Study On Aerodynamic And Noise Characteristics Of Bow Head Of High-speed Train Subjected To Crossbow

Accompanied by the continuous improvement of high-speed train operation speed,its aerodynamic and noise problems have become increasingly serious.When the train speed exceeds 200km/h,approximately 70% of the power is used to overcome air resistance.The pantograph is installed on the top of the train,and the pantograph head is the main source of the air resistance of the whole pantograph.Its aerodynamic characteristics are important factors affecting the current collection quality and aerodynamic noise of high-speed trains.As result,considering the influence of aerodynamics on the pantograph,it is of great significance for the development of high-speed pantograph to carry out the optimization of pantograph shape structure and aerodynamics.In this paper,the pantograph head of high-speed train is taken as the research object,and the fluid mechanics calculation software fluent is used to model the aerodynamic characteristics of the pantograph head;The structure of pantograph head is optimized,and three new types of pantograph head structures,namely,long curve,long triangle and wavy bottom surface,are proposed;At the same time,the influence of bow head structure on aerodynamic characteristics was explored to achieve drag and noise reduction effects.At first,in order to verify the accuracy of the turbulence model,the flow around cylindrical and square columns was studied for model validation.The numerical simulation results were in good agreement with previous literature simulation results,indicating that the Transition SST turbulence model can be used for numerical simulation of the two-dimensional model of the bow head.Then,based on CX-NG pantograph,the traditional square pantograph model is established and simulated.Secondly,the surface structure of its pantograph head was redesigned,and its shape was optimized to three new types of bow heads,namely,long curve,long triangle and wavy bottom surface.Fluent was used to conduct numerical simulation analysis on the aerodynamic characteristics of the bow head at different speeds,study the variation laws of flow field cloud,pressure cloud and aerodynamic characteristics at different speeds,and compare the aerodynamic characteristics of the optimized bow head with the traditional square bow head,Analyze the influence of different external structures on the formation and suppression of tail vortices behind the bow head.Through comparative analysis,it is found that the best drag reduction effect can be achieved by using the long curve pantograph head.Finally,the three-dimensional model structure of the long curve pantograph and the original rectangular pantograph is established.The aerodynamic characteristics and aerodynamic noise characteristics of the long curve pantograph and the rectangular pantograph are numerically simulated.At the same time,their dynamic characteristics and aerodynamic noise characteristics are compared.The results show that the use of long curved pantograph has a certain effect of drag reduction and noise reduction,which is due to the fluid flowing through the curved surface,effectively reducing the shedding of the wake vortex,and greatly reducing the aerodynamic drag.When the train speed is 350 km/h,the noise in three directions of the pantograph is reduced by 7.372 d B at the highest level,which indicates that the long curve bow head has good aerodynamic characteristics and can effectively reduce aerodynamic noise.