Study On The Flow State Of Cigarette Smoke In Filter Based On CFD

With the in-depth study of smoking and health,smokers pay more and more attention to the health problems of smoking and demand on the quality and taste of cigarettes.In order to reduce the tar and harmful components,it is very important to study the physical structure of cigarette filter.Therefore,this paper used ICEM CFD 15.0 software and Fluent software 15.0 to establish mathematical model of cigarette filter and simulate the flow of smoke in the filter.It revealed the flow characteristics of smoke in filter through the research of physical and chemical data and provided technical support for further research of cigarette filter.The main research contents are as follows:(1)The porosity of three kinds of filter was measured which were 0.66~0.81;Based on self-developed cigarette smoke experiment machine,the pressure at the suction end,the velocity at the suction end and the velocity near the tobacco end of the filter were measured.The linear fitting between the velocity and the pressure at the suction end was carried out to find that accorded with Darcy’s law,which provided the boundary conditions and model validation for the mathematical model of filter.(2)The main components and their mass fractions in cigarette smoke were obtained which collected by Cambridge filter.Through the collection of particles in cigarette smoke by Cambridge filter,the filtration efficiency of three different structure filters for particle in cigarette smoke was calculated.The filtration efficiency of three kinds of filters with different structures for particle through experiments were: unitary filter 40.13%,binary filter 39.83% and groove filter 43.90%.It provided ideas for the subsequent verification about mathematical model of the filter.(3)The transient numerical simulation of 3D cigarette smoke flow in filter was conducted by using the filter as a uniform porous medium and using UDF with mass,momentum and component transport equation.The changes of smoke flow field in the three kinds of filter,the smoke velocity,pressure and mass fraction distribution of particle were investigated in the filter during cigarette smoking process.The following conclusions are drawn: The smoke velocity is small at the beginning of the suction.With the suction proceeding,the smoke velocity increases continuously,and then decreases near the ending of the suction.In unitary and binary filter,the velocity of smoke in the central part of the filter was obviously higher than that in the peripheral part at each time of smoking,but the velocity of smoke in the groove part was obviously higher than core part of the filter;From near tobacco end to suction end,the pressure presented a gradual decreasing trend;The filtration efficiency of particle was groove filter > unitary filter > binary filter,and the filtration efficiency of carbon monoxide was also groove filter > unitary filter > binary filter.(4)It was valid to realize the transient simulation of smoke flow in cigarette filter by using mass conservation,momentum conservation,component transport equation,combined with UDF which validated by filter efficiency and Darcy’s law.