15.8%. The dominant frequencies of the radial force fluctuation for α = 0°, 10°, and 20° are fBP, while the dominant frequency for α = 30° is 2 fBP. An empirical formula is proposed to predict the radial fluctuation amplitude at specific staggered angle. For a point of the volute far from the exit volute, in comparison of case 0, the maximum amplitudes of pressure fluctuation for case 10, case 20, and case 30 are reduced by 13.1%, 49.8%, and 93.3%.

Highlights

Complex flow in centrifugal pumps involving secondary flow and reverse flow and the fluid-dynamic blades– tongue interaction is proved to be a main factor for the flow instability for single-suction centrifugal pump.[1,2,3] As a result, the operation of centrifugal pumps can result in the generation of unsteady radial forces and pressure pulsations,[4,5] which can affect the mechanical integrity of the pump, resulting in intense vibration and noise.[6,7]The radial force in pumps is inherently unsteady caused by the impulse of blades during rotating
The test apparatus is established as a close-loop water circulation, including the tested double-suction pump and a set of digital equipment
The performance curves obtained with the numerical model have been compared with experimental data to verify the accuracy of the numerical method

Summary

Introduction

Complex flow in centrifugal pumps involving secondary flow and reverse flow and the fluid-dynamic blades– tongue interaction is proved to be a main factor for the flow instability for single-suction centrifugal pump.[1,2,3] As a result, the operation of centrifugal pumps can result in the generation of unsteady radial forces and pressure pulsations,[4,5] which can affect the mechanical integrity of the pump, resulting in intense vibration and noise.[6,7]The radial force in pumps is inherently unsteady caused by the impulse of blades during rotating. Keywords Double-suction pump, staggered angle, performance, radial force, pressure fluctuation Four double-suction impellers with different arrangements are investigated, and the influence of impeller arrangements on performance, radial force, and pressure fluctuation is investigated.

Results

Conclusion