【作者】 郝静；

【导师】 高国强；

【作者基本信息】 西南交通大学 ， 电气工程（专业学位）， 2017， 硕士

【摘要】 弓网系统作为列车重要的取流设备,其良好的服役性是保障列车安全运行的重要条件。目前,弓网关系已作为高速铁路三大关系之一进行深入研究。在列车运行过程中由于升降弓操作、车体振动、接触网导线不平顺和轨道不平顺等因素致使弓网电弧现象频发。一方面电弧燃弧和熄灭产生的电磁谐波和过电压将会给车载电气设备和列车安全运行带来潜在的威胁;另一方面其产生的高温烧蚀接触网导线和受电弓滑板材料,严重影响弓网系统使用寿命。因此,有必要对弓网电弧的物理电气特性及其对受电弓滑板与接触网导线材料的烧蚀特性进行研究。由于现场实验难度大,早期对弓网电弧的研究主要通过模拟实验的方式进行。这些实验对我们理解电弧燃弧、发展及熄弧过程的特性具有很大帮助。然而,由于电弧影响因素复杂、随机性大且测试手段有限,实验方式难以获得电弧演变过程中电弧内部参数随时间的变化规律及其对电极材料的侵蚀规律。因此,本文利用数值仿真技术对受电弓降弓过程电弧动态特性及电弧对弓网材料的侵蚀特性进行研究。本文针对受电弓降弓过程电弧动态特性的研究,以磁流体动力学(MHD)理论为基础,配合动态网格技术,建立弓网电弧动态模型。对商业流体软件Fluent进行二次开发,并将其作为求解平台,对模型进行求解。仿真计算了在受电弓降弓过程中电弧温度场和气流场分布,分析了弓网电弧形态及温度分布动态演化特性,揭示了弓网电弧温度场与气流场相互作用机理。仿真研究了不同降弓速度及输入电流对电弧动态特性的影响。基于弓网模拟试验平台,测得弓网电弧辐射光谱,利用Boltzman测温法推算出电弧燃弧温度,将实验值与仿真值对比,验证模型可靠性。在弓网电弧模型的基础上,以电弧对电极的热传导理论为基础,建立了弓网电弧对弓网材料侵蚀模型。在电极能量方程中引入熔化/凝固模型,求解弓网材料在电弧作用下受热熔化过程。计算分析了热流密度在接触网导线和受电弓滑板表面的分布情况。仿真分析了电弧作用下,受电弓滑板与接触网导线温度分布及其表面形成的熔池深度与半径随时间的变化规律。研究了电流大小对表面熔池半径及深度的影响规律。通过开展弓网电弧对受电弓滑板的侵蚀实验,验证了模型的正确性。更多还原

【Abstract】 The pantograph-catenary(PC)system plays a key role in the electric energy acquisition for high-speed train.Status of pantograph-catenary systems is critically important for working security and reliability.At present,the relationship between pantograph and catenary has become one of three crucial relationships for high-speed railway.Multiple factors will result in PC arc,such as the operation of pantograph rising and lowering,locomotive body vibration,track irregularity,ice coating on the contact line in the cold environment,etc.On the one hand,electrical electromagnetic harmonic and overvoltage due to the arc ignition and extinguishment will throw great potential threaten on the electrical equipment and the secure operation of train.On the other hand,the intensive heat released from arc will induce severe damage on both pantograph strip and overhead contact line material,resulting in an obvious decrease of work life.Therefore,it is necessary to do researches on the characteristics of pantograph-catenary arc.Because of the high risks as well as great difficulties in field experimental measurements,early studies on the pantograph-catenary arc were mainly accomplished by laboratory simulation experiments.Those experiments are helpful for comprehending the basic electrical parameters during the processes of arc ignition,evolution and extinguishment.Because of the transient variation and relative randomness of arc plasma,as well as the complicated factors that influence the properties of arc plasmas,it is hard to obtain the details of the arc plasmas themselves,with regard to the space-time evolution of internal parameters,and the erosive effect of it on electrodes.Therefore,the numerical simulation was used to study the dynamics of PC arc during pantograph lowering process and the erosive effect of PC arc on the materials of PC system.This paper focused on the dynamic characteristics of pantograph-catenary arc during the pantograph lowering process.A dynamic pantograph-catenary arc model was established based on the classical magneto-hydrodynamics(MHD)theory,with the temporal evolution of PC arc dynamics taken into account.And the dynamic mesh technique was utilized to take care of the departure process between the pantograph and catenary.The model was calculated by a modified commercial fluid code Fluent.The temperature and flow fields during pantograph lowering were calculated.The evolutions of shapes and temperature distributions of PC arc were analyzed.The interactions between temperature fields and flow fields were elaborated.The effects of pantograph lowering speed and input current were studied.The emission spectrum of PC arc plasma was measured based on the PC arc test device.The Boltzman method was used to caculated the average temperature of arc plasma.The result from simulation was compared with that from experiments in order to validate the model.Based on the magneto-hydrodynamics(MHD)theories and the heat conduction theories from arc to electrodes,a model of coupled pantograph-catenary arc and electrodes was established.The melting and solidification model was added to the energy conservation equation to calculate the melting process of electrodes under the effect of arc.The distributions of heat flux on the pantograph and catenary surface were calculated.The temperature distributions and the depth of melting pool,as well as the radius of melting pool on the pantograph and catenary over time were simulated.The effect of current on the size of melting pool was analyzed.The experiments about the erosive effect of PC arc on the pantograph was carried out to validate the model.更多还原