The bow net arc and thermal radiation injury to the catenary
The bow net arc ablation catenary wire and pantograph skateboards, their level of ablation and closely related to the size of the bow net arc energy, in addition to the research on the size of the bow net arc energy arc's influence on the pantograph slide and wire wear also has a vital role.
Through the experiment analyzes the different C/C composites under the bow net arc energy skateboard wear condition, with the increase of arc energy, material wear mechanism changes, also under the lower arc energy, material wear mechanism is mainly abrasive wear, under high energy arc, arc of instant high temperature makes the deposition of carbon and carbon fiber evaporate gasification, hollow, material wear mechanism is mainly for the electrical wear.
Voltage, current, and the contact breaking speed on the relationship between the dc arc energy, the increase of voltage grade will largely improve the arc arc time and arc energy, arc energy increases with current rise.Arc energy affect the bow net arc, the distribution of temperature field in the arc under the action of high temperature, lead to serious wear and tear, skateboarding and contact line and the bow net arc energy in addition to related to the discharge time, discharge power, also related to the bow net arc in high speed air flow field.
Arc plasma thermal field, flow field and electromagnetic field exist in the complicated process, mutual coupling between each field through some related parameters.Thermal field and flow field of the basic parameters as temperature, pressure and velocity, the change of temperature and pressure will cause arc gas viscosity coefficient, electrical conductivity, radiation absorption coefficient in the physical parameters such as change.Arc thermal field and electric field mainly mutual coupling by joule heat and electrical conductivity, electrical conductivity change makes the electric field of electric arc and current distribution changes, thus cause the change of the magnetic field.
Current density will produce joule heat of unit volume, it is a gas arc heat source, as a source term directly involved in the calculation of arc energy equation.Magnetic field caused by the lorentz force on the gas flow in arc, and as a body force directly involved in the calculation of momentum equation, thus realized the coupling of magnetic field and flow field.The calculation of thermal field needs to consider the role of conduction, convection and radiation, among them, the radiation heat is one of the important source term in the arc heat field equations, its size is related to temperature and radiation absorption coefficient.
Thermal radiation is in the hot, including the bow net arc plasma is an important phenomenon and the research content.Arc thermal radiation refers to the high temperature, by disturbance of atoms, the vibration of the electronics and stimulated to emit light, the wavelength in the spectrum of colours for the range of 0.4 ~ 40.0 mu m after the projected onto the object can be absorbed, into the process of thermal energy.
Thermal radiation is energy by means of electromagnetic wave propagation, it does not require direct contact between the objects.Thermal radiation embodied in: (1) arc higher temperature region, radiation is the main form of energy dissipation;(2) the radiation heat transfer is a kind of effective energy within the plasma exchange way;(3) plasma radiation out energy can heat the surrounding gas or erosion of the external material.The center of the arc heat energy outward radiation, low temperature area for part of the edge energy imbibition phenomenon exists.