Research On Pre-deformation Design And Optimization For Low Pressure Stage Blade Of Industrial Steam Turbine Under Multiple Working Conditions

Industrial steam turbine is an important power equipment in industrial production.Due to its compact and reliable structure,safe operation,adaptable operating conditions and good thermal economy,it is widely used in electric power,navigation,transportation,chemical and metallurgical industries,holding a very important position in industrial production.During the service period,the performance of rator blade plays a crucial role in the overall energy conversion efficiency of the unit.Whether the blades can realize the efficient conversion of energy will directly affect the performance and market competitiveness of the entire set of equipment,especially for the low pressure cylinder.Therefore,the research on the design method of low pressure stage blade for industrial steam turbine is of great significance.In this paper,in order to reduce the performance degradation of industrial turbine low pressure stage blades under the influence of complex loads,the pre-deformation design method of low pressure stage blades for industrial steam turbine was put forward with the reconstruction method of hot blade,correction method of cold blade and pre-deformation optimization method for multiple operating conditions of blades studied in detail,and the design results were verified by numerical simulation.The main contents of this paper are as follows:In the first chapter,the development history of design method for steam turbine blade is summarized,and the importance of pre-deformation design of low pressure blade in industrial steam turbine is expounded.The research status of the steam turbine operating conditions analysis,the effect of blade deformation on its own performance and other parameters of the unit,blade shape analysis and pre-deformation design is reviewed,and the shortcomings in the existing methods are pointed out.This chapter confirms the research contents,gives the organizational structure of the full text.The second chapter studies the basic method of blade deformation analysis based on the cold/hot blade type deviations.The theoretical basis of the hot blade remodeling and analysis method and the quantification standard of the hot blade type deviation are analyzed.The iterative process of the analysis method of the cold/hot blade deviation are expounded,and the influence of the working parameter on the blade deviation analysis result is also pointed out to provide a theoretical basis for the pre-deformation design of low pressure stage blades of industrial steam turbines.In the third chapter,on the basis of taking into account the characteristics of the variable stiffness of blades and the aerodynamic loads on the surface of blades,the nonlinear finite element method is used to reconstruct the hot blade.The difference between the geometrical shape and the aerodynamic load is compared between the hot blade and the theoretical blade.The influence of the elastic deformation of the blade on the geometrical shape and the aerodynamic load is analyzed.In the fourth chapter,a cold blade correction method based on load-space hybrid compensation is proposed.Based on the aerodynamic load data extracted from the hot blade surface,the correction method of the cold blade is improved.By comparing the difference between the hot blade and the theoretical blade after the different correction methods,the correction effect of the proposed method is verified.According to the load-space hybrid compensation method,the design of the pre-deformation design method is improved.The design efficiency of the two predecessor design methods is compared with the maximum deviation of the corresponding mesh node as the detection standard.In the fifth chapter,the optimization of the blade pre-deformation design under multiple operating conditions is studied.The method of entropy weight Vague set is introduced into the analysis of multiple operating conditions of steam turbine blades.The sensitivity of each condition characterization index is analyzed by information entropy theory.Based on the design requirement and design experience,the satisfaction degree of design scheme is obtained.The combination optimization method of pre-deformation design scheme is proposed based on the score function according to the matching degree of each scheme.The effectiveness of the method is verified through numerical simulation analysis.The sixth chapter summarizes the contents of the full text of the research,and prospect the further research direction of the subject.