Study On Active Protection Technology Of Fluid Dynamics In Hospital Specific Space

The outbreak of the new coronavirus pneumonia in 2020 has caused huge losses to the world.Infectious diseases of the respiratory system have long existed in human society.As a special gathering place for people,hospitals are likely to cause cross-infection of respiratory infectious diseases between doctors and patients.This article aims at the specific area where the doctor and the patient are in close contact during the doctor’s consultation,and uses fluid dynamics to explore an active protection method and facility to block the spread of droplets and aerosols.This article first analyzes the propagation mechanism of particles exhaled by the human body in indoor air from the theoretical perspective.A model of the size distribution of particles exhaled by the human body is given.The control equations related to indoor heat transfer and flow and the turbulence model used are given.Based on the particle trajectory model,the force of the particles exhaled by the human body in the indoor air flow field is analyzed.Then combine orthogonal experimental design and numerical simulation to determine the relevant design parameters of the protective equipment.The"heat plume"effect produced by the human body can cause the particles exhaled by the human body to spread to the space where it is located.It is proposed to suppress the thermal plume effect of the human body through top-down ventilation.Place an air distribution device on the upper part of the local space where the doctor is receiving the consultation.Set a return air vent at the bottom of the table.Analyze from the three factors of equipment air distribution area,air distribution wind speed and vertical distance between the air distribution board and the desktop.Select the L₉（3⁴）orthogonal experiment table,and use the average concentration of particles in the center of the breathing center of the doctor and the patient as the experiment index.The orthogonal experiment results are analyzed by the range analysis method,and the optimal level combination of various factors of the protective equipment in the test range and the influence of each factor on the protective effect of the equipment are determined.Combining energy consumption analysis and the effective protection area of doctors,determine the protection principle of minimum wind speed.Further study the protective effect of the equipment through the method of numerical simulation.Based on the relevant parameters of the protective equipment obtained in the orthogonal experimental design,the design model of the protective equipment is given,and the characteristics of the flow field generated by the equipment are analyzed,and then the influence of the human body on the flow field generated by the equipment is analyzed.Then,through numerical simulation,it is obtained that the air distribution speed of 0.2m/s and 0.3m/s,the patient’s different exhalation intensity,the safe distance of the doctor’s breathing area,the air distribution speed increases by0.1m/s,and the protection effect of the equipment is significantly enhanced.Use transient numerical simulation to calculate the air distribution speed required to suppress the biological particles produced by the patient’s cough.Under the air distribution speed of 0.2m/s,compare the protective effect of the equipment when the patient is at different positions and different breathing intensities.Finally,the protective effect of the actual equipment is verified through biological experiments.Determine the feasibility of the tracer bacteria+selective medium selected in this experiment from multiple angles,and introduce the experimental equipment from the simulation system of human exhaled droplets and the sampling system of biological particles.Carried out selective medium efficiency experiment and protective equipment utility biological experiment.Finally,statistics and analysis of plaque collected and cultured through experiments are conducted to clarify the protective effect of the actual equipment.