Study Of The Influence Of Haze Weather Conditions On The Particulate Matter Value In High-speed Train Carriages

With the rapid development of high-speed railway,the increase of speed brings kinds of advantages to railway,and at the same time,it also makes some problems that easy to be ignored in low speed become prominent,air environment is one of them.Carriage air environment comfort mainly includes pressure change,air velocity,temperature,humidity,air components(including various chemical gases and particulate matter),noise and so on.In recent years,with the improvement of people's living standard,the influence of particulate matter on human health has been paid more and more attention,the study of particulate matter in the field of high speed trains is relatively less.The fresh air inlet of the train air conditioning system communicates with the external environment,when the external air contains a lot of particles,these particles may enter the carriage through the fresh air inlet of the train air conditioning system,causing carriage air pollution.Particles that affect the comfort of passengers mainly refer to the PM10 and the fine particles PM2.5 which are more harmful to the human body.This paper considers the external flow field and the internal flow field(composed of ventilation pipe with filter and carriage)of high speed train,use a three-dimensional coupling numerical simulation to calculate carriage PM value in different external environment,considering the installation of different grade filter.Finally compare the carriage PM value with the national standard,give the evaluation of vehicle pollution situation,and provide a reference for the high speed train carriage particulate pollution problem.The main conclusions of this paper are:with the high-speed train's running,will appear the particles concentration phenomenon around the train body.The concentration of particles occurs mainly in the head,the bogies at the bottom of the train and the vicinity of the air conditioner.As the speed increases,the concentration of particles in the fresh air inlet increases first and then decreases,reaching the maximum at about 180km/h.Under the R-R particle size distribution,the mass flow of particles at the fresh air inlet increases first and then decreases with the increase of the speed,and reaches the maximum at about 180km/h.When the particle size distribution is single particle size,mass flow of small size particles in the frsh air inlet with the increase of speed showed the increase to decrease trend,the smaller the particle size,the increasing trend is more obvious,the greater the increase in proportion;large size particles in the the fresh air inlet decreases monotonously with the increase of speed,with the particle size increases,mass flow decreased faster.Without a filter,carriage PM10 and PM2.5 value have exceed the standard.G2 and G4 grade filters can make the carriage PM10 and PM2.5 value meet the 24h limit specified by the national standard when the air quality grade is first and two,and G2 filter has higher cost performance.F6 grade filter has best filtering effect,which can make carriage PM2.5 value reached 24h limit requirements when air quality in grade three,so it can cope with severe weather pollution.At the same time,we should choose the high speed train air conditioning filter reasonable to save the resources according to the change of the particle middle size in different areas.