Multi-objective Optimization Design Of High-speed Train Nose Profile Based On Aerodynamic Characteristics

With the increasing speed of high-speed trains,the impact of aerodynamic problems becomes more and more important.The aerodynamic drag,the aerodynamic noise of the train aerodynamics characteristics often have inseparable relationship with the shape of the train,to improve the aerodynamic characteristics of high-speed train,based on the aerodynamic drag,the aerodynamic lift and far field with the optimization target of aerodynamic noise high-speed train streamlined head type established multi-objective aerodynamic optimization design process,the high speed train head wake linear geometric shape optimization design.Firstly,the aerodynamics simulation analysis of the front surface of high speed train is carried out.Under the condition of saving calculation cost and ensuring accuracy,a geometric model of three high-speed train assembly was established.Hyper Mesh software was used to establish the calculation domain and mesh the train and the calculation domain.Using Fluent software,the steady state simulation calculation of the pulsating pressure on the surface of the front surface was carried out to analyze the causes of the aerodynamic resistance and aerodynamic noise of the high-speed train.Taking the front surface as the noise source,the sound field processing module was used to analyze the acoustic spectrum of the receiving point of the noise,and the optimization method of the high-speed train head shape was obtained.Then,through the multi-objective optimization design method,a multi-objective optimization design was carried out to reduce drag and noise of the streamlined head of high-speed train,so as to obtain the best streamlined head.Isight integrates Sculptor and Fluent to establish an optimization platform.Sculptor software is used to generate calculation samples of the model.Eight optimization design variables are extracted from the vertical,longitudinal and transverse directions of the train,and a mesh that can be deformed in all directions of the train head car according to the samples is obtained.The DOE sampling module in Isight software was used to obtain the values of 8 optimized design variables by Latin hypercube sampling method.The corresponding samples of all the variables were calculated and analyzed by Fluent software.On this basis,the Kriging approximate model was constructed by Isight to obtain the relationship between the objective function aerodynamic resistance,aerodynamic lift,far-field aerodynamic noise sound pressure level and each independent variable,and the NCGA algorithm was used to find the optimal solution of the approximate model.The optimization results show that the independent variables of the optimization design are coupled with each other and affect the aerodynamic characteristics together.The optimized streamlined head shape can reduce the aerodynamic resistance of the high-speed train by 5.61%,aerodynamic lift by 0.91% and far-field aerodynamic noise by11.89%,which can obtain the head shape of the train with better aerodynamic characteristics.