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Study on Pollution of Air and Cleaness Measurement of Air Inside Automotive Function Examination Works

Author: ChenWenJuan
Tutor: SuJian
School: Jilin University
Course: Vehicle Operation Engineering
Keywords: Automotive function examination works The measurement of protecting air cleaness Air pollution box mode FLUENT simulation
CLC: X51
Type: Master's thesis
Year: 2005
Downloads: 236
Quote: 5
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Abstract

Because our country establishes maintenance policy about the using car,it is“Periodical Examination,Compulsive maintenance and Considering fix”,therecomes many automobile function testing station of different classes in everylocality.Espicially in the Automobile all Functions testing station,it includes manyexamination itemes,for example,automobile safety,automobile motive,automobileeconomic etc.And some of examination itemes are completed through imitatingdriving appearance on the pedestal in room ,so the waste gas quantity that carexhausts is large.If the well ventilated condition in indoors is poor, waste gas willwidespread indoors,so examination works is polluted ,at the same time workers aresuffering the health endangers.So far ,any scholars haven’t maded the research of waste gas pollutioncondition and Well ventilated measures in examination works,through checkingthe data,several aspects of this problem will be studied in this paper.1. The theories foundation of the air pollutionFrom one of characteristics that atmosphere boundary layer,s pollution: theatmosphere resemblly is regarded as a kind of glue uncompressable air ,we knowthat atmosphere movement first satisfies a set of basic fluidequations—Navier-Stokes equation.And from the second characteristic ofAtmosphere boundary layer,s pollution: swift flow of fluid, three kinds of basictheorieses about swift flow proliferation—the swift flow steps degree transportstheories, swift flow statisticses theories and resemble theories are described one byone.But it isn,t enough that directly appling the basic theories to estimate airpollutant density distributes and its variety of spacetime, concrete term factors suchas contaminative space,weather factor and characteristics of polluting source mustbe considered.2. An air pollution density mode inside examination worksEnvironment of examination works relatively is a small closing space,thecharacteristic of polluting source indoors is line source which is constituted by carwaste gas,the entrance and exit of works are influenced by Wind velocity withdirection of wind.From above limit condition ,a box mode theory is introduced inthe paper. Abroad scholars put forward making use of mathematics mode to deduce theindoors air pollution density in middle of 70’s of last century,as a result, indoors airpollution influence factor mode is deduced from the equilibrium theories inquantity researched abroad: Ci =(S + Co ? a) (a + D),(the mode includes outdoorsair quantity Co , indoors pollution source S,polluting material reduced rate D,airexchanged rate a ,etc factors). After analysising the dynamics process of the airpollution in detail,it is : The current of air inside the examination works is primarilyinfluenced by the convection breeze,the influence that the density of pollutantsource is small through fluxing proliferation function with the surrounding air,andthe construction of works’absorbing and solving function to the pollutant inside theworks is weak, pollutant density influencing factors is simply induced as airexchanged rate a and deduce a mode of air pollution density in examinationworks is Ci = Co + S a . 3. The numerical simulation of an air pollution condition insidethe examination works With the development of computer technique and the technique of the swiftflow imitated, the estimating method that making use of the computer to solve theindoors air current and air organization distribute controlled equation sets( Numerical Simulation) ,it is Computational Fluid Dynamic(CFD) that hasdeveloped a lot. The CFD has special advantages such as the low cost , the quickspeed , the complete data and it also can imitate various different work conditionetc. many domestic and international scholars did many works in the CFD, havedevelopped some software, The software of Fluent is an early internationaldeveloped software of CFD, its function is stronger and bigger, application is morewide. This paper makes use of the FLUENT fluid calculation software to imitate aheavy type car which is examined at the car,s bedrock measured machine inworks.after getting the result imitated of a few typical space positions to analyzecharacteristics of air current and pollutant,to get the relation of air pollutiondensities with wind velocity and direction of wind inside the examination works. 4. the spot observation experiment inside the examination works The spot observation experiment is also extremely important research means,because it can provide changing data observed physically which includes thepollution condition of the environment or the examination result of the air quantitywith the data of simultaneous weather,s changes. I choosed the CO pollutant as the measured material at the process ofexperiment, adopted the carbon monoxide measured instrument to measure densityvalue and Choosed to use the wind velocity and direction of wind instrument ofpropeller three cup type to measure the size of the wind velocity with the directionof wind, after the spot experiment of several days and analysising the datameasured physically,the relation of waste gas pollution inside examination workswith car rate, vehicle type, contents of item examinated and the variety of windvelocity ,etc has been concluded ,it is as following : 1. The relation of pollutant average density in indoors with the car rate is theline form. 2. In the partial space,for example,ditch 、nearby the break power measuredset 、Speed measured set 、car,s bedrock measure machine,there is moment seriouspollution,the moment pollutant density is related with vehicle type(the deal of abicycle exhausts) 、the time that a vehicle stays at somewhere 、working conditionof vehicle and the direction that the tail windpipe exhausts. 3. If the wind is high and the direction of wind is the same with the facing ofworks , a burst of strong convection breeze is in works under the condition thatopening the doors of works .even so, a high pollution density will be still exsitssomewhere inside the works for short time, air pollutant density distributes insideworks is related with the wind velocity and direction of wind. Have passed several days experiment,we have simple quantity cognition

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