Vibration Analysis And Multi-objective Optimization Design For Air Conditioning Pipeline Of High-speed Train

The high-speed train air-conditioning unit is an important part of the high-speed train air-conditioning system.Its reliable operation is essential to the stable operation of the air-conditioning system of high-speed trains and the safe running of high-speed trains.The cause of fatigue damage to the pipeline system in the air conditioning unit is that it has withstood the long-term excitation of the compressor body vibration and the pressure pulsation in the pipeline.The damage of the pipeline makes the refrigerant leak and affects the reliable operation of the air conditioning unit and reduces the service life of the air conditioning unit.When the pipeline is severely damaged,this may cause a high-speed train traffic accident.Therefore,it is necessary to analyze the vibration problems of the air-conditioning unit pipeline system of high-speed trains,and the multi-objective optimization design of the air-conditioning unit pipeline structure,which not only improves the vibration of the air-conditioning unit pipeline system,but also reduces the weight of the pipeline and reduces the manufacturing cost.The research content of this thesis is of great significance to improve the operational reliability of air-conditioning units of high-speed trains and to reduce the quality of the air-conditioning unit piping system.First of all,this thesis makes a theoretical analysis of the vibration of the air conditioning unit piping system based on structural dynamics theory and fluid-structure coupling theory.Then,this thesis takes the pipeline system of a certain type of high-speed train air conditioning unit as the research object.This thesis carries out modal analysis and harmonious response analysis on it by using the finite element simulation software ANSYS Workbench.This thesis obtains the natural vibration characteristics of the air conditioning unit piping system based on modal analysis,and this paper focuses on the analysis of the influence of the flowing refrigerant in the pipeline on the natural vibration of the air conditioning piping system.This thesis obtained the vibration displacement value and vibration stress distribution of the air conditioning unit pipeline system based on harmonic response analysis,and this thesis analyzed the compressor body vibration,the pressure pulsation of the refrigerant in the pipeline and the different operating conditions of the high-speed train In these three cases,the vibration displacement value and vibration stress value of the air conditioning unit piping system.Finally,this paper proposes a method that can reduce the vibration displacement of the pipeline,reduce the vibration stress of the pipeline and reduce the weight of the pipeline.This thesis selects the pipeline structure parameters that have a significant effect on the maximum vibration displacement and maximum vibration stress of the pipeline system based on the orthogonal test design,and the second-order response surface approximation model of the maximum displacement value,the maximum vibration stress value and pipeline weight of the pipeline system and the significant structural parameters has been fitted.This paper optimizes the second-order response surface approximation model based on the non-inferior sorting genetic algorithm(NSGA-II).In the end,this thesis obtained the most optimized pipeline structure design plan.This thesis compares and analyzes the finite element simulation results of the air conditioning unit piping system before and after optimization.The calculation results show that the optimized maximum vibration displacement value,maximum vibration stress value and pipeline weight of the suction pipe and exhaust pipe decreased by 61.59%,55.91%,26.39% and 67.66%,70.26%,21.32%.The conclusion of this thesis illustrates the multi-objective optimization design method proposed in this article,which is optimized for the air conditioning unit pipeline structure.This method can effectively reduce the pipeline vibration displacement,reduce the pipeline vibration stress and reduce the weight of the pipeline.While improving the vibration of the air conditioning pipeline system,the lightweight effect of the pipeline is significant.The research content of this thesis can provide a useful reference for the vibration research of the air conditioning unit piping system and the optimal design of the piping structure.