紧急制动工况下电磁式磁轨制动器极靴磨损计算方法

为了预测极靴服务寿命, 确保制动可靠, 通过磨损过程、制动过程、制动器/钢轨温度场的建模与仿真, 计算了高速列车紧急制动过程中电磁式磁轨制动器极靴磨损量; 建立了考虑速度与温度的Archard磨损模型和CRH2列车紧急制动过程的动力学模型, 计算了电磁式磁轨制动器样机全程参与制动时的空气制动力、电磁制动力、制动减速度、紧急制动能量分配系数、瞬时速度和制动距离等时变参数; 分析了紧急制动时电磁式磁轨制动器-钢轨-大气间的热量传递, 基于Fluent软件建立了制动器/钢轨的三维温度场模型, 根据制动过程时变参数获取温度场热流密度和散热加载条件; 针对CRH2列车行驶速度为250km·h^-1的紧急制动工况, 计算了制动器极靴的磨损量。计算结果表明: 在制动过程中, 钢轨顶部温度随着与制动器的接触状态变化呈波动变化, 在距离有效制动起点1 620m处, 钢轨与8号电磁式磁轨制动器接触结束时, 温度达到最大值570.76℃; CRH2列车同侧8个制动器极靴底部在制动时间为24.5s时温度达到最大值, 从前到后依次为1 022.6℃、1 037.7℃、1 045.3℃、1 052.8℃、1 085.7℃、1 100.9℃、1 109.2℃、1 124.4℃, 极靴磨损量从前到后依次为207.4、208.7、210.0、210.7、212.1、213.4、214.4、215.5g。可见, 制动器工作会使钢轨产生热量积累, 导致列车运行方向后面的电磁式磁轨制动器极靴温度较高, 磨损量较大。

Pole shoe abrasion calculation method of electromagnetic track brake under emergency braking condition

To predict the service lives of pole shoes and ensure brake reliability, the pole shoe abrasion losses of electromagnetic track brakes (ETBs) during emergency brake of high-speed train were calculated through modeling and simulation of abrasion process, braking process and temperature field of brakes and rail.The Archard abrasion model considering speed and temperature and the dynamics model for emergency braking process of CRH2 train were built.Time-varying parameters including air braking force, electromagnetic braking force, brakingdeceleration, energy distribution coefficient of emergency braking, instantaneous speed and braking distance were calculated during the process of test ETBs'whole-process works.The heat transfer among ETBs, rail and atmosphere during emergency brake was analyzed, a 3D temperature field model of brakes and rail was established by using Fluent software.The heat flux of temperature field and the heat dissipation loading condition were obtained according to the time-varying parameters during braking process.The pole shoe abrasion losses of brakes were calculated during emergency braking process of CRH2 train with the running speed of 250km·h-1.Calculation result shows that the temperature of rail top displays fluctuation changes according to the contact conditions between brakes and rail.The maximum temperature reaches 570.76 ℃in the spot with 1 620 mfrom brake start when the contact between rail and No.8ETB ends.When the active braking time is 24.5s, the maximum temperatures of pole shoes bottoms of those same-side eight ETBs in CRH2 train are 1 022.6℃, 1 037.7℃, 1 045.3, 1 052.8℃, 1 085.7℃, 1 100.9 ℃, 1 109.2 ℃, 1 124.4 ℃in order from front to rear, and the abrasion losses of ETBs pole shoes are 207.4, 208.7, 210.0, 210.7, 212.1, 213.4, 214.4, 215.5g.So, the heat accumulation of rail generates during working process of brakes, which will lead to the higher temperature and larger abrasion losses of latter ETBs'pole shoes in train running direction.