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Abstract
The complex three-dimensional turbulent flow field in a centrifugal water pump with three asymmetrical diffusers was numerically simulated. The characteristics of pressure and force fluctuations inside the model pump were investigated. Fast Fourier transformation was performed to obtain the spectra of pressure and force fluctuations. It indicates that the dominant frequency of pressure fluctuations is the blade passing frequency in all the sub-domains inside the pump and the first blade passing frequency energy (first order of blade passing frequency) is the most significant. The dominant frequency of pressure fluctuations at the location of diffuser outlet is featured by low frequency (less than 1 Hz), which may be due to the locally generated eddy structures. Besides, the dominant frequency force fluctuations on the impeller blades are also the blade passing frequency. The existence of the three asymmetrical diffusers has damping effect on the pressure fluctuation amplitude and energy amplitude of pressure fluctuations in the diffuser domain dramatically, which indicates that the diffusers can effectively control the hydraulically excited vibration in the pump. Besides, the prediction of the dominant frequency of pressure fluctuations inside the pump can help to utilize the pump effectively and to extend the pump life. The main findings of this work can provide prediction of the pump performance and information for further optimal design of centrifugal pumps as well.
Keywords
Centrifugal pump, flow-induced vibration, pressure fluctuation, numerical simulation
Date received: 31 March 2015; accepted: 6 June 2015
Academic Editor: MoranWang
(ProQuest: ... denotes formulae omitted)
Introduction
The centrifugal water pumps, a kind of widely used fluid machinery, play an important role in almost all industrial and agricultural fields. The flow inside a centrifugal pump is three-dimensional (3D) involving secondary flows and even complex vortical flow structures due to the complexity and asymmetry of the volute flow passage configuration. The turbulent flow will lead to vibration of the overall pump unit and alternating stresses of the impeller blades under design condition and even stronger under off-design conditions, which is considered as flow-induced instability. Not only the impeller but also the other components of the unit may suffer from serious damage due to flow-induced vibrations.
Rotor-stator interaction plays an important role in the investigation of the unsteady flow inside the water pump. Dring...