Research On Thermal Simulation And Optimization Design For Braking Resistor Of Railway Vehicle

Nowadays, regeneration braking has been widely used in rail transportation. Due to the voltage of power grid should not exceed 1800 v, the regenerative braking energy cannot fully feedback back to the grid, and part of the renewable electricity needs to be converted into heat energy and be dissipated by braking resistor. With the continuous improvement of driving speed and traction tonnage, more requirements has been also put forward for braking resistor. When vehicle emergency braking happens, the electric current, by resistance chip, is about 360 amp, and instantaneously, the temperature of resistor has increased dramatically, up to 600 ℃,resulting in resistor deformation occurred. When the deformation is greater than the distance between two pieces of resistors contact, the resistor will be burn out, and have a serious influence on the vehicle driving safety. Thermal simulation for braking resistor and improving the cooling performance of braking resistor is the main content of the project research.In order to make the resistance heat disperse As soon as possible, based on ICEM CFD and CFX software, this paper uses the finite element simulation analysis method for thermal simulation, and braking resistor structure optimization design will be carried on. Resistor flow field analysis model is established, comparing turbulent kinetic energy of the fork row arrangement of flow field with in-line row, to select the arrangement of resistance, in which turbulence effect is better and is conducive to cool the resistor; In braking resistor of Shanghai metro line 9, for example, setting up a parallel resistors thermal- solid- fluid coupling model, combined with the knowledge of heat transfer and fluid dynamics, and considering the effect of temperature on the air thermal physical parameters comprehensively, applying the actual conditions of load and fan air volume to the resistor,carrying on the numerical simulation.The simulation results show that, under the same air flow conditions, the turbulent kinetic energy of the fork row arrangement of flow field effects are better than in-line row, and the fork row arrangement of flow field will effectively improve the heat dissipation performance of resistors, the highest temperature appears in the last row resistor unit, and the highest temperature reached 600 ℃. Having some Related experiments, using infrared sensor to test the highest temperature of resistance and comparing with the simulation results, the feasibility of the theory will be validated by experiment and simulation method; According to the simulation results, By changing the cooling fan power to increase the convective heat transfer coefficient, adjusting the structure of the resistor size to Improve the fluid solid heat coupling effect, choosing other resistance materials, or Reinforcing ribs or notches on the surface of resistance to improve the resistors flow turbulence, optimization design will be carried out on the resistor.A new method of thermal analysis simulation for Rail vehicle braking resistance are studied in this project, and provide theoretical basis for the optimal design of the braking resistor. For the safety operation of the railway vehicles, the project research, this paper puts forward,has important practical significance.