Research On Vertical Submersible Axial Flow Pump Unit Of A Pump Station In Suqian City

Submersible axial flow pump,which could operate for a long time in water and dissipate the heat rapidly,has the characteristics of large flow and low speck,is used more and more widely in recent years.The pump device is used as a whole,to understand the internal flow of the actual operation,it is necessary to study understand its internal flow and pressure pulsation characteristics.Takes the pumping station project in Suqian City as an example,the internal flow characteristics of vertical submersible axial flow pump devices was carried out with two different intake flow paths which contain box-culvert and dustpan-shaped inlet flow passage.The performance curve of the two pump devices is predicted by numerical simulation.The internal flow conditions and hydraulic performance of the two pump devices is analyzed,then a better scheme is selected,and the internal pressure pulsation of which is analyzed.Main research contents and conclusions are as follows:(1)The efficiency of vertical submersible axial flow pump system with box-culvert inlet flow passage reaches maximum of 68.08%at the point of KQ=0.521,while the head H is 5.73m.The flow line in the inlet flow passage is relatively straight,but the deflection angle is large around the bell mouth,where there are flow and vortex phenomenon.The velocity circulation becomes large after the rotating impeller.The guide effect of the guide vane are poor,and there are refluxes on the back of the blade.The streamlines in the wellbore outflow conduit are more disorder,and there are vortexes.(2)The hydraulic performance of the box-culvert inlet flow passage of the vertical submersible axial flow pump system is good,the velocity circulation of water is large after the rotation of the impeller,and the hydraulic performance is decreased.The diffusion angle becomes large after the water flow from the diffusion guide vane.The weighted average angle at the exported cross section and the hydraulic loss rise,while the flow rate distribution uniformity is decreased;the hydraulic performance of the wellbore outflow conduit is poor.(3)The efficiency and head of the vertical submersible axial flow pump device with dustpan-shaped inlet flow passage are both higher than those of the pump device with boxculvert inlet flow passage.The flow patterns in the dustpan-shaped inlet flow passage is better and deflection angle around the bell mouth is smaller than those of the box-culvert inlet flow passage,and there are no vortexes.The backflow area of the leaf blade is reduced;the lowpressure area in the outlet flow channel is reduced,backflow and vortexes still can be seen.(4)The efficiency of the vertical submersible axial flow pump device with dustpanshaped inlet flow passage is higher than that of the pump device with box-culvert inlet flow passage,especially the flow rate distribution uniformity and speed weighted average angle at the outlet cross section of the inlet flow passage are higher than those of the vertical submersible axial flow pump device with box-culvert inlet flow passage,and the hydraulic loss of the outlet flow passage of the vertical submersible axial flow pump device is obviously better than that of the pump device with box-culvert inlet flow channel.(5)The pulsation intensity in the dustpan-shaped inlet flow passage is lower,and the regularity is not obviously.The pulsating strength at the inlet of impeller is larger,and the main frequency is consistent with that of the impeller.The pulsation intensity of impeller is gradually decreasing from the flange to the hub,and is gradually increasing from the inlet to the outlet cross section.The main frequency at the outlet of the impeller is consistent with that of blade passing frequency.The pulsation law of each monitoring point is different,and the pulsation intensity is lower than that of the impeller inlet;the pulsation intensity at the outlet of the guide vane is lower than that of the inlet of impeller,and the main frequency occurs in the point of 0.5 rotating frequency.The pulsation intensity in the outlet flow passage is lower than that of outlet of guide vane,and with less regularity.