Research On Pressure Fluctuation Of Series-parallel Centrifugal Pump Based On Clocking Effect

With the development of marine technology,better hydraulic performance,higher stability and lower vibration and noise has become the inevitable requirement of series-parallel centrifugal pump.It is necessary to carry out the study of clocking effect on series and parallel centrifugal pumps because clocking effect has a significant effect on improving pump hydraulic performance and reducing pump internal pressure pulsation.Numerical simulation was used to study the clocking effect on hydraulic performance of the series-parallel centrifugal pump by changing the clocking position of secondary impeller,or changing the clocking position of secondary guide vane,or both changing the clocking position of secondary impeller and guide vane.Plus,the influence of the secondary impeller clocking position on the pressure pulsation characteristics of the series-parallel centrifugal pump were also studied.The main research work and results are as follows:(1)The three dimensional model of the fluid domain in series-parallel centrifugal pump was established,and the mesh of fluid domain and mesh independent test were carried out.The original model was simulated and compared with the test to verify the feasibility of numerical simulation.(2)The relationship between the clocking position of the secondary guide vane together with the secondary impeller and guide vane and the external characteristic of the pump are obtained.(3)The influence of the secondary impeller clocking position on the hydraulic performance and internal flow characteristics of the series-parallel centrifugal pump was studied.The relationship between the secondary impeller clocking position and the head and efficiency of the pump is obtained.The internal flow field of the pump was changed with the clocking position of secondary impeller.In the series operating condition,the flow field inside the pump changes small.Under the condition of parallel operation,the resistance of the secondary flow path changed with the clocking position of secondary impeller,which changed the flow field.(4)It is found that changing the secondary impeller clocking position didn't change the law of pressure pulsation in secondary impeller and guide vane,only changes the time of peak pulse pressure in secondary impeller and guide vane.The pressure fluctuation of secondary and downstream fluid domain of volute without a common law due to multiple factors.The frequency characteristics of the first and secondary impeller and guide vane are not affected by the secondary impeller clocking position.The main excitation frequency of the pressure pulsation in the impeller is 10 times the pump rotational frequency.The main excitation frequency in the guide vane is the same as the passage frequency of the blade.The pressure fluctuation in the first and secondary volute,the reversing valve and the outlet tube has no common frequency characteristics at different clocking position.