Performance Analysis And Optimization Design Of New Type Inertial Impactor

With the continuous advancement of the world’s industrialization process,the frequency of smog around the world is increasing,and the degree is getting worse.Environmental pollution,especially atmospheric particulate pollution,has become a major challenge for contemporary society.Atmospheric particulate matter is not only a product of reduced atmospheric visibility and photochemical pollution,but also increases the morbidity and mortality of respiratory and cardiovascular diseases.As aerosol particles with a smaller aerodynamic diameter,particles with an aerodynamic diameter of less than 0.5μm(PM_0.5)are more healthful to humans than atmospheric sol particles due to their low quality,ultra-high reactivity,and high specific surface area.Cause more serious adverse consequences.The research on PM_0.5 pollution has become more and more urgent,and the research on the inertial impact collector is the basis for this work.The impact collector based on the principle of inertia is an inertial impactor,which is a particle size separation device that can effectively separate submicron aerosol particles according to their aerodynamic particle size.The cutting diameter of the traditional inertial impactor is less than 0.5μm,and the wall loss is generally larger.There is no good solution to the problems of aerosol particles bounce and overload on the impact plate.Therefore,it is of great significance to design a new type of inertial impactor that collects PM_0.5 in the atmosphere.This paper takes the new inertial impactor as the research object,carries out the design of the key structural parameters of the inner flow channel,the analysis of the flow field characteristics,the influence of different factors on its separation characteristics and the dynamic optimization design.The main research work of this paper is as follows:（1）The collection principle of the traditional inertial impactor is introduced,and then the basic working principle of the secondary inertial impact sampler is discussed;in the case of determining the sampling flow and cutting diameter,the analytical formula for the size of the acceleration nozzle of the secondary inertial impactor is derived;based on inertia Classical impactor design theory,design a new type of inertial impactor for detecting PM_0.5 in the air;（2）Based on the theory of computational fluid dynamics,establish a numerical model of the flow channel in the new inertial impactor,and obtain the key performance parameters of the new inertial impactor such as separation efficiency,wall loss and cutting diameter through numerical simulation calculations.（3）The working environment of the new inertial impactor and the influence of machining errors on its separation performance are studied;on the basis of the computational fluid dynamics model of the flow channel in the new inertial impactor,the different sampling flow rates and different ellipses of the inertial impactor are studied.Numerical simulations are carried out under the conditions of the ratio of the long and short semi-axes of the groove impact plate,the distance between the first and second stages of different acceleration nozzles and the impact plate,which reveals the influence of different factors on the separation characteristics of the new inertial impactor.（4）Taking the highest separation efficiency of the new inertial impactor and the least wall loss as the optimization goals,taking each sampling flow rate and different design parameters as design variables,using the central composite design method to design tests,and combining computational fluid dynamics theory to establish a new type of inertial impact The response surface optimization model of the blaster is dynamically optimized,and the optimized new inertial impactor is modeled and numerically simulated.