The potato-soil separation device comprising five function areas (i.e., shearing, bending, throwing, cleaning, and conveying) was developed to address the mentioned problems (e.g., soil with high moisture content, large viscosity, and poor separation efficacy) in the harvesting process for winter idle paddy fields of Southern China. Given the kinetic analyses for the potato-soil mixture of five function areas, the crucial factors of the effect of potato-soil separation were determined. Subsequently, the orthogonal test of 4 factors and 3 levels was performed, and the percentage of small soil λ, the percentage of soil adhering to potato tuber γ, and damage rate of potato tuber K were adopted as assessment indexes. Regression analyses and programming for the orthogonal test result were conducted to optimize the device run parameters, and the optimal run parameters included the rotational speed of the soil-crushing mechanism of 84.18 r/min, linear velocity of second-stage lifting chain of 0.75 m/s, and inclination angle of lifting chain of 15.87°. The field experiments were performed with the modified potato harvester. As indicated from the result, the visible potato rate was 94.31% and damage rate of potato was 0.89%, and the requirement of the national standard was satisfied. This study presented technical feasibility data and equipment for potato-soil separation under sticky soils condition.

Reducing potato tuber injury rate is responsible for the optimal design of potato harvester, one of the most important goals. To assess the influence of various factors on potato tubers' impact damage, the impact mechanics model of potato tuber was constructed in terms of the deformation and deformation energy analysis during the collision. Secondly, the orthogonal test was conducted. The impact material, potato varieties, potential energy, impact angle were selected as factors. The comprehensive damage index (DI) was taken as the evaluation index. The results showed that the damage degree of potato tuber was decreased with the increasing of coefficient of restitution of impact material, potato yield strength and collision angle, but increased with increasing potato potential energy. When the impact material is a plank, the potential energy is 1.2 J, the type of potato is Lishu No.6, and the collision angle is 15°, the comprehensive damage index is the lowest, 0.0055. According to the result of the orthogonal test, the mathematical regression model was obtained. At the same time, the verification tests were performed. The verification tests showed that the average error between the predicted data of the comprehensive damage index calculated by the mathematical regression model and the experimental data was 5.22%.

The active agitator is preferred because it enhances the screw feeder's particle flow characteristics more effectively. Utilizing the discrete element method, a discrete element model of pellet feed was constructed to investigate the impact of the agitator on the discharge performance of the screw feeder. As the focus of the investigation, the screw feeder (consisting of a wedgeshaped hopper and a screw conveyor) was studied. By designing a pair of symmetrical agitators in the wedge-shaped hopper, the effects of different directions (forward slewing, reverse slewing, and isotropic slewing) and different speeds of the agitator on the discharge rate, flow pattern, particle velocity, particle trajectory, and particle interaction force of the screw feeder were studied. Findings indicated that the agitator caused a transition from a funnel flow to a mass flow in the hopper, resulting in more particle movement. The increase in the interaction force between particles in the area above the screw conveyor forced more particles to be squeezed into the screw conveyor. The maximum average discharge rate of 27.89 g/s was achieved when the direction of the agitator was FS, which was 10.38% higher than that without the agitator. There was little to no difference in the discharge rate regardless of the agitator's direction and speed. In addition, as the discharge progressed, the particle bed height in the hopper decreased, and the promoting effect of the agitator progressively weakened. The discharge rate of the screw feeder showed a trend of first stabilizing and then decreasing, and the interaction force between particles also showed the same trend of change. As shown from the aforementioned studies, the discharge performance of the feeder can be greatly enhanced by installing an agitator. The research findings shed light on how the screw feeder's agitator works to boost its discharge performance, laying the groundwork for additional improvements to its design.

The repeated cutting of forage can cause grass breakage and affect the performance of the forage drum mower in harvesting forage. Also, it is worth paying attention to the effect of airflow around the cutter on the cutting and feeding processes. To explore the characteristics of the airflow field around the cutter and optimize the key parameters of the airflow, an analysis of the airflow field of the forage drum mower equipped with twisted blades, tilting discs, and guide plates was conducted through numerical simulation. Furthermore, an orthogonal experiment was carried out by using the numerical simulation model. According to the experimental results, the optimal velocity of the airflow for gathering, lifting, and feeding was reached when the disc speed was 2000 r/min, the blade twist angle was 8°, the disc tilt angle was 4°, and the number of guide plates was 2. On this basis, a prediction model of airflow parameters was constructed, and the parameters of airflow around the cutter were measured on a test bench. According to the measurement results, the results of prediction by the model were consistent with the simulation results. Also, compared with the data of airflow measurement, the average error of the model prediction value was −5.83% for the velocity of the gathering airflow, 2.37% for the velocity of the lifting airflow, and 4.20% for the velocity of the feeding airflow, which demonstrates the reliability of the simulation results and prediction model. The results of this research provide a practical reference for the optimal design of the forage drum mower.