Simulation Analysis Of Working Process Of Air-blowing Seed-metering Device Based On Coupled EDEM-FLUENT

This paper is on the based of domestic and foreign gas-solid coupling theories, a kind ofair-blowing seed-metering device and JiKe Soybean are treated as research objects, the seedparticles are treated as discrete media, through Newton’s law each particle’s motion can besolved, as The Discrete Element Method (DEM); the gas is treated as continuous media,through solving Navier-Stokes equations the gas’ motion can be obtained, as TheComputational Fluid Dynamics (CFD); The two way coupling effect of gas-solid is takeninto consideration finally. On the above foundation, we can simulate and analyze somedifferent parameters of the seed-metering device by EDEM-FLUENT coupling method,looking forward to establish a novel method to improve existing seed-metering device anddesign new types of seed-metering device. The main work and results of the paper are asfollows:(1) The EDEM software and EDEM-FLUENT coupling method have been analyzed.The results of analysis are as follows: The contact and impact is simulate betweenparticles-particles and particles-boundary by Hertz-Mindlin (no slip) and Linear SpringContact Model; The two way coupling effect of gas-solid is treated by Eulerian-Eulerianmethod; The Drag force is solved by Ergun and Wen&Yu (Gidaspow) Model; The impact ofthe Lift force and the Heat Transfer are ignored.(2) The soybean seed has been simplified to two models of spherical particle andcombination sphere particle. In the condition of four rotational velocities (13.99r/min,20.33r/min,26.67r/min,33.01r/min), the working process of the seed-metering device withoutgas (the type hole wheel) by EDEM, and then I have done a comparative analysis betweensimulation and experimental results. The results are as follows:①For the two particle models, the trend of single seed rate and cavity ratio is same asthe test, when the rotational velocity of the wheel increase, the single seed rate decrease, thecavity ratio increased; the double seed rate has no change law. When the rotational velocityis low, the relative error is less than6%; when the rotational velocity reaches33.01r/min,the relative error of combination sphere particle is more than13%.②For the two particle models, the dropping angles of simulation is less than the test, but when the wheel’s velocities change, the trends of simulation and test are the same, andthe relative error of combination sphere particle is less than spherical particle.③For the two particle models, the trajectory of seed which is closed to the wheel bysimulation is different from the test, but the trends of simulation and test are the same, thesimulation trajectory of spherical particle is closer to the test track.④The simulation velocity of spherical particle is more than combination sphereparticle’s, but the results which simulate combination sphere particle is closer to the test inthe seeding performance and the dropping angles.(3) The complete flow model has been built in GAMBIT, then the flow model has beensolved by FLUENT, through Analyst Module the principle of blowing has been verifiedfinally. Specific methods for solving: in moving area, The problems of fluid flow isprocessed by the Sliding Mesh Method; numerical simulation is solved by Pressure-BasedSolver; convective term is dispersed by the Second Order Upwind in precision control; theSpeed-Pressure Coupling is calculated by SIMPLEC.(4) The flow model has been simplified. In the condition of three intake pressure (0.4kPa,1.2kPa,2.0kPa, corresponding to the airflow velocity:6.582m/s,10.327m/s,12.845m/s) and three rotational velocities (20.33r/min,26.67r/min,33.01r/min), throughEDEM-FLUENT Coupling Module, the working process of the air-blowing seed-meteringdevice have been simulated. Coupling results, simulation results without gas by EDEM andtest results have been analyzed. According to both contrastive analysis, the followingconclusions can be drawn.①Either the coupled simulation or test, in certain pressure, when the rotational velocityof the wheel increase, the single seed rate decrease, the cavity ratio increased, the trend ofsingle seed rate and cavity ratio is same as the test, the double seed rate has no change lawand the proportion is less than1%; when the intake pressure is2.0kPa, the relative errorbetween the coupling results and test results is minimized and the proportion is less than5%.②In contrast with the EDEM simulation results, the paper has found that blowingeffect on the seeding performance impact is not obvious at low rotational velocity, but thecoupling results and test results are very close.③Though the trajectory of seed which is closed to the wheel by coupled simulation isdifferent from the test, but the trends of movement in the three pressure is the same, and thesimulation trajectory when the pressure is0.4kPa is closer to the test track than the othertwo pressure. In summary we can see, the analogue simulation is an ideal test, and demands highlythe parameters and model processing. This paper initially proved that usingEDEM-FLUENT coupling method to research the air-blowing seed-metering device isfeasible.