| Blade is an important component of the rotating machinery and plays an important role in the performance of the equipment.It has a wide range of application in fields such as water conservancy,civil use,and national defense.With the advancement of industry and the proposal of Made in China 2025,the design and manufacture of blades will meet higher requirements.Designing blades with better performance and higher energy efficiency is an inevitable requirement.For this reason,this paper optimizes the design of the plane shape and space surface of the blade,and studies the influence of the blade surface quality on the equipment performance.Based on computational fluid dynamics(CFD),this paper uses CFD numerical simulation technology,combining with the initial test of external characteristics of centrifugal pump to optimize the design of blades for ET3 type vehicle centrifugal cooling pump.Before the optimization work is carried out,centrifugal pump performance measurement tests were conducted,and comparative data of numerical simulations were obtained.A numerical model is established to study the effects of grid independence,dynamic and static boundary positions,flow field steady-state computation and unsteady-state computation,and to compare measurement test data to ensure the accuracy of the calculation model.Research on the optimization of the plane shape of centrifugal pump blades is carried out in this paper.In order to improve the automation degree and optimization efficiency of the optimization system,grid deformation technology is introduced into the optimization platform.An optimization system based on experimental design method,approximate model construction,intelligent optimization algorithm and grid deformation technology is designed.The BBD test design method is selected to obtain sample points;an improved response surface method is used to construct an approximate model between the sample points and the response;sample point information is used to evaluate the type of the approximate model,and a quadratic fit function with the best fitting effect is selected.This paper uses different types of test functions to test and evaluate genetic algorithm,particle swarm algorithm,and bat algorithm based on genetic algorithm,according to the test results,the bat algorithm based on genetic algorithm is selected as the optimization algorithm of the system.The study uses the optimization system to optimize the plane shape of the blade,selects the blade structure to control the vertex displacement as the design variable,head and efficiency of the centrifugal pump as the optimization goal,the optimization results are compared and analyzed,the optimization effect is obvious,and the optimization work efficiency is improved.The refinement and optimization of the space surface of the centrifugal pump blades is carried out.The optimization efficiency of the optimization system based on adjoint method is higher.Compared with traditional method,the optimization system no longer pays much attention to the number of design variables and does not require much sample information.It only needs flow field information and solution of adjoint equation for obtaining the sensitivity of design variables based on the objective function of flow field information,compared with traditional methods,the amount of calculation is drastically reduced.An optimization platform based on adjoint method,gradient optimization algorithm,grid deformation technology and CFD technology is built;the gradient of objective function on the placement of grid deformation point is deduced;this paper respectively uses the test function to test and evaluate the FR,PRP methods in the conjugate gradient algorithm and the DFP,BFGS methods in Quasi-Newton algorithm,the test results show that BFGS Quasi-Newton algorithm is most prominent in optimization ability.The optimization platform is used to optimize the space surface of the centrifugal pump blades,the torque of the fluid on the impeller is taken as the optimization goal,and the displacement of grid point of blade structure is taken as the optimization parameter.The optimization results show that,compared with traditional method,the optimized method can better capture slight changes in the shape surface,the calculation amount is small,the optimization efficiency is high,which indicates the effectiveness of the optimization method.The research on the influence of blade surface roughness on the performance of centrifugal pumps is carried out.The source of blade surface roughness is analyzed from two aspects: blade processing and the use of equipment.The roughness parameters are introduced into the numerical model by using the velocity calculation method of the fluid in the near wall region to study the effect of roughness on the flow field information.The influence on the performance of the equipment is mainly examined from two aspects: overall roughness and local roughness of the blade.The research results show that the surface roughness of the blade has a direct influence on the equipment performance.The basic performance is that,with the decline in the quality of blade surface,the equipment performance is simultaneously decreasing.For different roughness range,the decline in performance is different;different rough surface area of the blade has different influence degree on the performance of the equipment,the pressure bearing surface has a greater influence than the back-pressure surface.On the pressure bearing surface,the influence of the roughness of the entrance area and the exit area on the performance is not as great as that of the middle section.Through the research work of this paper,the design method and system of blade optimization have been developed,which can provide the blade designers with optimal design ideas and technical support,and is beneficial to blade manufacturing and maintenance. |
