Influence Of Guide Vane Number On Performance Of Bidirectional Shaft Cross-flow Pumps

The two-way shaft tubular pump device is a new type of ultra-low lift pump station structure,which motor is installed in the shaft.It has numerous advantages,such as simple structure,relatively high device efficiency,convenient maintenance and so on.With the application of shaft tubular pump device more and more widely,more and more research on it.The number of blades the commonly used two-way pump hydraulic model impeller is 4 pieces,and the number of blades is 5 or 7.For the convenience of installation,split-half structure is usually used in the prototype pump guide vane.It is difficult to divide 5 and 7 guide blades.For example,Longshan,Dahe Port and other pumping stations put forward whether the guide blade can be changed to 6 pieces However,if the number of guide blades is changed to 6,the number of impeller blades and the number of guide blades are not mutually qualitative,and there is a common divisor,which will make the pump device produce noise,vibration and other adverse effects.Therefore,it is of reference significance to research the influence of different guide vane number on the hydraulic performance,pressure pulsation and the bearing condition of impeller and guide vane.In this paper,the CFD technique is used to calculate the pump units’ forward and backward numerical simulation of different vane number(Zs=4,5,6 and 8)in the two-way shaft tubular pump device of Dahegang pumping station,Meanwhile,the hydraulic performance and internal flow field characteristics of the four schemes under three characteristic working conditions(forward:0.85 Q=240 L/s、Q=280 L/s、1.15Q=320 L/s;reverse:0.85 Q=230 L/s、Q=270 L/s、1.15 Q=310 L/s)are compared and analyzed,and the unsteady calculation of the pump device is carried out,and the pressure pulsation of the inlet and outlet section of the impeller and guide vane in the pump device is compared and analyzed.Then the axial force,radial force and torque data of impeller and guide vane are taken out and compared.Finally,a two-way model test was carried out on the pump unit at Zs=5 and 6 using a high precision hydraulic mechanical test bench to verify the accuracy of the numerical simulation.It is found that the head and efficiency of the pump device increase with the increase of the number of guide blades under the condition of small flow rate and design flow rate,the maximum is 2.609 m at Zs=8,and the efficiency is 68.24%.In the case of large flow,the head and efficiency decrease with the increase of the number of guide blades,and in the reverse operation,under the condition of small flow,the head difference is large,with the increase of flow rate,the head curve is gradually approaching.At the design condition,when Zs=4,6 and 8,the pressure pulsation of the outlet section of the positive and negative impeller will appear secondary wave peak,and the pulsation amplitude will be large.When the axial force of the impeller and the guide vane is an integer multiple of the number of the guide vane,the peak value of the pulsating peak will increase significantly,and The radial force of the guide vane decreases when the number of guide vane is even.The angle adjusting torque of single blade is less affected by the number of guide blades.When the number of guide blades is changed,the angle adjusting torque of blade is almost unchanged.