Design and Experiment of Combined Cavity-Type Precision Hole-Drop Seed-Metering Device for Rice

To improve the quality of air suction jujube picker, the CFD-DEM coupled method is used to numerically simulate the conveying process of jujube particles and explore the motion state, particle collision and energy loss of jujube particles in the pipeline. The erosion rate is selected as an evaluation index to discuss the influence of wind velocity, bending angle and diameter on the conveying process. The simulation results show that the collisions between jujubes, as well as the collisions between jujubes and pipe wall have an impact on the conveying performance, and the latter is more significant. The erosion rate is positively correlated with the wind velocity, negatively correlated with the pipe diameter, and the bending angle first decreases and then increases. The influence degree of factors on the erosion rate is: wind velocity > bending angle > pipeline diameter. The optimal parameter combination is a wind velocity of 28 m•s-1, a bending angle of 105 °, and a pipe diameter of 130 mm. At this time, the value of erosion rate is the lowest and the number of collisions and energy loss between jujube particles are reduced by 37.3 % and 13.87 % year-on-year, and those between jujube particles and pipe wall are reduced by 17.45 % and 17.61 % year-on-year, respectively. The test results show that the conveying pipe with optimized structural parameters can reduce the jujube skin damage rate by 2.06 %. The results of this study can provide a reference for the design and optimization of the air suction jujube picker.

Simulation Test and Verification of Material Conveying for Small and Medium-Sized Air Suction Jujube Picking Machine Based on CFD-Dem Coupling

ZHANG,

SHAO,

ZHAO

et al. 2023

Design and Mechanism Study of Seed Filling Room With Staggered Oriented Plates and Vibration

MO,

LU,

ZHANG

et al. 2024

Aiming at the existing rice mechanized seeding technology it is difficult to meet the hybrid rice low seeding volume precision seeding requirements. In this paper, based on the friction characteristics of rice seed and the theory of silo arching, the structure and parameters of seed filling room with staggered oriented plates and vibration in the quantitative seed supply device were designed. EDEM software was used to simulate the working process of the quantitative seed supply device, and it was determined that staggered oriented plates structure in the seed filling room combined with vibration could effectively prevent seed arching, thus improving the uniformity of seed supply. Finally, the results of the simulation analysis were verified by rice quantitative seed supply test. The results showed that the vibration could increase the seed supply frequency by 3.64% for large sowing weight of conventional rice and 5.52% for small sowing weight of hybrid rice. In addition, the analysis of the coefficient of variation of the seed supply frequency by quantitative seed supply devices showed that the vibration effect could increase the stability of seed supply device by 2.47 % for the conventional rice seed and 1.33 % for the hybrid rice seed, which increased the seed supply stability.

Simulation Parameter Calibration and Test of Pak Choi Seeds Based on Discrete Element Method

DUN,

ZHANG,

et al. 2024

Physical property parameter measurements and simulation model parameter calibrations of Pak Choi seeds were conducted to address the lack of accurate parameters for discrete elemental seed discharging simulation tests in the seed-metering device. Firstly, physical tests were utilized to determine the basic physical parameters and contact parameters of Pak Choi seeds. The results of these physical tests served as the basis for determining the range of simulation parameters. The Plackett-Burman test was employed to screen out factors that significantly affected the simulated angle of repose from the test parameters, including static friction coefficient between Pak Choi seeds-Pak Choi seeds and rolling friction coefficient between Pak Choi seeds-Pak Choi seeds. The optimal interval of these two factors was determined using the Steepest Climb Test. Subsequently, the regression equation between the significance parameters and the angle of repose was obtained through the Central Composite Designs test, and the best parameter combinations were obtained with the measured stacking angle of 24.3° as the optimisation target value: Pak Choi seeds-Pak Choi seeds static friction coefficient of 0.486, Pak Choi seeds-Pak Choi seeds rolling friction coefficient of 0.104. Finally, simulation and bench comparison tests were carried out for stacking angle and Pak Choi seed discharger performance evaluation. The relative error of the angle of repose was found to be 0.288%, while average relative errors for qualified sowing rate, replanting rate, and missed sowing rate were all less than 5%. These results demonstrate that calibrated Pak Choi seed simulation parameters are reliable and can serve as a reference for design optimization of Pak Choi seed dischargers in academic research writing standards.