Discrete Particle Simulation of Gas-Solid Flow in Air-Blowing Seed Metering Device

In this paper,the gas and seed flow characters in the air-blowing seed metering device are investigated by using the coupled computational fluid dynamics and discrete element method(CFD-DEM)in three dimensions(3D).The method of establishing boundary model based on the computer-aided design(CAD)drawing,has been used to build the boundary model of seed metering device.The 3D laser scanning technique and multi-element method are adopted to establish the particle model.Through a combined numerical and experimental effort,using 3D CFD-DEM software,which is based on the in-house codes,the mechanisms governing the gas and solid dynamic behaviors in the seed metering device have been studied.The gas velocity field and the effect of different rotational speeds and air pressures on the seeding performance and particle velocity have been studied,similar agreements between numerical and experimental results are gained.This reveals that the 3D CFD-DEM model established is able to predict the performance of the air-blowing seed metering device.It can be used to design and optimize the air-blowing seed metering device and other similar agriculture devices.

Design and experiment of the pneumatic double disc precision seed metering device for Chinese flowering cabbage

Single seed metering devices for Chinese flowering cabbage planting machines have suffered such deficiencies as low efficiency,poor accuracy,and instability.To overcome these limitations,a pneumatic double disc precision seed metering device was designed.This innovative device can simultaneously plant four rows,considering the specific agricultural requirements and the geometric characteristics for Chinese flowering cabbage seeds.The precise parameters of the key component seed disc were derived through theoretical calculation.In addition,a detailed account was given for the working principle and workflow of the seed metering device.The discrete element method and EDEM software were employed to optimize the seed disc by exploring the effects of seed disc rotational speed and interleaving seed slots on seed viability.Orthogonal rotation experiments were conducted to evaluate the impact of seed disc rotational speed and negative pressure.While rates of qualified seeding,double seeding and missing seeding were adopted as test indicators.Testing results show that,at a seed disc rotational speed of 41.5 r/min and a negative pressure of 3.80 kPa,the average qualified seeding rate is 90.13%,the average missing seeding rate is 3.30%,and the average double seeding rate is 6.02%.These values satisfy the agricultural requirements for planting Chinese flowering cabbage.The findings can also provide valuable insights for the structural optimization and design of precision seed metering devices for Chinese flowering cabbage.

Design and indoor simulated experiment of pneumatic rice seed metering device

In order to meet the agronomy demand for hybrid rice direct seeding,a novel precise pneumatic rice seed metering device was designed with groups of sucking holes plate,by which 3-4 seeds could be synchronously sucked and synchronously dropped into the paddy field.The plate was divided into five sections:seed sucking,seed clearing,seed carrying,seed dropping,and blank sections.The seeds were sucked in sucking section by the vacuum,carried and rotated to the dropping section with the plate,blown away in dropping section by the positive pressure air,and thrown into the dropping tube.The influences of the hole diameter,vacuum degree,and clear-up equipment on precision of metering device were discussed.Experiments were conducted to investigate the seeding precision and simulate the field emergence rates on the indoor seeding test-bed.The subjects were pregnant Indic hybrid Peizataifeng under two kinds of moisture content(23.43%and 26.07%).Other experiment conditions included the vacuum degree of 2.60 kPa,the rotation speed of seed sucking plate of 30 r/min,three sucking holes with a diameter of 1.6 mm,and the seed layer thickness of 25 mm.The seeding results showed that,in condition of no more than two seeds per hill,the emergence probabilities under the two moisture contents were 11.82%and 11.95%,respectively,and in condition of 3-4 seeds per hill,the results were 64.81%and 65.84%,respectively.With 2-5 seeds per hill,the results were 92.08%and 92.60%,respectively.If the emergence probability was 80%,under the two moisture contents,the no seed per hill probabilities were 1.33%and 0.80%respectively;the probabilities with 3-4 seeds per hill were 56.13%and 56.40%respectively;the probabilities with 5 or more seeds per hill were 10.67%and 10.13%respectively;the probabilities with 2-5 seeds per hill were 87.60%and 88.13%respectively.The results showed the simulated experiment was an efficient and economic method to assess the capability of pneumatic rice seed drilling metering device,and the precise pneumatic rice seed drilling metering device had a good prospect in practical application.

Optimization design and experiment on ripple surface type pickup finger of precision maize seed metering device

A ripple surface type pickup finger was designed to improve the performance of pickup finger precision maize seed metering device and to provide a solution for precision maize planter.The main structure and working principle of seed metering device were detailed in this paper.The dimension size distributions of maize seeds in different types were studied,the gestures of seeds clamped by pickup finger were analyzed,and the clamping dynamical model of pickup finger was established by theoretical analysis.To optimize the structural parameters of ripple surface type pickup finger,the discrete element method(DEM)model of pickup finger precision maize seed metering device was established by the discrete element software EDEM.The numerical simulations of orthogonal seeding performance experiments were conducted to analyze the influences of these factors on the quality of seeding.The rotational speed,wavelength of ripple surface and amplitude of ripple surface were selected as the experimental factors.The average seeding qualified index and the average seeding coefficient of variation on four different types of maize seeds were chosen for evaluating the seeding performance.The results showed that,the average seeding qualified index was 93.35%and the average seeding coefficient of variation was 11.23%under conditions of the 25 r/min rotational speed,8 mm wavelength of ripple surface and 2 mm amplitude of ripple surface.Under the same condition,the bench test was done which showed that the results of test and simulation were consistent.The maximum error of qualified index was 1.95%and the qualified index of improved seed metering device exceeded the original one by 12.34%.The working performance can meet the requirements of precision maize seeding.

Design and key parameter optimization of an agitated soybean seed metering device with horizontal seed filling

Since the low seed filling speed of mechanical seed metering devices reduces the low qualified rate of seed spacing during high-speed practices,it is significant to design agitated seed metering devices with horizontal seed filling that are suitable for high-speed practices.The combination of horizontal seed filling and agitated seed filling can accelerate the seed filling of mechanical seed metering devices,and improve the qualified rate of seed spacing during high-speed practices.In this study,theoretical analysis,discrete element method-based simulation and indoor bench test verification were conducted to investigate how key parameters of the agitated seed metering device with horizontal seed filling(angles,installation position and number of agitating plates,diameters of convex spoons)would affect the characteristics of soybean seed movement,seed number and seeding performance(qualified index,multiple index,missing seeding index)under different working speeds.Computer-based simulation,test design and regression analysis were combined to analyze the population moving rules and optimize the design parameters of seed metering devices.Based on the test scheme as designed,simulations were conducted on Fluent EDEM,and the optimal angle of the agitating plates was determined by analyzing the population migrating rules.Regression equations were established through the regression of test results,and used to find out the optimal design parameters(diameter of convex spoon,positions and number of agitating plates)of seed metering devices.Then the optimal parameter combination among different working conditions was determined that the angle,position and number of agitating plates were 30°,24.4 mm,and 13,respectively,and the diameter of convex spoon was 11.0 mm.With the optimal parameter combination and at the seeding speed of 12 km/h,the qualified index,multiple index and missing seeding index were 93.1%,2.1%and 4.8%,respectively.Under high-speed practices,the new seed metering device was not significantly different from the pneumatic seed metering device,but significantly outperformed the mechanical seed metering device.

Design and experiment of an air-suction potato seed metering device

An air-suction potato seed metering device was designed to improve the performance of the large-size seed crops planting equipment and provide a solution for problems on the mechanical potato seeder,such as high multiple-seeding index,high missing-seeding index,low qualified index,and limited versatility.The main structure and operation parameters in terms of rotating speed of the device,seeds height and pickup vacuum pressure were determined by theoretical analysis.Two orthogonal tests,conventional tuber(the triaxial average diameter is about 38-57 mm)test and mini-tuber(the triaxial average diameter is about 12-36 mm)test,were conducted to analyze the influences of these factors on the quality of seeding.The multiple-seeding index,missing-seeding index and qualified index were chosen for evaluating the working performance.The results of conventional tuber test showed that,the multiple-seeding index was 1.1%,the missing-seeding index was 0.8%and the qualified index was 98.1%under conditions of the 30 r/min rotating speed,25 cm seeds height and 10 kPa pickup vacuum pressure.The results of mini-tuber test showed that the multiple-seeding index was 0.5%,the missing-seeding index was 0.6%and the qualified index was 98.9%under conditions of 35 r/min rotating speed,17 cm seeds height and 3.5 kPa pickup vacuum.The working performances of the device can meet the requirements of precision seeding.

Design of an active seed throwing and cleaning unit for pneumatic rice seed metering device

To address the clogging of the rice seed metering device after a long period of operation without affecting the precision of normal seeding,an active seed throwing and cleaning unit was designed based on the fact that magnets of the same pole were mutually exclusive.The working principle of the two devices was analysed theoretically,and a mechanical model was created according to the relationship between the repulsion forces of magnets and the spring forces of springs.The super hybrid rice Y-2 You 900 with 22.5%moisture content(wet basis)was used as the test object.The whole factor experiments were carried out under different negative pressures,rotational speeds of the suction plates,and lengths of probes.The results indicated that under any test conditions,the active seed throwing and cleaning unit worked normally.The results of high-speed photography showed that the rate of seed cleaning was 100%.The results also showed that the optimal negative pressure was 0.8 kPa.The probability of 1-3 seeds per hill for the seed metering device was approximately 95%under the optimal negative pressure.The optimal length of the probe was found to be 2 mm.The average qualified rate of hill space was 96.04%under the optimal length of probe,the longer the length of the probe,the lower the qualified rate of hill space.It also showed that an active seed throwing and cleaning unit could effectively avoid the hole clogging caused by the long-term operation and had no influence on the normal operation of the pneumatic rice seed metering device.The active seed throwing and cleaning unit improved the stability of the seed metering device,and the research provided a reference for the optimal design of seed throwing and cleaning structures of the pneumatic rice seed metering device.

Design and experiment of the double-seed hole seeding precision seed metering device for peanuts

A secondary seeding precision double-seed peanut hole seeding seed metering device was designed to improve the performance of the peanut planting equipment and provide a solution for problems on the high seed charge that can cause poor cavitation and uniformity easily.The main structure and operation parameters in terms of groove length,seed charge height,seed-bed belt speed,and rotation speed of the seed metering wheel were determined through theoretical analysis.Single-factor and orthogonal tests were carried out through the JPS-12 seed metering device test bench,and the peanut variety Jinonghua-3 was selected as the test object.The single hole double-seed rate,qualified rate,the variation coefficient of hole spacing,and hole rate were chosen for evaluating the working performance.The results of the single-factor test showed that the seed metering performance is mainly affected by the groove length,the speed of the seed-bed belt and the rotation speed of the seed metering wheel,and the influence of the cavitation rate is minimal.The optimal seeding height is determined to be 40 mm.The results of the orthogonal test showed that the groove length was 27.3 mm,the seed-bed belt speed was 1.51 km/h,and the rotation speed of the seed metering wheel was 14.11 r/min.What’s more,a regression model based on the orthogonal test results was established,the qualified rate of the number of holes obtained after optimizing the model was 98.84%,the variation coefficient of hole spacing was 9.74%,and the hole rate was 1.40%.Notably,the working performances of the device can meet the requirement of precision seeding.

Optimizing the seed-cell filling performance of an inclined plate seed metering device using integrated ANN-PSO approach

Uniformseed distribution within the row is the prime objective of precision planters for better crop growth and yield.Inclined plate planters are generally used for sowing bold seeds likemaize,groundnut,chickpea,and their operating parameters like the forward speed of operation,the seedmetering plate inclination,and the seed level in the hopper affect the cell fill and subsequently the uniformseed distribution.Therefore,to achieve precise seed distribution,these parameters need to be optimized.In the present study,out of the different optimization techniques,a new intelligent optimization technique based on the integrated ANN-PSO approach has been used to achieve the set goal.A 3–5-1 artificial neural network(ANN)model was developed for predicting the cell fill of inclined plate seedmetering device,and the particle swarmoptimization(PSO)algorithmwas applied to obtain the optimum values of the operating parameters corresponding to 100%cell fill.The most appropriate optimal values of the forward speed of operation,the seed metering plate inclination,and the seed level in the hopper for achieving 100%cell fill were found to be 3 km/h,50-degree,and 75%of total height,respectively.The proposed integrated ANN-PSO approach was capable of predicting the optimal values of operating parameters with amaximumdeviation of 2%compared to the experimental results,thus confirmed the reliability of the proposed optimization technique.

Study on positive-negative pressure seed metering device for wide-seedling-strip-seeding

In order to solve the problem of poor uniformity of wheat strip sowing,this paper designs a positive-negative pressure wheat wide-seedling-strip-seeding precision seed metering device,which adopts the roller structure with the principle of combined positive-negative pressure.Through theoretical analysis and relevant data,the structure of the seed metering device and the structure of the positive-negative pressure air chamber were designed.The internal flow field conditions were simulated by Fluent software under different structural parameters.The design of the seed holes was completed by analyzing the pressure cloud diagram and the flow velocity vector diagram,and the optimal combination of parameters was obtained and the influence law of negative pressure on the flow field was obtained.The effect of rotational speed on the flow field was studied by EDEM-Fluent coupling technique.In this paper,a three-factor and three-level response surface test was conducted on a JPS-12 test bench with Liangxin-99 wheat as the research object.The experiment was conducted with the rotational speed of seed metering device,the negative pressure of seed suction and the seeding height as factors,and the qualified index,the reseeding index and the miss-seeding index as evaluation indicators.Through the test,the optimal structure and working parameters of the seed metering device were determined as follows:the diameter of the seed hole was 2 mm,and the number of seed holes per row was 28,negative pressure was−3.5 kPa,rotational speed of seed metering device was 19 r/min,and seeding height was 180 mm.Validation test was carried out on the optimized seed metering device:the qualified index was 80.62%,the reseeding index was 9.22%,and the miss-seeding index was 10.16%,which reached the parameter indicator in JB/T 10293-2013 Technical conditions of single seed(precision)seeder and met the agronomic requirements for wheat wide-seedling-strip-seeding.