亚洲一区欧美在线,日韩欧美视频免费观看,色戒的三场床戏分别是在几段,欧美日韩国产在线人成

Aiming at the problems of high pulsation and poor uniformity for the wheat seeding method with disorderly seed flow and variable discharge, a pneumatic centrifugal combined precision seed metering device for wheat was designed. The pneumatic seed filling and centrifugal seed cleaning method were used in the seeder to make seeds in an orderly and uniformly flow. The key parameters were designed firstly. Then, the kinematics of the seed filling and seed dropping processes were modeled and the initial range of filling and dropping angles were determined. Finally, the orthogonal rotational combination test was conducted by using the gas-solid coupled simulation method DEM-CFD. The results showed that when the seed filling angle range was further reduced to 36°～56°, the seeder had better seed carrying performance. Meanwhile, when the seed dropping angle range was further reduced to 43°～63°, the seeder had better discharge performance. On the basis of that, a laboratory test was carried out. The seed filling angle, seed dropping angle and seed disc speed were taken as the test factors and the missed seeding rate, replay rate and straight line seed drop rate were taken as the indexes. The results showed that the seeder had a good performance when the seed filling angle was 47.75°, the seed dropping angle was 52.48°, and the rotational speed was 635.5r/min. At this time, the rate of missed seeding rate was 2.78%, the replay rate was 3.73% and the straight line seed drop rate was 93.46%. The results of the validation tests were in general agreement with the optimization results. The field test results showed that when the seed filling angle of the inner side of the seed tray was 47.8° and the seed drop angle of the lower side was 52.5°, and the speed of the seed tray was in the range of 552～800r/min, the sowing leakage rate was lower than 8.9%, the reseeding rate was lower than 4.3%, and the seeding pass rate was higher than 88.6%, which met the requirements of precision sowing of wheat. 