Multi-objective Hydraulic Design And Research On Energy Conversion Of Vortex Pump Based On Orthogonal Tests

Vortex pump is a kind pump of solid-liquid two-phase flow which is widely used in modern life,industry and agriculture.At the same time,vortex pump has the characteristics of simple structure,easy manufacture and stable operation.When the vortex pump transports the medium containing a large number of solid particles,the non clogging performance of the vortex pump is good due to the circulation flow caused by the structure of non blade cavity,and the wear degree of the blade is reduced accordingly.Therefore,the vortex pump is widely used in industrial slurry transportation,urban sewage,agricultural production and breeding.At present,the hydrocyclone pump has the disadvantages of low hydraulic efficiency and large energy consumption.Most of the vortex pump blade is semi open,the blade is installed in the back cavity,so the front pump cavity forms a blatless cavity.When the vortex pump is running,the movement of the fluid medium in the bladed cavity contains a variety of complex flow structures,which leads to the change of the internal hydraulic loss of the spiral case of the vortex pump.When the blade transmits energy to the fluid medium,the mechanical energy is not completely converted into the pressure energy of the hydrocyclone pump,but is lost in the conversion process of the through flow and the circulation flow.Therefore,it is judged that the circulation flow is the main reason for the decline of the overall efficiency of the hydrocyclone pump.In view of the characteristics of the above vortex pump,this paper studies and analyzes from the following aspects.In this paper,in view of the problem of low efficiency of vortex pump,two different types of defecting blades are used as the starting point.Through the structural characteristics of the defecting blades of the vortex pump,the hydraulic performance of the defecting blades is simply optimized.The important structural parameters are selected,and the orthogonal test design is carried out according to the different structural parameters.After the combination of orthogonal design,the three-dimensional model is built by Pro/E,and the overall performance of the vortex pump is analyzed and predicted by CFD software.Through the numerical calculation results,the optimal combination form of the vane structure of the vortex pump is found,and the main structural parameters that affect the performance of the vortex pump are found.At the same time,in order to improve the reliability of CFD numerical calculation results,relying on the water pump Laboratory of LanzhouUniversity of science and technology,a horizontal 150wx-200-20 vortex pump test bench was built for test.The error between the test results and the numerical results is less than 6%,so the numerical results in this paper are reliable.First of all,when using the orthogonal test method to optimize the design for the first time,it is found that the primary and secondary order of the influence on the flow of the highest efficiency point of the vortex pump is as follows: whether the blade is wedge-shaped,blade angle type and blade break point position;the primary and secondary order of the influence on the head is as follows: whether the blade is wedge-shaped,blade break point position and blade angle type;the primary and secondary factors of the influence on the efficiency are as follows: whether the blade is wedge-shaped,blade break point position and blade angle type.Finally,the optimal combination of blade structure is considered.The blade angle type is R30F60,the folding point position is 2/3 of the blade,and the wedge blade is adopted.Secondly,multiple objectives and factors are selected according to the defecting blade structure.Secondly,the multi-objective hydraulic optimization of the defecting blade structure of the vortex pump is carried out by using the orthogonal test method.Four important factors are selected according to the structural characteristics of the blades,and each factor is taken at three different levels.Therefore,nine different combinations can be made for the defecting blade structure according to the orthogonal test method.Two different types of defecting blades,R-F(forward bend)and F-R(backward bend),were optimized by orthogonal test.Through the analysis of the external characteristic curve,internal flow state and the range of orthogonal test,the optimal combination scheme is that the angle is R30F30,the bending point is 2/3of the whole impelle blade,the chamfer radius is 3mm,and the axial wedge type is adopted.The overall performance of the front curved blade is better than that of the back curved blade.Under the design flow Q,the efficiency of the optimal combination scheme is 20.24% higher than the design value,the head is 31.70%higher than the design value,the shaft power is 3.26% lower than the design value,and the performance parameters meet the design requirements.Finally,taking two different types of defecting blades as breakthrough points,combined with the triangle theory of blade inlet and outlet speed,the paper makes a comparative analysis and Research on the work process and energy loss process of different defecting blades of the vortex pump,so as to find the energy loss transfer mechanism under these two different blade types.It is found that for the efficiency of vortex pump,the efficiency of backward curved blade is higher than that of forwardcurved blade before the design flow point,and the efficiency of forward curved blade is higher than that of backward curved blade after the design flow point.