Research And Numerical Simulation Of Gas-Solid Two Phase Flow In Raw Grain Air Classifier

In recent years,the total output of grain crops in our country is increasing,the mechanization level of harvesting grains improved year by year,the raw grains contain more and more impurities.With the sustained and rapid development of food processing industry,grains’ cleaning has become the bottleneck to restrict its development.At present,the effect of the equipment,used for grains’ cleaning,is not good,and the efficiency of it is low.In the practical application background above,study on air separation equipment,used for grains’ cleaning,is very important.In this thesis,the computational fluid dynamics software FLUENT has been used to simulate the mainstream raw grain air classifier on the market.The main contents include:First,a simulation of internal flow was made in the raw grain air classifier.Gas flow field simulation is the base of the next step about two-phase flow simulation.We has made an analysis of the distribution of internal gas velocity,distribution of pressure and turbulence structure,include turbulence intensity,turbulence kinetic energy,turbulence kinetic energy dissipation rate.Next,using the single factor method to analyze the impact of different structural parameters,wind direction,air inlet shape,air outlet position,to the gas flow field.On that basis,we made a structural optimization to the raw grain air classifier.And then re-simulated,it was compared with the previous.The simulation results show that the improved air classifier,its distribution of internal gas velocity,distribution of pressure and turbulence structure is more reasonable than the previous.Finally,internal gas-solid flow was simulated in the raw grain air classifier.DPM model was used in the simulation of the solid particles.Through the analysis,we obtained the particle trajectories in the air classifier.Thus it can be seen,by numerical simulation the flow orderliness in the raw grain air classifier has been studied.The results,with engineering and practical significance,have reference value to the design and structure optimization of air classifier.