Search Results (22)

As a key device for precise feeding in aquaculture, feeders directly affect feed utilization efficiency and farming profitability; however, pneumatic pond feeders commonly exhibit poor spreading uniformity and low feed utilization. In this study, a dual-sided air intake structure incorporating a triangular flow-splitter plate was added inside the feed chamber, and the spreading process was simulated using a coupled computational fluid dynamics–discrete element method approach to analyze the motion mechanisms of feed pellets within the feeding device. A rotatable orthogonal composite experimental design was employed for the multiparameter collaborative optimization of the feed chamber height ($h$), the triangular flow-splitter plate width ($d$), and its inlet angle ($\alpha$). The results demonstrated that the triangular flow-splitter plate renders the velocity field within the device chamber more uniform and reduces the coefficient of variation ($CV$) of circumferential pellet distribution to 18.27%, a 22.19% decrease relative to the unmodified design. Experimental validation using the optimal parameter combination confirmed a mean $CV$ of 17.02%, representing a 24.45% reduction compared with the original structure. This study provides a theoretical foundation and reliable technical solution for precise feeding equipment in aquaculture. Full article

To address the issue that existing raisin foreign object removal equipment cannot eliminate surface contaminants adhered to raisins through non-washing methods, this paper proposes an adhesive foreign object removal method based on “rapid freezing–rolling extrusion separation-airflow screening”. A raisin adhesive foreign object removal device was designed based on this method. The separation and removal processes of adhesive foreign objects were analyzed and optimized through simulation, followed by device fabrication and performance testing. Starting from the separation process of raisins and adhesive foreign objects, we conducted experimental studies on quick-freezing separation, determined the most suitable separation method based on experimental results, and performed structural design of the equipment accordingly. To conduct simulation analysis and optimization, material parameters were calibrated. The working process of foreign object separation was simulated and optimized using discrete element method (DEM) simulation, verifying the equipment’s separation capability for different adhesive foreign objects while determining the optimal rotational speed of 600 r/min. Through EDEM-Fluent coupled simulation, the working process of foreign object removal was analyzed and optimized, validating the influence of flow field on foreign object removal and determining the optimal air velocity of 11 m/s. The equipment was ultimately fabricated, with further parameter optimization and comprehensive performance testing conducted. The final optimal rotational speed and air velocity were determined as 650 r/min and 11 m/s, respectively. In terms of comprehensive performance, the equipment achieved a separation rate of 93.76%, damage rate of 3.05%, residue rate of 4.28%, removal rate of 94.52%, carry-over ratio of 71:1, and processing capacity of 120 kg/h. Full article

This study investigates the interaction between airflow and low-density bulk particles within vertical screw conveyors and examines its impact on conveying performance. A combined simulation approach integrating the Discrete Element Method and Computational Fluid Dynamics was employed to model both single-phase particle flow and gas–solid two-phase flow. A periodic model was developed based on the structural characteristics of the conveyor. Particle motion dynamics under both single-phase and coupled two-phase conditions were analyzed using EDEM and coupled Fluent-EDEM simulations. The effects of key operational parameters, including screw speed, filling rate, and helix angle, on mass flow rate were systematically evaluated. A comprehensive performance index was established to quantify conveying efficiency, and its validity was confirmed through analysis of variance on the regression model. Finally, the response surface methodology was applied to optimize parameters and determine the optimal combination of screw speed and filling rate to enhance mass flow efficiency. The results indicate that the gas–solid two-phase flow model provides a more accurate representation of real-world conveying dynamics. Future research may extend the model to accommodate more complex material conditions. Full article

Porosity is the key factor affecting a medium’s tortuosity, effective evaporation area coefficient, and ventilation resistance, and further affects the drying efficiency, energy consumption, and drying uniformity in the drying process. To reveal the dynamic variation characteristics of porosity in paddy flow layer, an air convection drying apparatus was established and a mathematical porosity model was established based on response surface methodology. The reliability of the model was verified through EDEM–Fluent coupled digital simulation and experiments. The research results show that under different paddy flow rates v_d (0.01 m/s, 0.03 m/s, 0.05 m/s), different moisture contents M_c (14% w.b., 23% w.b., 32% w.b.), different wind speeds v_w (0.4 m/s, 0.6 m/s, 0.8 m/s), and different layer thicknesses L (100 mm, 150 mm, 200 mm), the porosity values obtained by the porosity measurement device range from 39.562% to 46.006%. The relative errors between the actual values (ε_r), the simulation values (ε_s), and the predicted values (ε_p) are all within ±1%. Moreover, the obtained mathematical porosity model has high reliability (R² = 0.968). The Conclusions provide an analysis method for dynamic change characteristic parameters and basic data for the dynamic change of porosity to reduce drying energy consumption, improve the drying power coefficient, and enhance drying quality. Full article

A discrete element model of the edible sunflower seed was constructed, addressing the lack of an accurate model for edible sunflower seeds in the simulation process of seeding, cleaning, and transportation, and it was calibrated and verified through actual and simulation tests. Taking the edible sunflower seed as the research object, the range of its simulation parameter values was preliminarily determined through actual tests. Using the seed repose angle as the test index, the simulation parameters of the seed were calibrated through the Plackett—Burman test, the steepest climb test, and the Box–Behnken test. The suspension velocity of the seed model was determined by the Fluent–EDEM coupling simulation test, and the reliability of the discrete element model of the edible sunflower seed was verified. The simulated test results showed that the seed repose angle obtained by the optimization test was 35.823°, which exhibited a relative error of 0.103% in comparison to the average values obtained from the actual test. The simulated suspension velocity of the seed was 6.98 m/s. with a deviation of 0.55 m/s from the average suspension velocity obtained through the actual test. The discrete element model of the edible sunflower seed is accurate and reliable, offering guidance for improving the design of machinery used for seeding and harvesting edible sunflowers. Full article

Rice seed production is a critical step in breeding high-quality varieties. To ensure seed purity, it is essential that no residual grains or broken ears remain in the harvester header after harvesting each variety, thus preventing cross-contamination. This study addresses the issue of seed retention in existing rice harvesters, which lack efficient self-cleaning or other cleaning mechanisms and cannot be cleaned rapidly. A self-cleaning device for the harvester header was designed to enable one-click cleaning after harvesting a single variety. A novel cleaning nozzle was developed as the key component of the device, with its structure optimized through single-factor and orthogonal combination experiments. The number of nozzles was determined based on their spray width and the header width. A header-cleaning airflow simulation model based on Fluent–EDEM coupling was constructed to investigate the effects of nozzle inlet pressure, airflow incident angle, and nozzle outlet height on the self-cleaning rate. Optimal cleaning parameters were identified to maximize the self-cleaning rate, and the simulation results were validated. The study revealed that the nozzle’s expansion section length, throat diameter, and contraction section length significantly affect the spray width. When the expansion section length was 10 mm, the throat diameter was 8 mm, and the contraction section length was 8 mm, the nozzle achieved the largest jet angle, measuring 50.3 cm. Further analysis indicated that inlet air pressure had the greatest influence on the self-cleaning rate, followed by airflow incident angle and nozzle outlet height. The optimal parameter combination was identified as an inlet air pressure of 0.6 Mpa, an airflow incident angle of 118.25°, and a nozzle outlet height of 2.64 mm, achieving a maximum self-cleaning rate of 99.63%. A one-click cleaning system was designed using an STM32 microcontroller and hardware circuits. Field experiments under optimal parameters demonstrated a self-cleaning rate of 97.68% with a cleaning duration of 10 s per cycle. The findings provide theoretical guidance for the design and optimization of self-cleaning headers for rice seed production. Full article

Inner Mongolia has the largest sheep population among China’s provinces, resulting in the production of a substantial amount of sheep manure. If left untreated, this manure can contribute to environmental pollution. However, sheep manure serves a dual purpose: it can be both a pollutant and a valuable source of organic fertilizer. Consequently, there is an urgent need to address the environmental issues arising from manure accumulation and its unused status. In this paper, a viable solution is proposed: the conversion of manure into fertilizer through a composting unit incorporating high-temperature aerobic fermentation technology. This unit, tailored for small farms and individual farmers, integrates critical functions such as ventilation, heating, and turning. Additionally, it boasts excellent thermal insulation, enhancing composting efficiency and enabling precise control over fermentation conditions. This design mitigates heat loss and accelerates maturation, addressing common challenges in traditional composting. The design process encompassed both equipment construction and control systems, with a primary focus on compost fermentation and aeration heating. The components were carefully designed or selected based on theoretical analysis and subsequently validated using simulation software, including EDEM and Fluent. The control system seamlessly integrates a touch screen interface, PLC programming, and control circuits to manage air pumps and electric heaters in response to changes in temperature and oxygen concentration. Furthermore, it controls the motors during the recovery phase. A comprehensive performance evaluation was conducted, revealing notable improvements. Under artificially heated conditions, the maximum temperature of the compost increased by approximately 20 °C, the composting cycle was reduced by roughly 4 days, and the seed germination index (GI) rose by about 9% when compared to natural fermentation. Thus, this device significantly accelerates composting and improves fertilizer quality by increasing the decomposition rate. Full article

Stem mustard, the main raw material for pickled mustard tuber, is widely planted in Chongqing, China, and is an important local cash crop. Under the working conditions of sticky and wet soil in the Chongqing area, conventional furrow seeding has problems such as soil sticking to the furrow opener, poor mulching effect, etc. In this regard, this paper proposes the use of non-contact, soil-based, pneumatic shot seeding, in which seeds are shot into the soil to a predetermined depth by a high-speed air stream. The diameter of stem mustard seeds was found to be 1.33 mm, with a spherical rate of 95.32% using physical and mechanical properties. The high-speed camera test was used to determine the air pressure at the appropriate sowing depth, and the seed entry process was simulated by EDEM 2021 software, which analysed the movement process of the seed after entering the soil, and the structure of the seeder was designed based on the resulting test data. The structural parameters of the shot seeding device were analysed by a hydrodynamic simulation using Fluent 2022 R1 software and the following results were obtained: an outlet pipe diameter D_C of 2 mm, mixing zone length H of 10 mm, mixing zone inlet diameter D of 15 mm, and steady-state gas flow rate of 80 m/s. Simulation seeding verification was conducted on the final determined structural parameters of the seeding device, and the simulation results showed that the seed velocity could reach 32.3 m/s. In actual experiments, it was found that when the vertical velocity of the seeds was greater than or equal to 26.59 m/s, the seeds could be completely and stably seeded into the soil. Therefore, the designed seeding device can meet the conditions of actual seeding experiments. In conclusion, this research offers a practical guideline for the rapid and precise sowing of stem mustard. Full article

The adhesion of dust particles on the surface of the dust collector tends to cause great resistance to the dust collector and affects the operating efficiency. In order to visualize particles in the filtration process and to grasp the mechanism of particle viscosity and sphericity on filtration performance, a numerical simulation study was conducted to investigate the deposition behavior of particles during filtration, employing FLUENT-EDEM coupling technology. By examining the deposition process, the role of particle characteristics on dust behavior within the entire filtration system was elucidated. The effects of varying particle surface energy and particle sphericity on filtration pressure drop and cake porosity were analyzed. The findings reveal that under the force of the air, particles on the surface of the filter membrane experience compaction, leading to a reduction in the porosity of the formed cake layer. The diminution of porosity serves to impede the air, consequently augmenting the pressure drop across the filtration system and hindering the operational efficacy of the dust collector. As the surface energy of the particles increases, the adhesive forces between particles are intensified, leading to an elevation in the porosity of the cake layer and a subsequent decrease in the pressure drop. When the surface energy of the particles is increased from 0.01 J/m² to 0.04 J/m², the porosity experiences a modest increase of only 9.1%, yet the pressure drop is significantly reduced by half, amounting to a decrease of 1594 Pa. Under high particle surface energy, as filtration air velocity increases, particles are compressed, resulting in a decrease in cake porosity and an increase in pressure drop. Concurrently, our findings indicate that as the sphericity of particles increases, their surfaces become increasingly smooth which in turn results in a decreased porosity of the cake layer and, consequently, an elevation in the filtration pressure drop. Full article

The research aims to examine the distribution of porosity and the combined heat and moisture movement while grains are being dried. This research concerns the porosity and flow of soybeans with different particle size ratios and the drying of soybeans with varying particle temperatures. Due to the similarity in shape between soybeans and balls, this article adopts a ball shape to study the heat and moisture transfer of soybean particles, which can also be used for the study of grains with similar shapes, such as mung beans and red beans. Random models of soybeans with varying proportions were created using modeling software Edem and UG. UDF programming was added to the preprocessing software Fluent to analyze the porosity, airstream allocation, and the interaction of temperature and moisture transfer in packed beds with various cylinder-to-particle size ratios and particle temperatures. A packed bed of soybeans was created, and the study examined the impact of cylinder-to-particle size ratios of 4.44, 5.6, and 6.25 on porosity. The results show that the radial porosity in the packed bed displays a fluctuating profile, with partial porosity increasing as the cylinder-to-particle size ratio increases. Increasing the ratio of cylinder size to particle size exacerbated the tortuosity of the flow paths within the packed bed. Simultaneously, the particle temperature increases, leading to a rise in the instantaneous heat transfer during the drying process, strengthening the ratio of moisture transfer within the packed bed. The method effectively models during convective heat and mass transfer in the liquid facies, as well as thermal and mass spread in the solid facies. The results of this study have been validated on physical models. The air temperature of 273 K is considered during the simulation process Full article

To improve the concentration performance of the concentrator in the iron ore beneficiation process for iron ore tailings, a coupled simulation analysis of the concentration process was conducted using the discrete element software EDEM (Engineering Discrete Element Method) and the finite element FLUENT software. The volume concentration at the bottom flow outlet of the concentrator was used as the evaluation index. The scraper rotation speed, feed rate, and feed concentration were considered as parameters. Response surface experiments were designed using the Box-Behnken module in Design Expert11 software, and numerical simulations were performed to obtain data. Based on the numerical simulation results, a prediction model was established using the backpropagation neural network (backpropagation neural network, BP-NN) and combined with the genetic algorithm (genetic algorithm, GA) for parameter optimization of the thickener’s concentration conditions. The results showed that with a scraper rotation speed of 9.7677 rpm, feed rate of 0.2037 m/s, and feed concentration of 6.5268%, the maximum outlet volume concentration reached approximately 62.00%. The predicted optimal working conditions were validated through physical tests and numerical simulations. The average outlet volume concentration in the physical tests was 60.712% (n = 10) (“n” is the number of experiments), with an error of only 2.077% compared to the predicted value. The middle outlet volume concentration in the numerical simulation experiments was 59.951% (n = 10), with an error of only 3.304% from the expected value. These results demonstrate the feasibility of using a genetic neural network for optimizing the EDEM–FLUENT simulation parameters of the thickener, providing valuable insights for the matching optimization of the thickener’s process parameters. Full article

In order to study the working mechanism and sowing effect of seed delivery pipes and their associated cavity seeders, the factors affecting the sowing test were first derived through pressure loss theory and force analysis of cotton seed particles in the gas-solid coupling field. Secondly, Ansys fluent was used to simulate the flow field of seed delivery pipe joints to study the effect of seed delivery pipe joints on the overall pressure loss and uniformity of air pressure distribution and to determine the optimal structure of seed delivery pipe joints. Then, the EDEM was simulated for the overall seed delivery pipe and its associated cavity seeders in the absence of positive pressure to analyze the transport pattern of each cotton seed. Finally, CFD-DEM gas-solid coupling simulation experiments were conducted on the center of two rows of seed delivery pipes and their connected cavity seeders to analyze the trajectory of cotton seeds under different rotational speeds of cavity seeders and different positive seed delivery pressures and to deeply analyze the causes of Multiple seeding and Miss-seeding. At the same time, the seeding performance was evaluated by coupling simulation values with single seeding rate and multiple seeding rate as seeding performance evaluation indexes and compared with bench test. The results show that in the coupling simulation, when the speed of the cavity seeders is 20~40 rev/min and the seed delivery tube is passed into 50~150 Pa positive pressure airflow, the single seeding rate is not less than 83.06%, and the missed seeding rate is not more than 9.23%. In the bench test, the single seeding rate was not less than 80.64%, and the missed seeding rate was not more than 9.86% under the same cavity seeders speed and positive pressure, and the results of the bench test and the simulation test were close and consistent, which verified the feasibility of the simulation. Full article

When using valves and pipes, erosion wear is a major issue. Erosion wear can result in equipment shutdown, material replacement, and other issues, as well as the failure of sealing surfaces. The depth of erosion wear is primarily determined by particle velocity, particle size, target material, and use conditions. A combination of the discrete element method (DEM) and computational fluid dynamics (CFD) was used in this study. The dynamic process of particle collision with the sealing surface is also considered. The wear depth was then calculated using Archard’s abrasive wear theory. The erosion wear process of the graphite-sealing surface by gas-solid two-phase flow medium is numerically simulated in a high-temperature triple eccentric butterfly valve using the above theory and method. The erosion wear patterns of graphite-sealing surfaces were investigated under various particle velocities, particle sizes, target materials, and service conditions. The findings indicate that particle velocity and particle size are positively related to wear rate. Soft target wear depth is greater than hard target wear depth. The wear depth decreases as the ambient temperature rises. As a result, graphite has excellent resistance to erosion and wear at high temperatures. When feeding, however, particle velocity and particle size must be considered. The erosion wears characteristics of a high temperature three eccentric butterfly valve investigated in this paper can be used to optimize erosion wear prevention. Full article

The gas–solid flow of mixed seeds of oat and vetch in the air-blowing venturi tube was simulated numerically by means of a coupling approach of the discrete element method (DEM) and computational fluid dynamics (CFD). In the gas–solid coupling model, EDEM software was used to depict the discrete particle phase, and ANSYS Fluent software was used to describe the continuous gas phase. The effects of the seed entry angle and inlet air velocity on the uniformity of mixed seed supply were studied and analyzed from the angle of airflow field variation and mixed seeds movement characteristics. The simulation results showed that the seeding angle has a great influence on the seed movement in the tube and affects the pressure and velocity gradient of the airflow field. If the seed insertion angle is too large, the number of collisions between the seed and the tube wall will increase, and the phenomenon of seeds retention and disordered jumping will occur. The inlet air velocity mainly affects the outlet air velocity and seed velocity and has little effect on the change in airfield. With the increase in inlet air velocity, the greater the velocity and force of the seeds, the closer the mixed seeds collide with the wall to the outlet pipe. At high inlet airflow velocity, there is a great disparity in the movement speed between the seeds, resulting in uneven spacing between the seeds. The results showed that under the conditions of 60° seed entry angle and 35~40 m/s inlet air velocity, the airflow field distribution in the tube was uniform and the seed movement was continuous and uniform. Full article

Underwater rock-plug blasting is a special blasting technique for excavating underwater inlets. In the process of rock-plug blasting excavation, the blasting-block movement from the difference in water pressure inside and outside the tunnel is one of the key factors for successful construction. Laboratory underwater rock-plug blasting experiments were conducted using small explosive charges, and a high-speed camera was adopted to observe and study block motion. Then, numerical simulations were conducted for the model experiment based on the Fluent and Engineering Discrete Element Method (EDEM) coupling program developed using the user-defined function (UDF) interface to reveal the mechanism underpinning the penetration of underwater rock-plug blasting. The results showed that the process of block motion in underwater rock-plug blasting can be divided into two stages. In the first stage, broken blocks move to two sides along the axis of the rock plug under the blast load. A blasting crater is formed on the downstream end face of the rock plug under the effects of the free face, while the upstream end face is loosened, or blocks are ejected under the influence of the water pressure. In the second stage, blocks flow to the broken-rock pit under the effects of water scouring and gravity, and, finally, the rock plug is penetrated. The larger the head of water and the opening angle of the rock plug are, the better the penetration effect for the rock plug is. The Fluent–EDEM coupling algorithm was in good agreement with the experimental results in terms of the rock-plug blasting effect and the velocity curve of the blocks, indicating that the coupling method had a favorable effect in simulating the interaction of blocks and water during underwater rock-plug blasting. The findings are expected to promote the application and popularization of the rock-plug blasting technique and can provide a reference for rock-plug blasting in water-intake and water-diversion projects. Full article