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| Numerical analysis of pressure fluctuation in low specific speed mixedflow pump |
| LI Yi-Bin, LI Ren-Nian, WANG Xiu-Yong, HAN Wei, GAO Qiang |
| (School of Energy and Power Engineering, Lanzhou University of Technology, Lanzhou, Gansu 730050, China) |
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Abstract In order to investigate effects of impellerguide vane interaction on pressure fluctuation in a low specific speed mixedflow pump, the threedimensional, unsteady turbulent flow in it was analyzed by using CFD code with the RNG k-ε turbulence model and sliding mesh technique under the design condition, and the pressure fluctuations at three monitoring points were obtained. Subsequently, the fluctuation signals were transformed into the frequencydomain to get their characteristics in terms of amplitude and frequency. Even though a positive slope head curve was observed under the 60% and 85% design flow rate conditions, the unsteady flow simulation based on the Reynoldsaveraged N-S equations failed to show this effect. It was shown that the maximum amplitude of pressure fluctuation is found at the tip of shroud of impeller, but the minimum one was located at the tip of the hub. The amplitudes of fluctuation at the entrance to impeller and at the monitoring points located at the tip in the gap between impeller and guide were as high as twice the magnitude of the amplitude observed at the tip of hub. Further, the pressure fluctuation exhibited increasing amplitude from the entrance of impeller to the outlet to guide vane, where the maximum amplitude with a low frequency was identified.
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Received: 09 October 2012
Published: 31 March 2013
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