The Study On The Hydraulic Performance And Excitation Characteristics In High Pressure Sea Water Desalination Pump

The seawater desalination project plays a vital role in the national economic and has a significant effect on people's life and production as pure water had been shortage.And multistage seawater desalination pump is quite important sector in seawater project,whose function is very crucial.With popularization of seawater desalination project and increasing volume for desalinated water per one day,multistage high-pressure pump has significantly prominent advantages comparing with other pumps like plunger pump.To study multistage high-pressure pump could not only acquired its inner flow characteristics and unveiled the principle of excited pressure pulsation,but also pave the way to design high hydraulic performance and low-pressure pulsation pump.The first stage in a multistage high-pressure seawater desalination pump was carried out by computational flow dynamic.Two different mediums took account into simulation.The mounting axial position and angle of radial vanes are optimized,which their hydraulic performance,inner flow and excited characteristics are analyzed and step into low noise hydraulic design for high-pressure pump eventually.The main workload and conclusion are below:Two mediums,seawater and pure water,are implemented in this pump.Pump head & hydraulic efficiency are predicted,the impeller blade load is analyzed,and the difference between two mediums of internal flow in diffuser and volute are depicted in detail meanwhile severe asymmetry of housing is one of the main reasons causing hydraulic lossUnsteady simulation was carried out with two mediums for three typical flow rates,which the pressure pulsation in time domain and frequent domain internal flow are acquired.There exists big difference between two mediums at part flow rate,but a little error at nominal and large flow rates.The pressure fluctuation in frequent domain with pure water is analyzed,which there is a difference between volute and diffuser that the amplitude at blade passing frequency is prominent and the one at four times blade pass frequency is second prominent as well.The mounting axial position for diffuser has significant influence on its external performance,hydraulic loss in diffuser and volute,and pressure fluctuation characteristics in time and frequent domain.The closer the diffuser central plane to volute outlet center,the higher hydraulic efficiency is.The hydraulic loss in diffuser and volute increase with flow rate increasing.The mounting axial position has no effect on pressure pulsation in pump.It is demonstrated that there is a good pressure pulsation performance hydraulic model while the distance from diffuser central plan to volute outlet center is in a certain range.The mounting angle of diffuser has a little bit influence on pump head but more little bit on hydraulic efficiency.The case,+3°,has a great efficiency.The error of hydraulic loss between different angles is quite small relatively.The areas of high vorticity become smaller and the vorticity intensity is going down when the mounting angle of diffuser move around anticlockwise.There is big difference about pressure fluctuation energy for angles and it is lower pulsation level when diffuser trailing edge is located at the left of volute central line.