| The cabin of the aircraft is closed,narrow and crowded.If there are sick people among the passengers,the respiratory droplets containing pathogens exhaled by them will pose a greater threat to the health of other passengers.Therefore,it is of great significance to study the propagation law of pathogen droplets in the cabin and the concentration distribution of pathogens in the cabin to improve the cabin environment and ensure the safety of civil aviation transportation.This paper takes the B737 NG cabin as the research object,firstly establishes the simulation model of the flow field in the cabin,divides it with regular tetrahedral meshes,and refines the meshes of the air outlet and other parts.Boundary conditions such as intake and exhaust,wall surface,and temperature are set,and the Realizable k-ε model is used to simulate and solve the steady-state turbulent motion in the cabin,and the airflow velocity distribution,pressure distribution and temperature distribution in the cabin are obtained.The actual velocity distribution of the air flow field was measured by the PIV method under the similar shape of the experimental cabin and the same boundary conditions.By comparing and analyzing the simulation data and experimental data of the internal flow field,the two have the same flow field organization,and the middle downwash airflow divides the entire cabin cross-section into two turbulent vortices with relatively symmetrical left and right;At the same position,the maximum percentage deviation of the two speeds is 6.25%.On the basis of the internal flow field,the UDF was used to optimize the droplet exhalation velocity when the patient coughed,and then the DPM model was used to numerically simulate the spread of pathogen droplets in the passenger cabin when the passengers coughed and sneezed.Under the condition of high wind speed(5m/s)for air supply on the side walls and ceiling,the propagation and diffusion process of droplets produced by coughing in the passenger cabin was analyzed,and it was found that due to the influence of two turbulent eddies in the inner flow field,the main It spreads on the side of the sick passenger;before the droplets are discharged from the passenger cabin,most of the longitudinal propagation distance is within2 rows;the number of droplets that spread upward is greater than the number that deposits downward,showing a trend of upward spreading in general.By changing the air supply mode and air supply speed,the air supply volume of the individual air outlet,and the position of the sick passenger,the influence of these factors on the spread of cough and sneeze droplets was analyzed.The research results show that the droplet diffusion concentration decreases more slowly when the ceiling air supply and side wall air supply is compared with the ceiling air supply,but the decreasing trend of the two is the same.However,it will accelerate the diffusion speed and shorten the transmission time;the concentration of each row of sneeze at each moment is higher than that of cough,the concentration in the passenger cabin decreases faster,and the diffusion time is longer.By analyzing the position of the maximum jet velocity in the longitudinal section of the passenger cabin,the moving direction of the jet after convergence and the distribution of the airflow velocity in the passenger cabin,it is concluded that the liquid droplets have a forward propagation trend in the passenger cabin.Based on the number of pathogen droplet particles at each location,the Wells-Riley model was used to predict the infection probability of healthy passengers.Changing the position of sick passengers and changing the amount of ventilation in the cabin found the seating position with the least risk of infection for healthy passengers. |
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