| The stable contact of bow net system has always been an important technical problem in the development of high-speed railway.The stable contact of pantograph-catenary limits the breakthrough of high-speed train speed.The catenary provides continuous power for the train and also provides a stable sliding channel for pantograph.Improve the quality of the pantograph,to ensure the safe operation of high-speed train,bow net system are closely related in electrical and mechanical,so the pantograph-contact wire as a link between railway power system and high speed train,the study of the bow net system,bow net system is mainly by the contact force,train speed,diversion current size,these factors through force field,speed field,electric field field physical coupling of bow net temperature field plays a different degree of influence.In this paper,the heat-electric-force-magnetic multiple physical field coupling under the action of pantograph and contact wire system temperature field made numerical simulation study,studied the transverse reciprocating motion,fluctuation load,different speed,different contact force and different current under different conditions of bow net system temperature field changes,and bow net system respectively in single friction heat,single resistance heat and two kinds of heat source coupling temperature field change,the variation of the high temperature with time under the effect of multiple physical fields is analyzed.Using the finite element simulation of COMSOL software,we study the influence of mechanical friction heat and arc heat on the bow net system.According to the analysis of the distribution cloud map,it is found that the friction heat of the pantograph contributes less to the temperature rise at high speed,while the resistance heat and arc heat are the main heat sources that cause the temperature change of the bow net,and account for a large proportion.The generation time of arc heat is short,which is easy to cause high temperature on the surface of arch net.By comparing the temperature graph,it is found that under the same contact force,the mean temperature of the pantograph decreases with the increase of the sliding velocity v,while the transient mean temperature of the pantograph and the wire increases with the increase of the current I.(1)The study shows that when the pantograph is reciprocating horizontally,the surface of the skateboard can be evenly heated by the heat source.When working,the heat source will move on the whole surface of the skateboard,leading in the scattered temperature field of the skateboard.The periodic fluctuation load produces fluctuation changes in the temperature field of the pantograph.However,the mean temperature has a larger range under the static load,but the temperature difference between the fluctuation load and the static load is only between 2 and 4K,indicating that the fluctuation load has less influence on the temperature field of the pantograph.This paper studies the change of the temperature field of the pantograph has the largest convection coefficient under the deviation of the surface and the upper surface,and the average temperature difference between the windward surface and the back plane will increase from 0K when there is no coefficient deviation to 2K when the coefficient deviation is 50%.In addition,the position of the highest temperature of the skateboard will also be moved back from the middle area.(2)In only frictional heat action,the skateboard temperature increases with the speed,and the skateboard temperature rises gradually with the speed,and the rising trend is faster.The temperature of the bow net system increases more with the contact force than the velocity.As the speed and pressure increase,the heat absorbed by the wire and the skateboard gradually increases,and the heat absorbed by the wire is always 2.4 times that of the skateboard.(3)Under the simulation study,it is found that when the sliding speed of the pantograph is 320 km/h and the current increases from 0A to 400 A,the temperature rise of the resistance heat is 95.81 K,while the temperature rise of the friction heat is59.55 K.Therefore,the effect of the resistance heat on the skateboard is greater than the friction heat,and the temperature rise is 1.6 times that of the friction heat.Under the friction heat and heat resistance of the heat-electric-force coupling,the average temperature of the skateboard increases by 448.82 K,the temperature of the skateboard increases by 155.52 K,and the temperature of the skateboard decreases slightly with the increase of speed.(4)By studying the changes of friction heat,resistance heat and coupling at different speeds,we find that only when the temperature of the bow net system is low,the temperature difference with the external environment is small,so the heat dissipation is less;with the increase of the speed,the skateboard temperature rises slowly.When there is resistance heat and two heat sources coupling,the temperature of the skateboard is higher,and the temperature difference with the external environment is larger,so the heat dissipation is more,resulting in the gradual decrease of the skateboard temperature with the increase of speed.(5)The offline arc will transiently increase the temperature of the contact surface of the bow net system,and when the offline current exceeds 3000 A,the short high temperature may exceed the melting point of the skateboard,resulting in severe burning of the pantograph and wire.The high temperature generated by arc heat will affect the temperature field of the bow net system,requiring two stages: rapid cooling and slow cooling,requiring a total of 370 seconds to dissipate and dissipate. |
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