Study On Influence Of Structural Parameters Of Radial Guide Vane Back Blade On Performance Of Multistage Centrifugal Pump

The radial vane is an important static overcurrent component in the multistage centrifugal pump.It acts as a high-speed liquid stream collecting the impeller outlet and gradually transforms the energy into the next-stage impeller inlet.Studies have shown that the degree of hydraulic loss caused by fluid flow in the radial vane is almost the same as that in the impeller,while the design geometry of the back vane affects the hydraulic loss in the anti-leaf.In order to study the influence of the design parameters of the back blade on the single-stage hydraulic performance,this paper conducts a numerical study on the flow in a multi-stage centrifugal pump.On the basis of this,the secondary radial guide vane back blade was redesigned with the parameters of blade length,blade number and blade height as variables,and the flow in the pump was numerically calculated.The main research work of this paper is as follows:1.The research schemes of four radial vane back blade length parameters are established,which are d₁=238mm,d₂=285mm,d₃=315mm and d₄=325mm,respectively,and the numerical calculations are carried out under five different flow conditions.The flow of the radial vane back blade length in the multi-stage centrifugal pump is obtained,and the external characteristic performance is obtained.The internal flow law of the pump is analyzed.The results show that under the premise that the length of the back blade does not interfere with the fluid flow in the transition section,as the length of the blade increases,the volume of the vortex in the channel of the anti-guide vane decreases,the collision between the fluid at the inlet and the tip of the blade is alleviated,and the circulation phenomenon is weakened.The local hydraulic loss in the leaves decreases,and the single-stage lift efficiency increases.However,if the back blade is too long,it will interfere with the fluid flow in the transition section,and the velocity gradient of the anti-guide vane inlet will be aggravated,resulting in more local hydraulic loss.Therefore,the larger the length of the back blade,the better the single-stage hydraulic performance without exceeding the diameter of the base circle.2.The research schemes of the number parameters of the back blade of four radial vane models are established,which are Z₁=6,Z₂=7,Z₃=9 and Z₄=10,respectively.Under five different flow conditions,the numerical study has The above four kinds of blade numbers flow in a multi-stage centrifugal pump,and the external characteristic performance is obtained,and the internal flow law of the pump is analyzed.The results show that the hydraulic performance of the multistage centrifugal pump with more back blades than the original model is reduced.The flow in the anti-guide vane flow is separated from the flow in the front wall to form a large number of vortices distributed in each flow channel,while the increase in the number of back blades leads to an increase in the flow path,so the local loss caused by the vortex is the main cause of the decline in hydraulic performance.For a multi-stage centrifugal pump with fewer back blades than the original model,it has higher hydraulic performance under five flow conditions,and the inlet area of the flow passage is increased to make the fluid flow more smoothly from the transition section into the anti-guide vane.The collision between the fluid and the tip of the back blade is suppressed,and the generation of the circulation at the entrance of the anti-leaf blade is reduced.The research schemes for the height parameters of the back blade of four radial vane models are established,h₁=10mm,h₂=14mm,h₃=25mm and h₄=30mm,respectively.Under the five different flow conditions,the numerical study has The above four kinds of blade heights flow in a multi-stage centrifugal pump,and the external characteristic performance is obtained,and the internal flow law of the pump is analyzed.The results show that fluid blockage is common in the transition from the transition to the anti-leaf inlet,which causes severe local hydraulic losses.The research scheme of increasing the height of the radial vane back blade can alleviate the flow congestion at the entrance of the anti-guide vane,reduce the local high-speed area caused by the phenomenon,reduce the local hydraulic loss,and improve the single-stage hydraulic performance of the multi-stage centrifugal pump.