| Shangwuxu Port Pumping Station is located in Dongxing Town,Jingjiang City,Taizhou City,Jiangsu Province.It is mainly responsible for the flood control and drainage safety of Dongxing Town and the improvement of river water environment.The pumping station and its supporting rivers have become the main drainage infrastructure for the western area of Dongxing Town.After completion,it will create conditions for diversion of water in the area to improve the water environment.The Shangwuwei Port Pumping Station has the dual pumping function requirements of draining water and lifting water.The pumping station uses a two-way vertical axial flow pump device structure.The internal flow pattern of the flow passage of the bidirectional vertical axial flow pump device is complicated.The bottom of the box-culvert bidirectional water inlet flow passage is easy to produce bad flow patterns such as vortex,which reduces the operating efficiency of the unit,and even induces vibration and noise of the unit,which affects the service life of the unit.The numerical calculation of the flow field in the vertical axial flow pump device is of great significance.Through numerical simulation of the full flow passage of the same size of the two-way vertical submersible axial flow pump device used in the Shangwuwei Port Pumping Station,the flow-through components of the two-way vertical axial flow pump device are analyzed when the two-way vertical axial flow pump device operates in the forward and reverse directions.Internal flow characteristics;analysis of the pressure pulsation characteristics under different characteristic flow conditions during forward and reverse operation;clarified the pressure pulsation evolution law of the flow structure of the pump device during forward and reverse operation.The main conclusions are as follows:(1)After verification by numerical simulation,When the blade angle of the two-way vertical axial flow pump is+1.2°,It can meet the flow requirements of different head conditions.In forward operation(diversion),the design working condition flow is 7.0m3/s,the total pump head is 2.30m,the device efficiency is 57.55%,the maximum working condition flow is 6.7m3/s,and the total pump head is 2.72m.The device efficiency is 60.36%.In reverse operation(drainage),the design working condition flow is 6.7m3/s,the total pump head is 2.73m,the efficiency is 60.11%,the maximum working condition flow is 5.5m3/s,the total pump head is 4.25m,and the efficiency is 67.04%.(2)When the pump device is running in the forward and reverse directions,the internal streamline of the box-culvert two-way water inlet flow passage is straight and there is no obvious vortex.There are two small vortices in the section of the impeller inlet,which has little effect on the flow pattern of the impeller inlet.When the pump device is running in the forward direction,the overall flow state of the impeller blade surface is good,and there is partial flow at the outlet side of the suction surface,and the streamline drift position is the most serious at the suction side of the suction surface at the maximum working condition when the pump is running in the reverse direction.The flow pattern inside the box-culvert two-way outlet passage is poor,and there are large-scale vortices at the entrance of the box-culvert two-way outlet passage,which seriously affects the efficiency of the pump device.(3)In the two-way vertical axial flow pump device,the hydraulic loss of the inlet flow passage in the forward operation accounts for the pump device head ratio of 6.45%under the design working condition and 5.07%under the maximum working condition;The hydraulic loss ratio of the water passage is 5.05%under the design conditions and 2.08%under the maximum conditions.The hydraulic performance is better.The hydraulic loss of the outlet passage is relatively large.The hydraulic loss ratio of the outlet passage of the pump device is 43.21%under the forward operating design condition,and 35.02%under the maximum operating condition;the hydraulic loss ratio of the outlet passage under the design operating condition is reversed.34.08%,15.81%at the maximum working condition.(4)Predict the cavitation performance of the impeller blades of the pump device.The static pressure value distribution at different chordal positions of the impeller pressure surface is basically the same.Under the four working conditions,the surface static pressure of the impeller suction surface is from the hub to the flange.Gradually increase,the static pressure value at the impeller flange reaches the maximum value on the suction surface and pressure surface within the range of 10%chordal position.By calculating the necessary cavitation allowance of pump devices under different working conditions,it runs in the reverse direction.The cavitation margin of the maximum working condition is significantly higher than other working conditions,the cavitation performance is the worst,and cavitation is prone to occur.(5)The internal flow characteristics of the bidirectional vertical axial flow pump device in forward and reverse operation are obviously similar,but the pressure pulsation characteristics are different due to different positions.In the forward operation,the pressure pulsation frequency of each monitoring point under different working conditions is larger than that of the reverse operation,but the amplitude is significantly lower.The pressure pulsation of each monitoring point at the impeller is greatly affected by the rotation of the impeller.The pulsation period is the same as the rotation period of the impeller,and the amplitude of the monitoring points becomes larger when the impeller period alternates.The pressure pulsation characteristics at the inlet and outlet of the impeller and the exit of the guide vane body have certain similarities,and the pressure pulsation characteristics of different working conditions are similar when running in the same direction.The pressure pulsation amplitude of each monitoring point of the condition is greater than the design condition. |
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