The Study Of Relationship Between The Jet Boundary Layers And The Health Of The Ventilation Control Domain

Comfortable and healthy indoor air environment is critical to the human body.The indoor air quality became more and more critical because of the energy crisis,sealed building and inappropriate construction.The trend of ventilation was from cared temperature and humidity of indoor air-conditioning to concerned the air quality.The airflow was not sent into the whole room but directly sent into the the designated region.This improved the effectiveness of air supply.Healthy ventilation gradually became the future trend.Most of the indoor air ventilation is jet flow.We use the jet air to control the spread of the harmful pollutants.The studies of the distribution of jet boundary layers,especially the relationship and thickness between the boundary layers have great significance.We can use this theory to control the pollutants and determine the domain of health ventilation.In our study,we use the theoretical of jet and CFD numerical simulation two methods. The effects factors of laminar and turbulent jet boundary layers' thickness were discussed.At the meantime we analysis the laminar,turbulent diffusion coefficient and obtained the laminar(turbulent) flow jet's velocity,temperature and concentration boundary layers' thickness is proportional to the laminar(turbulent) flow diffusion coefficient size.When the P_r≈Pr_t,Sc≈Sc_t,Le≈Le_t,the turbulent jet velocity,temperature and concentration boundary layers' thickness is proportional to the laminar flow diffusion coefficient.The simulation results and theoretical analysis have the same conclusions.By changing the quantity of pollutants,we have simulated a wide range of formaldehyde emission and its jet velocity,concentration and temperature distribution.In our large number of working conditions,we are awared of the value of the outer jet concentration boundary layer increases with the formaldehyde emission when there is one 1m×1m×1.3m,two 1m×2m×1m,four 1m×2m×1m sources. We definitioned the health of the ventilation control domain is the region which meets the healthy and comfort requirement in the work section on breathing areas.The health of the ventilation control domain was gradually increasing with the decreased velocity.The health of the ventilation control domain can't be simply choosed through the concentration and velocity boundary layer.We need to combine the jet velocity and concentration boundary layer,velocity and formaldehyde concentration to determine the domain.