| Resource deficiency and environment pollution have become issue s that many nations across the world devote to settl e.Lightweight and energy saving technology have become the imperative tendency of the development of rail transportation equipment manufacturing industry.Fan system is one of the important core component to ensure the safe operation of rail transit trains.This paper took lightweight and aerodynamic performance of fan system on the rail locomotives as the research object.It studied the structure and aerodynamic performance of the fan systematically and deeply for the lightweight design as well as aerodynamic performance enhancement problems.The main research work in this dissertation is as following:(1)According to the unsteady fluid-solid interaction technique,the analysis model of fan system performance and impeller structure dynamics were established,which were verified with the aerodynamic performance and strength vibration test of the fan.A reliable calculation model was provided for the lightweight and aerodynamic uncertainty optimal design of the impeller structure.Based on the sensitivity analysis of single and mutilple factors,th e efficiency of the fan was improved by adjusting design parameters,which laid a solid foundation for the study of fan performance optimization.(2)For the lightweight design of the impeller structure,in order to meet the requirement of high reliability of rail transit train equipment,the deterministic,reliability and robust optimization were respectively been studied for the cast aluminum impeller.By comparision,robust optimization is found to have a better uncertainty toleration which can meet the requirements of the application of high reliability and lightweight of locomotive.The weight of the aluminum impeller is reduced by 31% by optimization.Moreover,a sheet molding compound(SMC)impeller technical scheme and inorganic ceramic water treatment technology w ere studied,which can meet the requirements of harsh environment of rail transportation.The weight of the impeller was greatly reduced by the multi-objective robust optimization,which effectively improved the mechanical properties of the fan.Finally,the calculation results were verified by the static and dynamic stress and the over speedtest system,the numerical results agreed well with experimental data.(3)For the lightweigh design of the duct structure,the calculation for the random vibration nonlinear analysis of casing would cost too much time because of the large number of grids.In order to improve the efficiency and precision of robust optimization,an error compensation model between the fine mesh model and a coarse grid model was establish.Through the optimization design of metal casing,the casing weight decreased by 13.4%.A casing structure made of reinforced carbon fiber glass composite material was studied.Through multi-objective robust optimization design,the scheme can meet the fan structure lightweight design requirements better.The test verified that the scheme can satisfy the random vibration and shock test of the equipment of rail transit locomotives after optimazation.(4)Corrosion is one of the most important study content in the fan structure.According to the uncertainty and self-dependence of structure size,material and load,the time-dependent reliability problem is converted to the traditional static reliability.The analysis efficiency of the time-dependent reliability for fan structure is greatly improved by introducing the time discretization of stochastic processes,which can effectively solve the problem of time-dependent reliability of fan structure,such as attenuation and corrosion.The time-dependent reliability analysis of cast aluminum and SMC impeller were carried out for the metal and reinforced fiber casing.All the results meet the requirements of engineering design reliability index,which can provide reference for practical engineering application.(5)For the insufficient samples and information of engineering problems,an uncertain interval optimization design for aerodynamic performance of fan wing based on robustness design was studied.Through establishing the reliability index of interval variables,a robust optimization model was constructed basis on the mathematical model of Kriging approximate function.The dual optimization method was used to solve the optimization problem in order to improv e optimization efficiency.In order to improve the fitting precision of the leaf shape modeling,five polynomial methods were applied to establish the parameters of the airfoil model.The problem of insufficient sample data of fan blade parameters was solved effectively,and the results show that the method could meet the requirement of accuracy of fan performance.This study can provide some new ways for the fan structure lightweight design and aerodynamic performance optimization,which laid a foundation for the lightweight design of rail traffic fan system and energy-saving emission reduction market.Especially,the researches and achievements have very important reference value to other types of rotating machinery. |
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