Research On Vibration Characteristics Analysis Of Aero-Engine External Pipeline And Optimization Of Clamp Layout

The external pipeline system of aero-engine undertakes the task of transporting fuel oil and hydraulic oil,and plays an indispensable role in aero-engines.The external pipeline system of an aero-engine is excited by the engine rotor,aerodynamics,and combustion chamber when it is working.When the frequency of the external excitation is close to the natural frequency of the external pipeline system of the aero-engine,the pipeline system is prone to resonance.Due to its complex working environment,pipeline system vibration problems often occur,and pipeline vibration faults have become one of the main sources of aero-engine failures.Therefore,in order to improve the safety performance of the aircraft,it is necessary to analyze the pipeline vibration problem and provide a solution with application value.At present,designers mainly use design experience to adjust the installation quantity and installation position of the clamps on the external pipeline of the aero-engine to improve the pipeline vibration performance.When designing the external pipeline system of aero-engines,switching the design model back and forth between CAD and CAE software inevitably reduces work efficiency and lengthens the design cycle.In order to solve the above dilemma,it is necessary to study the modeling method of the aero-engine external pipeline system,the influence factors of vibration and the optimization strategy of the clamp layout.On the basis of the theoretical basis,we will develop a set of software for pipeline vibration analysis and clamp layout optimization that meets the needs of the enterprise,and realize the integration of design and analysis.The main research content of this topic is as follows:(1)Pipeline system dynamics modeling and experimental verification.Taking the space elbow and clamp as the research object,four kinds of finite element modeling methods of clamp restrained on the pipeline are proposed,and the spring element equivalent stiffness method is discussed.Carry out the clamp stiffness test experiment,and the measured experimental data is used to model the pipeline system.The evaluation of the modeling difficulty,modeling efficiency and modeling accuracy of the four modeling methods proves the feasibility of the spring element equivalent stiffness method.Pipeline system dynamics modeling and experimental verification.Taking space elbows and clamps as the research objects,four kinds of finite element modeling methods of clamps on pipelines are proposed by the experience summary method,and the spring element equivalent stiffness method is discussed.Carry out the clamp stiffness test experiment as the modeling data support.The modeling difficulty,modeling efficiency and modeling accuracy of the four modeling methods are evaluated,and it is concluded that the spring element equivalent stiffness method has a certain feasibility.Carry out free and restrained modal tests,using a combination of simulation and experiment to verify the validity and accuracy of the spring element equivalent stiffness method.A modal percussion test was carried out,and the effectiveness and accuracy of the spring element equivalent stiffness method were verified through a combination of simulation analysis and test.(2)Research on the influence factors of pipeline system vibration and realization of simulation analysis.Taking the space elbow and clamp as the research object,the main research is to study the influence of the assembly direction,assembly quantity and assembly position of the clamp on the pipeline on the vibration of the pipeline,and lay a theoretical foundation for the subsequent optimization of the clamp layout.Based on the finite element modeling of the single-joint clamp,the modeling method of the double-joint clamp is derived,and the difference between the double-joint clamp and the single-joint clamp on the vibration of the pipeline is compared.Study the influence of different external excitations on the vibration response of the pipeline system.(3)Optimized design of the clamp layout on the pipeline.Taking the maximization of the first-order natural frequency of the pipeline system as the optimization goal,the ANSYS optimization module is used to optimize the layout of the clamp on the local pipe section of the spatial elbow.An improved genetic algorithm that can increase the speed of iterative convergence is proposed,and the accuracy of the algorithm is verified by comparison with the optimization results of the ANSYS optimization module.A global optimization strategy for the layout of the clamp on the spatial elbow is proposed,and the first-order optimal frequency of the clamp under the layout of all pipe sections is obtained through the above-mentioned improved genetic algorithm.With the goal of maximizing the first-order natural frequency of the pipeline system and minimizing the amplitude of the pipeline harmonic response,the second-generation non-dominated sorting genetic algorithm(NSGAII)is used to optimize the layout of the clamp,and the optimal solution of Pareto for the position of the clamp is obtained set.(4)Pipeline system vibration analysis and clamp layout optimization software.Combining the above methods and key technologies,using C#as the development language,based on the secondary development of UG and the secondary development of ANSYS,realize the pipeline system vibration analysis and clamp layout optimization software.Through the research in this paper,a finite element modeling method suitable for the external piping system of aero-engines is proposed,the influence of the layout of the clamp on the vibration characteristics of the space elbow is found,and the local and global optimization strategies of the clamp on the space elbow are studied.The research work in this paper can provide data reference and technical support for the vibration analysis of the external piping system of aero-engines and the optimization of the clamp layout.