| Due to its impeller shrinkage,a cavity is formed in the axial space of vortex pump.It makes the fluid in the pump to form unique flow structure--circulating flow and through flow.The unique flow structure of the vortex pump not only makes the fluid with large solid particles,fibers,high viscosity and high gas-content have good flow capacity and no-clogging,but also can reduce the damage of cavitation to the vortex pump.Therefore,it is widely used in agricultural and industrial production,sewage treatment,chemical industry and other fields.The vortex generated by circulating flow and hydraulic impact in the vortex pump will increase the energy loss,so the efficiency of the vortex pump is reduced.In this paper,without affecting the flow of solid particles,the flow characteristics of the vortex pump are changed by the use of an additional inducer,especially the change of the flow pattern of the circulating flow in its flow structure,so as to improve the performance from the internal flow mechanism of the vortex pump and make it reach the optimal.In addition,the relationship between the flow law and mechanical characteristics of the vortex pump is studied and analyzed.The specific contents and main conclusions are as follows.In this study,the 150WX-200-20 vortex pump was used as the prototype pump.A screw centrifugal inducer vortex pump is designed on the premise of ensuring good non-clogging in the delivery of multiphase fluid.Analysis of the numerical results of the vortex pump before and after the screw centrifugal inducer is added under different working conditions shows that the pressure difference between the inlet and outlet of the vortex pump increases significantly and the head of the pump increases significantly under the double work of the screw centrifugal inducer and impeller.The fluid entering the impeller changes from axial flow to radial flow under the action of the inducer,and the movement direction of the fluid in the impeller does not change significantly,making the fluid entering the impeller more evenly distributed.The performance and internal flow characteristics of the screw centrifugal inducer vortex pump are different under different blade types and blade numbers.In this paper,the efficiency and flow characteristics of screw centrifugal inducer vortex pump under three types of vane: curved vane,forward bent vane and back bent vane are studied.Among them,the inner flow of forward bent vane vortex pump is moreuniform and the efficiency is higher.By analyzing the variation law of the efficiency of the screw centrifugal vortex pump with different blade folding point and angle of inclination,it is concluded that the angle of inclination is the main factor causing the change of efficiency,while the fold point position is the secondary factor.By changing the number of inducer blade,it can be found that the head and efficiency of the double-blade inducer vortex pump are higher than that of the single-blade inducer.And the efficiency curve of the vortex pump is more stable with the change of flow,which can more effectively restrain the circulating flow and strengthen the through-flow.Based on the study of the flow mechanism of the inducer vortex pump,the change of the mechanical characteristics of the pump with and without the inducer is analyzed.The results show that the pressure pulsation near the tongue is more drastic and the amplitude is larger.However,the added inducer can reduce the pressure pulsation amplitude of each monitoring point in the circumferential direction of the volute.The impeller and the inducer adopt an integrated structure,the axial force between the components is well balanced.Meanwhile,the inducer transforms the fluid in the bladeless cavity from axial direction to radial motion.Thus,the axial force is effectively weaken and the stability and safety of the pump system in the operation process is improved. |
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