Research Of The Flow Field In The Respiratory Cavity Of The Powered Air Supply Respiratory Protection Device

Since the outbreak of COVID-19,the virus is spreading all over the world,which has a huge impact on people’s production and life,draws attention to respiratory protection.according to relevant research,the viruses that cause respiratory infections enter the body mainly through the eyes and nose and mouth,to reduce the risk of infection,safe and comfortable respiratory protection is particularly important.With this background,this paper investigates the flow field in the respiratory cavity of the powered air supply respiratory protection device,by combining numerical simulation with experiment,to analyze the influence of mask structure and air supply angle on the pressure,CO₂concentration,airflow velocity and temperature in the respiratory cavity,on this basis to research the brightness retention and stability of the face shield.First,the composition and working principle of the powered air supply respiratory protection device are described,to investigate the characteristics and flow state of the fluid in the respiratory cavity,establish the model of gas jet and leakage in the breathing cavity,and the human respiratory model under moderate labor intensity.It lays a theoretical foundation for the subsequent numerical simulation analysis.Secondly,simplifying human facial features,the simplified model of the fluid domain in the respiratory cavity with different mask structures is established,and in both cases with and without respiratory disturbance,the effects of mask structures on the flow field in respiratory cavity was analyzed by Fluent software,to obtain the optimum mask structure,and change the air supply angle based on this basis,to analyze the relationship between facial gas flow rate and CO₂ concentration in the nose and mouth of human body,find out the reasonable range of supply air angle.Based on the above analysis,a concrete model of fluid domain with facial features is constructed and numerically simulated,comparing the simulation results with the simplified model,analyze the rationality of the simplified model and the correctness of the related conclusions.Then,within a reasonable range of air supply angles,numerical simulation and analysis of the temperature field in the respiratory cavity,combined with the temperature distribution and thermal convection in the respiratory cavity,to explore the effect of air supply angle on the brightness of the face shield.Thus further optimizing the air supply angle,and at the optimum air supply angle,the pressure load of the fluid domain in the respiratory cavity is applied to the face shield for fluid-structure coupling calculation,observe the relationship between the thickness of the face shield and the deformation.analyze the influence of the thickness of the face screen on its stability,determine the optimal thickness of the face screen.Finally,build the experimental platform of data acquisition,carrying out experiments on human wearing,to detect pressure and CO₂concentration in respiratory cavity,verify the correctness of the numerical simulation,to provides reference for the optimization of the following respiratory protective devices.