| In recent years,with the rapid development of the national economy,people's lifestyles have undergone tremendous changes from solving food and clothing problems to pursuing material life.The rapid development of the Internet industry has prompted the rise of e-commerce,changes in shopping methods,and higher and higher requirements for freight transportation.Traditional freight trains have been unable to fully meet the needs of modern freight transportation.Express freight trains,as a new generation of freight vehicles,can meet the transportation needs of some high value-added goods and have a greater market share in the future.When the express freight train passes through the tunnel,the air flow in the tunnel will be restricted by the train surface and the tunnel wall,generating pressure waves.The pressure wave will affect the ear comfort of the passengers and passengers,and will endanger the safety of the operators in the tunnel in serious cases.Due to the faster speed of the express freight train and my country's traditional freight train,it will reach 160km/h.Therefore,the tunnel aerodynamic problems caused by the express freight train running in the tunnel are more serious than the traditional freight train.It is necessary to analyze and study the pressure wave generated when express freight passes through the tunnel.Present work,11-group express freight trains,8-group passenger trains and 1200 m long tunnel are the main research objects.Using CFD software and three-dimensional numerical simulation methods,the Serra express freight train single train passes through the tunnel and the full-side open express freight The single train passing through the tunnel,the Serra express freight train passing through the tunnel at constant speed,and the Serra express freight train and passenger train passing through the tunnel at different speeds in the center are studied.The adopted turbulent flow models are the Reynolds time-average equation and the SST k-? equation.The full-wall processing method is used to solve the relevant working conditions of the express freight train passing through the tunnel.The relative motion process in the simulation model is simulated by the overlapping grid method.Research shows:(1)Whether it is a single train passing through a tunnel or a constant-speed intersection in a freight train tunnel and a non-equal-speed intersection in a passenger and freight train tunnel,the pressure fluctuation outside the train is the result of the combined effect of the train's running trajectory,compression wave and expansion wave.(2)When a single train passes through a tunnel,for the maximum value of the pressure wave of the head car,middle car and tail car,the maximum positive pressure value of the full-side open box car is 23.6%,34.6% and 22.7% larger than the Sierra car.The maximum negative pressure value,the full-side open box car is 18%,13.1% and 15.7% larger than the Sierra box car respectively;The peak-to-peak maximum pressure is 21.3%,19.5% and 16.5% larger than that of the Sierra box car.(3)When two trains pass by each other with different speeds in the center of the tunnel on different lines,the pressure fluctuation of the train body on the passenger and freight line is larger than that on the normal speed line.(4)When two trains pass by each other with different speeds in the center of the tunnel on different lines,the maximum value of the pressure wave of the head car,middle car and tail car is the maximum positive pressure value,which is 10.7%,59.7% and 87.5% larger than the normal speed line on the passenger and freight lines;the maximum negative pressure value,the total passenger and freight line is 20.3%,24.3% and 25.1% greater than the normal speed line;its peak-to-peak,the passenger and freight line is 16.4%,33.9% and greater than the normal speed line respectively 37.1%. |
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