Pressure fluctuation near volute tongue and analysis of radial force characteristics of single and double volute pumps

In order to reveal the difference of hydraulic characteristics between single and double volute centrifugal pumps,their three-dimensional non-stationary turbulent flow was numerically simulated with commercial software FLUENT,RNG k-eturbulence model,and sliding mesh technology under different operational conditions.The pressure fluctuation near volute tongue was obtained and the frequency spectra at corresponding monitoring point for different volutes were analyzed.The results showed that the blade passing frequency dominated the pressure fluctuations near the volute tongue under design and large flow rate condition for single volute centrifugal pump.Under small flow rate condition,the frequency less than the blade passing frequency became dominative in the pressure fluctuations.Under condition of 60% design flow rate,the maximum pressure fluctuation amplitude was about 1.13 times larger than the amplitude at design flow rate.For the double volute pump the blade passing frequency dominated the pressure fluctuations near the volute tongue under conditions of design and off-design flow rate.Under conditions of60%,80%and 120%design flow rate,the pressure fluctuation amplitudes were respectively 6.59,3.12 and 4.55 times larger than the amplitude at design flow rate.Compared with the single volute pump,the double volute pump exhibited the ability to balance effectively the radial force,and the change of radial force at off-design flow rate was little.