Numerical simulation and optimization on opening angles of aerodynamic braking plates sets for a maglev train

The aerodynamic braking has become an attractive option with the continuous improvement of train speeds.The study aims to obtain the optimal opening angles of multiple sets of braking plates for the maglev train.Therefore,a multi-objective optimization method is adopted to decrease the series interference effect between multiple sets of plates.And the computational fluid dynamics method,based on the 3-D,RANS method and SST k-ωturbulence model,is employed to get the initial and iterative data.Firstly,the aerodynamic drag and lift are analysed,as well as the pressure and velocity distribution of the flow field with the braking plates open at 75°.Then,the aerodynamic forces of each braking plate pre and post optimization are compared.Finally,the correlation between each set of braking plates and the optimized objective is analysed.It is found from the results that the aerodynamic drag and lift of the train have significant differences with or without multiple sets of braking plates.Additionally,the design variable corresponding to the number of iterations of 89 is taken as the rela-tive optimal solution,and its opening angles of braking plates(B2-B5)are 87.41°,87.85°,87.41°,and 89.88°,respectively.The results are expected to provide a reference for the opening angles design scheme for the future engineering application of high-speed maglev train braking technology.

Regularity and sensitivity analysis of main parameters of plate effects on the aerodynamic braking drag of a high-speed train

With increase of train speed,braking plate technology has a good application prospect in the high-speed stage of the train.Based on the 1/8 scaled symmetrical train model composed of two half cars,the Reynolds Av era ge Navier-Stokes(RANS)equations and Shear Stress Transfer(SST)k-ωturbulence model are adopted to simulate the aerodynamic performance of the train with plate.The aer odynamic dra g de pendence of single par ameter of the plate(shape,area,angle,position and n umber)is anal ysed,and identification resear c h of the main aerodynamic parameters of the plate is carried out.The numerical settings used in this paper are verified by wind tunnel test data.Results show that the braking plate with an aspect ratio of one has better performance on aerodynamic drag.The area,opening angle and number of plates are basically positively correlated with the total aerodynamic drag of the target car and plate.Arr anging plates at the downstream of the vehicle is a good method of raising total aerodynamic drag.Within the range of plate parameter design in this paper,by using orthogonal design of experiment and the method of range analysis and analysis of variance,the influence degrees of plate parameters on aer odynamic dra g ar e determined,and the order is n umber,ar ea and opening angle of plate.The research results provide theoretical support for the design and safe operation of high-speed trains with aerodynamic braking plates.