Design And Test Of Seed Separating Mechanism Of Air-assisted Centralised Seed-metering Lotus Leaf Vein Type For Wheat And Rapeseed

Wheat and rape are both winter grain and oil crops in Anhui province,and their mechanized planting agronomy and sowing time are close to each other and their processes are similar,but they lack excellent dual-use precision seeding technology and supporting devices.In order to solve the problem of poor consistency of discharge of different lines caused by random retention of seeds in the working process of wheat oil and gas conveying type seed sorting device,based on the principle of mechanical and pneumatic combination seed sorting,a kind of collecting and exhaust conveying type seed sorting device with vein structure was designed based on the copying structure.Using dynamic theory,discrete element numerical simulation,DEM-CFD solid-gas coupling simulation and performance test,the simulation parameters of seed particles were calibrated,the key structural parameters of the seed separation device were determined,the coupling model of seed gas interaction was established,the causes of seed retention in the seed separation device were studied,and the key structural parameters were optimized and verified.Its main research work and conclusions are as follows:(1)Carried out parameter calibration of the seed simulation model.The wheat and rape varieties commonly used in the Jianghuai area were selected,and the basic physical parameters of seeds were determined.The simulation and calibration of seeds and materials and interspecific contact parameters were carried out using EDEM software,which provided the basic parameters for the design of key components of a seed separation device and the simulation of solid-gas coupling.(2)The structure design of the sub-device is carried out.Based on the physical parameters and suspension velocity of seeds and the Bernoulli principle,the relevant parameters of key components were defined,and four structural types of straight tube,bellows,alternating wave tube,and sawtooth tube were designed.At the same time,taking the lotus vein curve as the imitation prototype,the curve equation of the lotus vein curve was fitted,a kind of component with the lotus vein type channel was proposed,and the key factors affecting the uniformity of the seed arrangement of the lotus vein device were clarified.(3)The motion characteristics and distribution process of seeds in the seed sorting device were studied.The effect of bending pipe on the motion characteristics of seeds and the flow field distribution was studied using the DEM-CFD gas-solid coupling method,and the length of the fold in the supercharging pipe was determined.The structure of supercharging pipe and the parameters of the inlet diameter were determined by the all-factor test design,and the seed movement retention of supercharging pipe was analyzed,the cause of which was related to the non-uniform turbulence generated by the structure.Through simulation,the population movement of different busbar radiuses and end cover cone angles of different kinds of channels was compared,and the influence of busbar migration and end cover conical busbar on seed row was analyzed.The seed row uniformity was better when both the end cover conical busbar and the end cover conical busbar were streamlined.With the increase of air velocity,the variation coefficient of discharge consistency of each line decreases and tends to be stable.When the supply rate is higher and the retention rate is smaller,the discharge consistency of each line is better.(4)The performance test of the device was carried out.The bench results show that the consistency coefficient of variation of each row of displacement of wheat at 40 ～ 100 r/min and air flow at 18 ～ 26 m/s is not greater than 3.3%,Rape at a rotational speed of 20 to 50r/min,The variation coefficient of displacement at 16 ～ 24 m/s is not greater than 4.4%,The seed quantity increases with the seed speed,The airflow has less influence on it;Field experiments showed that when the airflow velocity of wheat and rape was 22 m/s and 20m/s,respectively,The mean wheat sowing rate was in the range of 700 to 1400 g / min,The coefficient of variation of displacement is not greater than 3.3%,The mean seeding rate of rapeseed was in the range of 60 to 100 g / min,The consistency coefficient of variation of each row is not greater than 4.0%,Meet the agronomic sowing requirements.