Study On The Model Of Corn Grain Traversing The Holes Of The Screen In Airand-screen Cleaning Device

With the constant increase of the corn planting area, corn has become the first major food crops in China. And the national corn area harvested by mechanization from 10.67 million hectares in 2010, to21.33 million hectares in 2014.The level of corn harvested by mechanization has been higher than 56%.However, compare to western countries that have basically achieved all mechanical work, our country has a big gap. The application of corn combine harvester is the important guarantee to realize mechanization of corn harvest. But compared with western developed countries, the work quality of corn combine harvester is not high in China, It’s easy to see low cleaning rate and high impurity rate.Domestic scholars have made more research on the corn combine harvester header and less study on cleaning device.In this article, the process of corn grain traversing the holes of the whole screen was deeply studied. And the probability model of single spherical grain traversing the holes of the whole screen in the air-and-screen cleaning mechanism was established; The multi and single factor simulations on probability and efficiency of corn grain traversing the holes of screen were simulated based on CFDDEM coupled method. The main work are as follows(1)The process of materials traversing the screening is an important work of corn combine harvester cleaning device. On the basis of summarizing some researcher’s work experiences, this paper analyzes the mechanism of material traversing the screen.And based on the basic theory of mathematical statistics. The model of a single spherical materials on the length of the entire screen surface traversing sieve probability formula was established.(2)In this paper, Transmitting mechanism of grain on the screen was analyzed deeply. And in order to obtain the outstanding performance of the air-and-screen cleaning mechanism, the probability equation of single spherical grain traversing the holes of the whole screen was established based on the theory of probability.(3)Spherical corn grain cleaned by air-and-screen was simulated based on CFD-DEM coupled method. Inlet’s average gas velocity and outlet’s pressure values was measured based on the testplatform. And this work lay the foundation for the simulation. By using the high speed camera. The corn grain distribution was measured. Corn grain focus on the middle and end of the screen and little appear on the head.(4)Single precision solver, pressure-based solver, standard ? ?? model were chosen in Fluent. In order to simulate the movement of the screen, the layering mesh model was setting and UDF was defined. Velocity-inlet and pressure-outlet was set as the boundary condition, and outlet pressure was defined by UDF. Soft-sphere contact model was chosen and parameters of material, geometry,movement was setting in EDEM.(5)Inlet air velocity of cleaning device, screen angle, the vibration frequency of screen surface were chosen as factors of testing, and the average probability and average efficiency of corn grain traversing the holes were test index, single factor levels an Quadratic rotational regression design of experiments was simulated. And the experiment results were: the average probability of particle traversing the holes decreased with increasing of angle of screen fixed and the air velocities, the average probability of particle traversing the holes decreased then increased with increasing of frequency of screen vibrating; The average efficiency of particle traversing the holes increased with increasing of the air velocities, the average efficiency of particle traversing the holes increased then decreased with increasing of frequency of screen vibrating, The average efficiency of particle traversing the holes decreased with increasing of angle of screen fixed. By multiple factors quadratic orthogonal rotating combination design of experiment, The response surface figure and regression mathematical model was obtained between the average probability and efficiency of the corn grain traversing the holes and screen vibrating, the air velocities, frequency of screen vibrating.