基于CFD-DEM耦合的不同出口形式气力集排系统分配器仿真与试验

doi:10.12398/j.issn.2096-7217.2024.01.001

摘要/Abstract

摘要：

气力集排技术具有播种效率高、广适性好、种子损伤低等优势，在研究中发现种子分配器的形式和结构参数对气力集排系统排种均匀性影响较大。本研究分别提出了M型、T型和Y型种子分配器，阐述了气力集排系统的总体结构和工作原理，以小麦为研究对象，开展了分配器内种子颗粒群体在气流作用下的受力和运动分析。基于CFD-DEM气固耦合方法，分别建立了小麦种子和分配器的仿真模型，以各行排量均匀性变异系数为指标，开展了不同出口型式对分配器性能影响的仿真试验研究，确定了M型种子分配器为最优结构。在此基础上通过单因素试验研究了不同出口管倾角、顶盖圆锥角、入口直径、圆角半径和气流输送速度对M型种子分配器内部流场均匀性的影响，确定了显著性因素及其水平范围。分别以（出口管倾角、顶盖圆锥角、圆角半径）为因素开展了3因素3水平正交试验研究，以各行排量均匀性变异系数为指标，通过响应面分析，确定了M型种子分配器最优结构参数，在西北农林科技大学试验农场开展了台架和田间验证试验。仿真和试验研究结果表明：与T型和Y型种子分配器相比，M型种子分配器显著提高了小麦种子的排种质量，排种均匀性变异系数分别降低了7.41%和3.72%。当顶盖圆锥角为117.03°，出口管倾角为59.50°圆角半径为69.46 mm时，种子分配器均匀性最佳，各行播种均匀性变异系数为6.05%。M型种子分配器仿真结果与台架和田间试验验证结果的绝对误差分别为1.00%和1.55%。该研究为气力集排系统的设计提供参考和技术支撑。

关键词: 气力集排系统, 种子分配器, CFD-DEM耦合, 田间试验

Abstract:

Pneumatic centralized seeding technology has the advantages of high seeding efficiency， wide adaptability and low seed damage. In the study， it was found that the type and structural parameters of the seed distributor had a great influence on the seeding uniformity of the pneumatic centralized seeding system. In this study， M-type， T-type and Y-type seed distributors were proposed respectively， and the overall structure and working principle of the pneumatic collection system were expounded. Taking wheat as the research object， the force and motion analysis of the seed particle group in the distributor under the action of airflow was carried out. Based on the CFD-DEM gas-solid coupling method， the simulation models of wheat seeds and distributors were established respectively. Taking the coefficient of variation of the uniformity of each row displacement as the index， the simulation test of the influence of different outlet types on the performance of the distributor was carried out， and the M-type seed distributor was determined as the optimal structure. On this basis， the influence of different outlet pipe inclination angles， top cover cone angles， inlet diameters， fillet radius and airflow velocity on the uniformity of the internal flow field of an M-type seed distributor was studied by single factor experiment， and the significant factors and their horizontal range were determined. The orthogonal test of three factors and three levels was carried out with the factors of outlet pipe inclination angle， top cover cone angle and fillet radius. The optimal structural parameters of the M-type seed distributor were determined by response surface analysis with the variation coefficient of uniformity of each row displacement as the index. The bench and field verification tests were carried out on the experimental farm of Northwest A & F University. The simulation and experimental results show that compared with the T-type and Y-type seed distributors， the M-type seed distributor significantly improves the seeding quality of wheat seeds， and the coefficient of variation of seeding uniformity is reduced by 7.41% and 3.72%， respectively. When the cone angle of the top cover is 117.03° and the angle of the outlet pipe is 59.50°， the corner radius is 69.46 mm， the uniformity of the seed distributor is the best， and the coefficient of variation of the uniformity of each row is 6.05%. The absolute errors between the simulation results of the M-type seed distributor and the bench and field test results were 1.00% and 1.55%， respectively. The research provides reference and technical support for the design of a pneumatic collecting and discharging system.

Key words: pneumatic centralized system, seed distributor, CFD-DEM coupling, field experiment

中图分类号:

S223.2

李贵川, 李海宇, 杨少鹏, 黄玉祥, 高筱钧, 付作立. 基于CFD-DEM耦合的不同出口形式气力集排系统分配器仿真与试验[J]. 智能化农业装备学报（中英文）, 2024, 5(1): 1-11.

LI Guichuan, LI Haiyu, YANG Shaopeng, HUANG Yuxiang, GAO Xiaojun, FU Zuoli. Simulation and experiment of distributors of different outlet types of pneumatic collection and discharging systems based on CFD-DEM coupling[J]. Journal of Intelligent Agricultural Mechanization, 2024, 5(1): 1-11.

图/表 17

参考文献 29

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	Item	Details	Index	Value
CFD	Materials	Fluid/air	Density/(kg·m^-3)	1.225
	Materials	Fluid/air	Viscosity/(kg·m^-1·s^-1)	1.789×10^-5
	Boundary conditions	Solid/PLA	Density/(kg·m^-3)	1 250
		Velocity-inlet	Velocity magnitude/(m·s^-1)	28
		Turbulence	Turbulence intensity/%	4
		Turbulence	Hydraulic diameter/mm	50
		Flow-outlet	Outlet type	Flow-outlet
		Wall	Wall motion	Stationary wall
		Wall	Shear condition	No slip
DEM	Materials (wheat seeds)	Particle	overall dimensions/mm	7.01×3.47×3.20
			Thousand-grain weight/g	48.96
			Water content/%	10.80
			Poisson’s ratio	0.41
			Shear modulus/Pa	4.79×10⁷
			Density/(kg·m^-3)	1 350
		wall	Poisson’s ratio	0.35
			Shear modulus/Pa	1.3×10⁹
			Density/(kg·m^-3)	1 250
	Interaction	Particle-particle	Coefficient of restitution	0.47
			Coefficient of static friction	0.55
			Coefficient of rolling friction	0.28
			Interaction contact model	Hertz-Mindlin
		Particle-wall	Coefficient of restitution	0.50
			Coefficient of static friction	0.22
			Coefficient of rolling friction	0.16
			Interaction contact model	Hertz-Mindlin
	Particle	Particle generation	Particle radius/（mm×mm×mm）	7.00×3.20×3.20
			Factory type	Dynamic/unlimited number
			Generation rate/（s^-1）	2 000

	Item	Details	Index	Value
CFD	Materials	Fluid/air	Density/(kg·m^-3)	1.225
	Materials	Fluid/air	Viscosity/(kg·m^-1·s^-1)	1.789×10^-5
	Boundary conditions	Solid/PLA	Density/(kg·m^-3)	1 250
		Velocity-inlet	Velocity magnitude/(m·s^-1)	28
		Turbulence	Turbulence intensity/%	4
		Turbulence	Hydraulic diameter/mm	50
		Flow-outlet	Outlet type	Flow-outlet
		Wall	Wall motion	Stationary wall
		Wall	Shear condition	No slip
DEM	Materials (wheat seeds)	Particle	overall dimensions/mm	7.01×3.47×3.20
			Thousand-grain weight/g	48.96
			Water content/%	10.80
			Poisson’s ratio	0.41
			Shear modulus/Pa	4.79×10⁷
			Density/(kg·m^-3)	1 350
		wall	Poisson’s ratio	0.35
			Shear modulus/Pa	1.3×10⁹
			Density/(kg·m^-3)	1 250
	Interaction	Particle-particle	Coefficient of restitution	0.47
			Coefficient of static friction	0.55
			Coefficient of rolling friction	0.28
			Interaction contact model	Hertz-Mindlin
		Particle-wall	Coefficient of restitution	0.50
			Coefficient of static friction	0.22
			Coefficient of rolling friction	0.16
			Interaction contact model	Hertz-Mindlin
	Particle	Particle generation	Particle radius/（mm×mm×mm）	7.00×3.20×3.20
			Factory type	Dynamic/unlimited number
			Generation rate/（s^-1）	2 000

Factors	Level
The inclination of outlet pipe θ₁/(°)	50, 55, 60, 65, 70
The cone angle of the top cover θ₂/(°)	100, 120, 140, 160, 180
The inlet diameter D_r/mm	56, 58, 60, 62, 64
The fillet radius R/mm	62, 66, 70, 74, 78
The pneumatic conveying speed V_c/(m·s^-1)	28, 30, 32, 34, 36

Factors	Level
The inclination of outlet pipe θ₁/(°)	50, 55, 60, 65, 70
The cone angle of the top cover θ₂/(°)	100, 120, 140, 160, 180
The inlet diameter D_r/mm	56, 58, 60, 62, 64
The fillet radius R/mm	62, 66, 70, 74, 78
The pneumatic conveying speed V_c/(m·s^-1)	28, 30, 32, 34, 36

Level	The inclination angle θ₁/(°)	The cone angle θ₂/(°)	The fillet radius R/mm
-1	55	100	66
0	60	120	70
1	65	140	74