Numerical Analysis of Pressure Fluctuation in Circulating Water Pump Using CFD

Pressure fluctuations acting on centrifugal pump contain a lot of dynamic information, such as rotor-stator interaction, vortex, backflow, and so on. By CFD method, calculations of three-dimensional unsteady flow in the suction chamber, impeller, annular chamber, inlet and outlet were conducted with sliding mesh technology. For the simulation of inner flow field, a commercial code Fluent had been used to predict the pulsating pressures. The shear stress transport turbulence model (SST k-ω) was confirmed through comparison with the hydraulic performance experiment. The change of static pressure was recorded by means of virtual sensors placed at the impeller-annular chamber interface and the tongue. And the pulsating pressures in the impeller passage were recorded to reflect its flow state. Then, amplitude domain analysis and frequency domain analysis were conducted to process those fluctuating pressure signals obtained under different opening conditions. The results indicate that the effect of rotor-stator interaction and vortexes to pressure fluctuations in flow field is obvious. The pressure fluctuation around impeller-chamber interface and tongue is affected by the interaction between blade and tongue definitely, and the various positions of the blade relative to the tongue lead to different trends of variation of pressure distribution. The primary source of pressure fluctuation in the impeller passage is associated with vortexes.