Numerical Simulation Research On Fire Characteristics Of A Pure Electric Bus

With the vigorous promotion of urban new energy public transportation,the market share of pure electric buses is increasing.The position of the power battery on a pure electric bus is changeable,and once the battery module ignites spontaneously,the flame spreads extremely fast,and it is easy to release poisonous gas,and easy to reignite and hard to completely extinguish,which will result in the lives and property losses of the occupants,and trigger public opinion on the safety of pure electric vehicles with inquiry.Therefore,pure electric buses have higher requirements for fire safety,and it is of great significance to study and analyze their fire characteristics.This thesis takes a Xi’an pure electric bus as the simulation target,and combines the internal material combustion test and FDS(Fire Dynamics Simulator)numerical simulation to analyze and research the combustion characteristics and development law of the situation when a fire occurs in the pure electric bus.Firstly,the four combustible materials inside the bus were burned through the application of a cone calorimeter to obtain the combustion characteristic parameters of the materials.The materials were analyzed from the aspects of ignition risk,heat release rate,smoke toxicity,etc.Then the cone calorimeter combustion chamber was modeled by FDS,and a parameter calculation method for simulating the combustion of composite materials was used for numerical simulation.After comparing with the test results,the simulation results are similar with the test data,which shows the practicability of the parameter calculation method and the dependability of FDS simulation.Secondly,based on the actual structure of the bus and the geometric dimensions and physical parameters of the parts,the modeling part was reasonably simplified.The setting ways of measuring points and survey surface layout,fire source combustion type,grid size and calculation area division are studied,and with the combustion test parameters of the cone calorimeter used as the data basis,the combustion model of the interior materials of the car is set up.A numerical simulation model of pure electric bus fire based on FDS is established.Finally,a total of 22 groups of fire conditions were set up in four categories: typical working conditions,different door and window opening working conditions,different fire source factors working conditions and different environmental wind working conditions.Through curves,contours,2D cut planes and other views,various working conditions are discussed and analyzed from the aspects of heat release rate,average temperature,gas component concentration,smoke spread and movement in the compartment,and the numerical simulation results are summarized.The combustion characteristics and development law of the bus in the event of a fire under different influencing factors are obtained.The research process and conclusions of this thesis can provide references for the safety design,fire prevention and control of pure electric buses and other further researches.