Design And Test Of Metering System Of Pneumatic Distribution Rice Direct Seeder

Rice is one of the main food crops in China,and plays an important role in ensuring food security.With the deepening contradiction between supply and demand caused by the lack of rural labor force,rice direct seeding technology has attracted more and more attention due to its cost-saving and efficiency-enhancing effect.As the key technology of rice direct seeding technology,seed metering system plays an important role in the quality of seeding.Based on the existing rice direct seeder in Shanghai farm,a new rice direct seeding system has been developed in order to improve the operation quality and efficiency.The system can be adapted to live seeding of small grain size,such as rice and wheat.The number of rows of seeding is 16.The tractor matched with the system is John Deere 6B-1354.On the premise of systematically analyzing the research status of pneumatic distribution seeding technology at home and abroad,aiming at the problems of low efficiency and high injury rate in high-speed operation of the existing rice direct seeder,the design of the whole pneumatic distribution seeding system was completed according to the design concept of "one device and multiple lines",and the key technical problems in the system were studied.The whole system consists of seed quantifier,feeder,distributor and transportation pipeline.EDEM-Fluent coupling software is used to simulate the main working process and optimize the parameter design according to the simulation results.On this basis,the key components were processed by 3D printing technology and tested on the seeding performance test bench.The main conclusions of this paper are as follows:(1)Using the Nanjing 9108 seed model as the particle model,under the condition of 180.054 g/s seed mass flow rate(corresponding to 10.8 kg/mu and 10 km/h operation speed),the orthogonal simulation experiments were carried out on the main factors affecting the particle dispersion effect of bellows.Through the range analysis of simulation results,the main and secondary factors were determined as follows:radius of bellows>length of bellows>length of bellows.The optimum parameters of bellows are determined as follows:the radius of the bellows is R=8mm;the length of bellows is L2=500mm;the distance of bellows is S=40mm;and the length of bellows is L1=16mm.The EDEM-Fluent coupling simulation experiment was carried out with the optimal scheme.The variation coefficient of particle distribution in the plumb pipe was 3.46%.(2)The pneumatic distribution seed metering system designed in this paper was tested in laboratory.The results showed that the bellows length L2[400 mm,500 mm]was the best solution to satisfy the three requirements of seeding quantity at the same time,when the mass flow rate of seeds was 33.507 g/s,67.014 g/s and 100.521 g/s(corresponding operation speed was 10 km/h,sowing quantity per mu was 2 kg,4 kg and 6 kg).When the length of bellows is 500 mm and the mass flow rate of seeds is 33.507 g/s,67.014 g/s and 100.521 g/s,the coefficients of variation of consistency of each row of the system are(3.26±0.46)%,(2.11±0.54)%and(2.37±0.27)%,all of them are within the optimal solution range,which proves that the design method of Bellows Based on EDEM-Fluent coupling is feasible.(3)The output wind speed of the bellows corresponding to the system with length of 300 mm,400 mm,500 mm and 600 mm was taken respectively;under the condition of ensuring the same mass flow rate of the seeds transported,a repetitive test was randomly selected for each bellows length as the sample of the displacement test;the correlation analysis of the two was carried out by SPSS,and the Pearson correlation was found in four groups of experiments with different bellows length.The coefficients are-0.022,-0.323,-0.046,-0.043,respectively.In this seed metering system,the correlation between the air velocity at the nozzle and the seed discharge at the corresponding nozzle is not significant.(4)Under the optimum parameters of pneumatic seed metering system designed in this paper,when the mass flow rate of transported seeds is 33.507g/s,67.014g/s and 100.521 g/s,the coefficient of variation of consistency of each row of the system is(3.26±0.46)%,(2.1 1±0.54)%and(2.37±0.27)%,which conforms to the national standards.