Simulation Analysis Of Working Process Of Air Blown Corn Precision Seed-metering Device Based On DEM-CFD Coupling Method

In this paper, air blown precision seed-metering device and corn is considered as the research object. By making research on gas-solid coupling and DEM, the feasibility of analyzing air blown precision seed-metering device with the method of DEM-CFD(Computational Fluid Dynamics,CFD)was identified. Then availability is verified that using DEM-CFD coupling method and the software introduced in this paper to study air blown precision corn seed-metering device through making research on computer simulation and bench test results. Finally, software LSY excogitated by project team is utilized to optimize the configuration of corn seed-metering device, in order to reflect its value in practice that the new method applied in agricultural machinery.The main innovation of this article is engendering a new kind of digital design method based on DEM-CFD coupling technique for air blown precision seed-metering device. It can simulate details of the working process of air blown precision seed-metering device accurately. We can also change the CAD model of precision seed-metering device of (CAD drawing Figure) to analyze performance of precision seed-metering device of different structure and size, such as single seed rate, cavity ratio and double seed rate. Thus we achieve the goal of optimizing structure parameters and size of air blown precision seed-metering device. It provides a new way for research and design of other agricultural machinery.The main work and conclusions are as follows.(1) The drag coefficient is studied in this part about physical and mechanical property of the seed. Method of calculating drag coefficient of different sphericity is discussed for different areas in the laminar flow zone, turbulent flow zone and transition zone. Sphericity of three kind of corn used by the research group is calculated. That provides a theoretical basis and reasonable data for setting parameters of two-dimensional simulations of air blown seed-metering device.(2) The bench test is implemented about the air blown seed-metering device, includes to design a kind of air blown seed-metering device and its fixture, to conduct performance tests on the PSJ test bench of seed-metering, to measure the gas pressure and velocity fields, to record the working process by high-speed camera, to record the results, such as single seed rate, cavity ratio and double seed rate. Seed throwing angle, seed throwing trajectory, velocity is analyzed through BLASER'S MAS.Then we get the conclusion the bench test results are credible and provide reliable test data for further analysis of comparison to simulation.(3) Working process of air blown corn precision seed-metering device is simulated by Discrete Element Method software developed by project team independently. This part records simulation results of seeding performance, seed throwing angle, seed throwing trajectory, velocity of air blown precision corn seed seed-metering device under two conditions aerated and without blowing. Then disposal and analyze the results. The simulation results and the bench test results are compared and analyzed. Then we get the conclusions that two-dimensional LSY software is available and scientific developed by project team independently, which prepares the basic facts for the use of LSY software to optimize structure of air blown seed-metering device. Finally, some simulation parameters are to be tested exploringly, which makes the simulation results more scientific through the specification analysis of the parameter settings.(4) This part simulates different values of structure of air blown corn precision seed-metering device by use of discrete element method software, then find the optimal parameters. Optimum design of air blown corn precision seed-metering device primarily depends on changing several factors which may affect the performance of the seed-metering device and which change has a positive impact on performance of the seed-metering device. In order to achieve optimal design of seed-metering device, the structure of the best performance of the seed-metering device is selected. We found performance of seed-metering device has been significantly improved from the working results of the seed-metering device. Finally, we get the conclusion that the goal of optimization design is achieved by using software developed by project team independently.