Research and Experiments of Hazelnut Harvesting Machine Based on CFD-DEM Analysis

Abstract

To solve the problem of difficult hazelnut harvesting in mountainous areas of Liaoning, China, a small pneumatic hazelnut harvesting machine was designed, which can realize negative pressure when picking up hazelnut mixtures and positive pressure when cleaning impurities. The key structure and parameters of the harvesting machine were determined by constructing a mechanical model of the whole machine and combining theoretical analysis and operational requirements. To explore the harvesting machine scavenging performance, Liaoning hazelnut No. 3 with a moisture content of 7.47% was used as the experimental object. Firstly, the terminal velocity of hazelnuts and fallen leaves was measured using a material suspension velocity test bench. Secondly, the gas–solid two-phase flow theory was applied comprehensively, and the motion state, particle distribution, and air flow field distribution of hazelnuts from the inlet to the outlet of the pneumatic conveying device were simulated and analyzed using the coupling of computational flow fluid dynamics method (CFD) and discrete element method (DEM) to evaluate the cleaning performance from the perspective of the net fruit rate of hazelnuts in the cleaning box. Finally, a Box–Behnken design experiment was conducted with the sieve plate angle, the distance of the sieve plate, and the air flow velocity as factors and the net fruit rate of hazelnuts as indicators to explore the influence of the three factors on the net fruit rate of hazelnuts. The parameter optimization module of Design-Expert software was used to obtain the optimal combination of parameters for the factors. The experimental results show that the test factors affecting the test index are the following: the air flow rate, the angle of the screen plate, and the distance of the screen plate. The best combination of parameters was an air flow velocity of 14.1 m∙s−1, a sieve plate angle of 55.7°, and a distance of the sieve plate of 33.2 mm. The net fruit rate of hazelnuts was 95.12%. The clearing performance was stable and can guarantee the requirements of hazelnut harvester operation, which provides a certain theoretical basis for the design of a nut harvester.

Simulation and Optimization Experiment: Working Process of a Cleaning Device for Flax Combine Harvester

“…After analyzing the impact of various operating parameters on the cleaning device's performance, we identified optimal working parameters for use during its operation. We then confirmed the simulation results' validity using actual field tests [10]. The established CFD-DEM coupling simulation model presented in this paper can predict the functioning of the flax cleaning device's operating process.…”

“…The Design Expert software's optimization solver was employed to optimize and solve regression equation models ( 9) and (10) those under the object (11). The significance of the kernel impurity content (++++) and the cleaning loss rate (+++++) were considered.…”

Numerical Simulation of an Online Cotton Lint Sampling Device Using Coupled CFD–DEM Analysis

“…The primary emphasis in the numerical simulation of the gas-solid two-phase flow of agricultural materials is on near-spherical particles, including wheat, soybeans, corn, and similar materials. The materials are typically transformed into spherical particles through the utilization of equivalent diameter, material characteristic parameters, contact parameters, and other relevant factors [14][15][16][17][18][19]. Subsequently, numerical simulations of gassolid two-phase flow are conducted using computational fluid dynamics (CFD) software and the discrete element method.…”

Numerical Analysis of Friction-Filling Performance of Friction-Type Vertical Disc Precision Seed-Metering Device Based on EDEM

“…Gao et al studied a quantitative feeding device with a staggered symmetrical groove wheel by using the DEM [19]. Ren et al coupled computational fluid dynamics (CFD) and the discrete element method (DEM) to simulate and analyze the hazelnut motion state, particle distribution and air flow field distribution of a pneumatic conveying device from inlet to outlet, and evaluate the cleaning performance from the perspective of the net fruit rate of hazelnuts inside the cleaning box [20]. Xiao et al used DEM-CFD to analyze the effects of three types of seed guide tubes on the movement characteristics of seed particles in an oilseed seed drill [21].…”