Research On The Hydraulic Performance Optimization Of Guide Vane Of Centrifugal Pump Based On Area Gradient Control

Widely used in industrial and agricultural industry,centrifugal pump plays a significant role in this field.In recent years,with the continuous improvement of national requirements for resource conservation and environmental protection,higher requirements have been put forward for energy conservation and emission re duction of pump products.Guide vane,as an important flow passage part of segmental multistage centrifugal pump,has crucial impact on the hydraulic performance of the whole pump.With the purpose of reducing the hydraulic loss of guide vane and improve the efficiency of the whole pump,this paper uses the methods of theoretical analysis,numerical calculation and experimental verification to study the hydraulic optimization of the positive guide vane of guide vane.In order to improve the accuracy of hydraulic performance calculation of multistage centrifugal pump under multi-operating conditions,the calculation domain was divided into tetrahedral,hybrid and hexahedral grids,calculating with RNG ?-? turbulence model and Standard Wall Function,and comparing with the test results.The influence of different meshing schemes on the calculation accuracy was comprehensively evaluated from the coincidence of the calculation curve and the test curve.The results show that the accuracy of hybrid and hexahedral grids is higher than that of tetrahedral grids,and the accuracy of hexahedral grids is better than that of hybrid grids.Generally speaking,the scheme of grid generation adopts the hexahedral grid of the whole flow field,the RNG ?-? turbulence model and the standard wall function as the turbulence model,which is more suitable for the calculation of the hydraulic performance of multistage centrifugal pump.In order to reduce the hydraulic loss in guide vanes,this paper stud ied the influencing factors of hydraulic loss in guide vanes by theoretical analysis and numerical calculation.Firstly,with the help of theoretical analysis and formula derivation,it is clear that the direct factor affecting the hydraulic loss of guide vane i s the pressure gradient in the diffusion section,and the indirect factor is the area gradient in the diffusion section and the change the law of the flow direction;Secondly,the hydraulic performance of several rectangular section diffusion tubes with di fferent area gradient distribution laws was analyzed by numerical calculation.The results show that when the pressure gradient in the diffusion tube decreases gradually along the flow direction,the hydraulic loss also decreases correspondingly,and the c hange trend of pressure gradient can be controlled by adjusting the change trend of area gradient along the flow direction.The above theoretical analysis and research show that it is feasible to optimize the hydraulic performance of guide vane diffusion section based on area gradient control.Although the geometric parameters of guide vane are numerous and independent of each other,if the area gradient is taken as a variable,then there will be a certain relationship between these geometric parameters and the area gradient.No matter which geometric parameter of the positive guide vane change d,the area gradient would change correspondingly,and the area gradient do not change if multiple geometric parameters are adjusted at the same time Therefore,taking the area gradient as the control variable,the guide vane geometric parameters can be adjusted flexibly,as long as the area gradient change law meets the specific requirements,the specific impact of parameter changes on the hydraulic performance can be ignored.In order to study the influence of the area gradient of the diffuser on the pressure gradient and hydraulic loss,three schemes were respectively adjusted for the geometric parameters of the diffuser:(1)changing the number of blades of the guide vane and modifying the inlet and outlet area of the diffuser;(2)changing the based circle diameter of the guide vane;(3)changing the change rule of the section area of the diffuser along the flow direction.Through numerical calculation and analysis,the results show that: when the pressure gradient decreases,the flow field structure in the diffusion section can be significantly improved,and the hydraulic loss would be reduced;when the area gradient decreases,the pressure gradient in the diffusion section would be correspondingly reduced;when the area gradient decreased and the growth rate of the area gradient along the flow direction is gentle and nearly linear,the hydraulic loss in the diffusion section can be reduced to within the minimum range.Finally,the optimal hydraulic design scheme of guide vane was tested and verified.The results showed that the efficiency of the optimized multistage centrifugal pump at the design condition point and the small flow condition point is significantly improved.Compared with the original model,the efficiency of the design condition point was increased by more than 4%.It is proved that the optimization method based on area gradient control is feasible and reliable,which can provide theoretical reference a nd method guidance for the performance optimization of hydraulic machinery with guide vane.