Simulation Of The Diffusion And Control Of The Urban Bus Indoor Biological Contaminants Based On DPM

Urban bus is the main means of transportation for the people’stravelling, it’s internal flow field quality and pollutant diffusion control iscrucial to the occupants health. The domestic and overseas relatedresearch information shows that, the average level of pollutants in vehicleis about10times higher than the outside, which may cause variousadverse reactions in human. Meanwhile，the large accumulation ofbiological contaminants will easily lead to the spread of diseases. It willlead to the serious health crisis if ignoring the air pollution inside the car.This paper reveals the health hazard of the rapid spread of sneezingpollutants by using numerical methods to simulate the diffusion flow ofthe biological pollutants emitted by human activities in an air-conditionedurban bus. Focus on the underlying healthy problem bring by the largediffusion range and the long time retention of the sneezing pollutants, theair-conditioning ventilation improvement has been put forward. It wasproved that the sneezing pollutants’ diffusion has been controlledeffectively, and the potential health risks has been reduced.The main research contents are as follows:1、Simulated the coupling flow between the phases of sneezingpollutants and the air by using the Euler-Lagrange method based on theDPM（Disperse Phase Model）, At the same time, Realizable k-ε model isused to simulate the urban bus internal air flow and coupling the spacingpressure-velocity calculation by the Pressure-Implict with Splitting ofOperators（PISO) method，witch has a correction process. A numericalsimulation scheme is established for the urban bus interior biologicalcontaminants’ diffusion and validated by an relevant experiment from thereference paper.2、The simulations of the approximate conditions about the speaking,coughing and sneezing activities proves that the propagation distance ofbiological pollutants sneezing activities generated and spread fastest,what’s more, the diffusion range is the largest and the potential healthhazards is the most serious.3、Simulated the diffusion of the biological pollutants produced bypassenger sneezing activities， which has been created at different positions of a certain type air conditioning urban bus. Analyzed theconcentration distribution characteristics of the interior sneezingpollutants and the regional regular diffusion pattern.Then put out a busair-conditioning air supply and return type improvement scheme.4、According to the interior flow characteristics and occupant seatsarrangement，based on the former improving air supply and return type, apersonalized settings of the air-conditioning vents position and blowingangle is conducted, besides that, some suggestions on the air speed settingis proposed.5、Take the instantaneous concentration, cumulative concentrationand retention time as the health risk assessment indexes to evaluate thesneezing pollutants diffusion controlling effect of the air-conditioningurban bus improvement shemes. The evaluation results show that thesneezing pollutants’ diffusion range reduced greatly, the suspensionconcentration decreased significantly and the retention time decreasesobviously.6、On the basis of bus interior environmental health risk assessmentresults，take a regional health risk rating on the urban bus and give thesuggestions about the suspected pathogenic settlement for the emergencycase of experienced respiratory infection.