Research On Apray Aerosols Motion Law In Air-conditioning Room

In recent years,the number of people suffering from respiratory infectious diseases is increased by worldwide haze weather,which causes the attention of people to the air quality.With the spray aerosols produced by people speaking,coughing,sneezing and other respiratory behaviour,the viruses move in the air-conditioning room,which pollute the indoor air and threaten to health.This paper uses CFD numerical simulation method to study the trajectory spray aerosols produced by people speaking continuously and a cough,grasps the motion law and distribution of spray aerosols,and seeks the best air-flow organization of air-conditioning room to control the spread of respiratory infectious diseases.This paper builds air-conditioning rooms,including small-office and conference room.Take into account the effect of air speed,the position of the human body and the air-flow organization on spray aerosols trajectory.Compare advantages and applicability of various turbulence models.Choose RNG k-? turbulence model to simulate temperature and velocity fields of air conditioning room.Analyse the force on spray aerosols to establish mathematical model of spray aerosols movement by Euler-Lagrange method.Use SIMPLE algorithm to slove the steady state of spray aerosols produced by people speaking continuously.Use PISO algorithm to slove the unsteady state of spray aerosols produced by people coughing once.The numerical simulation results of different cases are analyzed by velocity vector diagram,temperature contour diagram,non-uniform coefficient,energy utilization coefficient,number of spray aerosols,concentration of spray aerosols and contaminant removal effectiveness.The comparison of simulation results show that with the supply velocity increasing from 2m/s to 4m/s,in wall attachment jet velocity fast decay stage,velocity attenuation range of the wall attachment jet upper part is 2.6 times bigger than the wall attachment jet center and 4.8 times bigger than the wall attachment jet under part.In wall attachment jet velocity slow decay stage,time attenuation range of unit length of the wall attachment jet upper part is 3.6 times longer than the wall attachment jet center and 9.0 times shorter than the wall attachment jet under part.When supply velocity is larger for each 1m/s in up supply-up return air-flow organization of small-office,spray aerosols movement time will be shorter about 6.35%and spray aerosols movement distance will be shorter about 10.58%.The initial velocity direction of spray aerosols initial velocity direction and the position of outlet have influence on spray aerosols trajectory.Making the direction of spray aerosols produced by people near the indoor air flow direction and installing outlet near the pollutant can control the spread of the virus effectively.In two sides supply-up return and up supply-up return air-flow organizations in conference room,the exposed sitting at the middle of conference table and near the window are more susceptible to infection.In the underfloor down supply-up return air-flow organization in conference room,the the exposed sitting near the pollutant and the window are more susceptible to infection.Displacement and underfloor down supply-up return air-flow organizations have the strongest ability to discharge spray aerosols.To sum up,increasing supply velocity reasonably,local ventilating near the people or setting air outlet and using down supply-up return air-flow organization,displacement and underfloor down supply-up return,all can effective control the spread of respiratory diseases and provide people with a healthy and comfortable indoor environment.