Study On The Effect Of Blade Angle On Plastic Centrifugal Pump Performance Based On Fluid-structure Interaction

Plastic centrifugal pump is widely used in various fields of national economy because of its high quality performance.Since the impeller material is mostly made of polymer materials such as polyvinylidene fluoride and reinforced polypropylene,the impeller strength is insufficient.When the fluid flows through the impeller,the interaction between the flow and the impeller will cause deformation and even lead to the structural damage of the impeller.The blade angle is the key structural parameter affecting the performance of the plastic centrifugal pump.The present research does not effectively relate the blade angle design to other structural parameters,and the relationship between the blade angle and the performance parameters of the plastic centrifugal pump has not been studied.In this thesis,the influence of blade angle on the performance of plastic centrifugal pump is studied based on the theoretical research,numerical simulation and pump performance experiments.The main research contents of this thesis include:(1)Based on velocity modulus method,the hydraulic design of the flow passage components of plastic centrifugal pump is carried out,and the two-dimensional model and three-dimensional model diagram of the flow components are established.(2)The flow field of the impeller model under different working conditions is simulated and the simulation results are analyzed by means of ANSYS CFX,then the influence of different fluid loads on the solid structure under design conditions on the structure characteristics of the impeller is studied by virtue of ANSYS Workbench.The results show that the working pressure of the plastic centrifugal pump should not exceed 5atm,otherwise the impeller structure will be damaged.(3)Impeller models with different exit angle are established to study the influence of the exit angle on the performance of plastic centrifugal pumps,and fluid-solid coupling for different impeller models is utilized to study the influence of the exit angle on the structural characteristics of the impeller.The results show that:When the exit is 35°,the plastic centrifugal pump can reach the highest efficiency value of 81%and the highest head of 35m;through fluid-solid coupling,it is found that the maximum deformation caused by the flow field load on the impeller increases with the increase of the exit angle.(4)According to the Stepanoff velocity modulus method,a wrap angle design method is proposed.By using this method,the corresponding wrap angle?=122° is obtained when the exit angle ?2=30°.Based on the design wrap angle,considering the import pre-rotation,the blade inlet angle design is associated with blade structure parameters,and the blade inlet angle design method is proposed.When the ?=122° is obtained,the corresponding inlet angle is ?1=7°.In order to study the influence of different inlet angles on the performance of plastic centrifugal pumps,the inlet angle is changed to establish multiple sets of impeller models.The results show that with the increase of the inlet angle,the efficiency and head of the plastic centrifugal pump are reduced.Under normal pressure load,the deformation of the impeller first decreases and then increases,and when?1=13°,the total deformation of the blade is the smallest.(5)Other structural parameters of the plastic centrifugal pump are unchanged,with the minimum hydraulic loss and the minimum NPSHr as the objective function,the blade placement angle is optimized,and the optimized inlet and outlet angles are:?1=19°,?2=33°.(6)The experiment is carried out on the model,and the performance parameters of the plastic centrifugal pump are obtained.The accuracy of the simulation results is verified,and the influence of the blade placement angle on the pump performance is summarized from the experimental data.The main innovations of this thesis are as follows:(1)Determine the maximum working pressure of the plastic centrifugal pump based on fluid-solid coupling,and study the influence of the outlet angle on the structural characteristics of the plastic centrifugal pump under different pressure loads.(2)Establish the design method of blade inlet angle by closely correlating impeller inlet and outlet parameters,and propose the wrap angle design method in the research process.(3)Based on the blade inlet angle design method,with the highest hydraulic efficiency and minimum NPSHr as the objective function,the blade angle is optimized to determine a high quality impeller model.