Influence Of Subsurface Structure Of Pantograph Head On Aerodynamic Performance And Noise Characteristics

High-speed train operation is the development trend of rail trains.Under high-speed operation,the air vibrates violently on the surface and behind the pantograph.which will not only generate large force and torque,but also generate aerodynamic noise that cannot be ignored,affecting the flow quality and operation performance of trains.As the key component of the pantograph,the bow head contributes the main aerodynamic force and aerodynamic noise.Therefore,it is of great significance to change the structure of the bow head,improve the aerodynamic characteristics of the bow head,and reduce the aerodynamic noise based on the aerodynamic theory.This paper takes the CX-NG pantograph as the research object,and proposes nine groups of bow heads with saw-tooth structure on the lower surface.Computational fluid dynamics software Fluent was used to simulate the aerodynamic characteristics of bow heads with different structures.Based on the simulation results,the influence of two parameters,the number of saw teeth and the height of saw teeth on the aerodynamic characteristics of bow heads were explored.The principle of drag reduction and noise reduction of saw tooth structure is expounded based on aerodynamics.In the part of flow simulation calculation,in order to ensure the accuracy of numerical calculation method,Two flow simulation examples of cylindrical square and cylinder are established and verified,and the simulation results are in good agreement with the experimental data in the literature.The Transition SST turbulence model was used to numerically simulate the original rectangular bow and saw-tooth bow,and the key data such as pressure,velocity nephogram and aerodynamic force around the bow are obtained.The influence of saw-tooth structure on the flow field was comprehensively analyzed.By comparing the simulation results of each bow head,it is concluded that 5w3 h bow head can effectively suppress wake vortex turbulence separation and reduce aerodynamic drag coefficient.Compared with rectangular bow head at 250 km / h,300 km / h and 350 km / h,the aerodynamic drag is reduced by 8.6 %,8.7 % and 9.9 % respectively.In the aerodynamic noise simulation calculation part,After verifying the accuracy of the numerical method through the aerodynamic noise example.the sound pressure level of rectangular and 5w3 h bow head acoustic measuring points are calculated.The maximum noise reduction of 3.1 d B,4.3 d B and 0.9 d B at each speed indicates that the aerodynamic noise is reduced by optimizing the aerodynamic characteristics of the bow head.Finally,the three-dimensional model of rectangular and 5w3 h bow head is established by CATIA,the simulation results of aerodynamic characteristics and aerodynamic noise of bow head under three-dimensional conditions are analyzed emphatically,which can simulate the actual operation state of bow head more realistically.The simulation results of aerodynamic characteristics and aerodynamic noise of 3D bow head are consistent with those of 2D bow head.5w3 h bow head aerodynamic resistance under different speed conditions were reduced by7.4 %,5.8 %,6.8 %;the maximum reduction of aerodynamic noise amplitude at each measuring point is 12.4 dB,6.7 dB and 5.9 dB.