Simulation Analysis And Experimental Study On Positive And Negative Pressure Precision Metering Device For Rapeseed

Rape is the second largest oil crops in the world, its planting area is over 7.33 million hm~2 in China, almost accounting for 1/3 of the cultivated area in the world. But the mechanization level of planting rape is not high. Mechanization seeding is the most difficult technological problem for rape planting. So, it is a very urgent need of practice to research and develop a metering device of high-performance for rapeseed.Based on the structure and metering performance of the positive and negative pressure precision metering device, structural optimization and experimental study were carried out in this paper. All the study, it is hoped to optimizing the structure of the metering device, defining operation parameters, improving the performance indices, including improving eligible index, reducing multiple index and miss index, stabilizing the quality of metering, to afford theoretical foundation for the optimization design of the pneumatic precision rapeseed metering device and the seeding technology for other small grains. The research results included:1) Analysed the operation principle of the positive and negative pressure precision metering device for rapeseed and the aerodynamics of air current field, defined theoretical foundation of solving air current field of the metering device. Also anlysed the forces of rapeseed in seed-sucking area and seed-blowing area, defined the strength model of rapeseed in the metering device.2) Carried out simulation analyses of the air current field in pressing and negative pressing area by ANSYS/CFX software, also analysed the position of blowhole in negative pressing area and the types of hole in the disc, defined influence on the metering device by the above factors. Simulation analysis for coupling of air and rapeseed was also carried out.3) Carried out experimental study on the metering device before optimizing, defined its performance indexes.4) Carried out optimization design and experimental study on the structure parameters according to its working course, got the optimal parameters of the seed case, postion of blowhole, type hole and seeding mouth.5) Finished structure optimization of the metering device, and carried out orthogonal experiment, got the mathematics model about the variation of eligible index, multiple index and miss index along with the influencing factors. Analysed mathematics model using MATLAB, and got the best operation parameters and the best theory indexes of the metering device.