白萝卜种子颗粒模型离散元接触参数标定与试验

doi:10.13304/j.nykjdb.2021.0363

摘要/Abstract

摘要：

在利用EDEM与FLUENT耦合模拟白萝卜排种器排种过程时，白萝卜种子颗粒参数设置以及模型的选择直接影响仿真结果的可靠性。结合白萝卜种子真实颗粒和仿真堆积试验，标定了不同填充球颗粒半径白萝卜种子模型的2个主要接触参数：白萝卜种子-有机玻璃静摩擦系数和白萝卜种子间静摩擦系数。采用自动填充方式创建了不同填充球颗粒半径白萝卜种子的离散元模型。利用Plackett-Burman试验对物料特性影响参数进行分析，发现白萝卜种子-有机玻璃静摩擦系数、白萝卜种间静摩擦系数对堆积角的影响极显著。结合台架与仿真堆积试验，建立了2个主要接触参数与堆积角的二元回归模型，以白萝卜种子实际堆积角为目标对参数进行寻优，得到不同填充球颗粒半径白萝卜种子模型的白萝卜种子-有机玻璃静摩擦系数和白萝卜种子间静摩擦系数。结合堆积角相对误差率与仿真时间分析最佳球颗粒填充半径，当白萝卜种子离散元填充颗粒半径为0.25 mm时，其仿真精度和仿真时间最优。得到的最佳填充球颗粒模型以及标定的接触参数，为白萝卜种子排种器研究提供一定的参考。

关键词: 填充颗粒半径, 离散元法, 白萝卜种子, 参数标定

Abstract:

When using EDEM and FLUENT to simulate the seeding process of radish seed metering device， the parameters and the model of radish seed directly affect the reliability of the simulation results. 2 main contact parameters of white radish seed-organic glass static friction and inter-seed static friction were calibrated according to the actual and simulated packing experiment of white radish seed. In this paper， the discrete element models of radish particles with different filling diameters were established by using the automatic filling method. Plackett-Burman test was used to analyze the influence parameters of material characteristics. The results showed that the static friction of white radish seed-organic glass and the static friction of white radish seed-organic glass had significant effect on the stacking angle. Based on the bench test and the simulation stacking test， the binary regression model of 2 main contact parameters and stacking angle was established， the static friction coefficient between seeds and organic glass and the static friction coefficient between seeds of turnip with different filling radius were obtained. According to the relative error rate of stacking angle and the simulation time， the best filling radius of spherical particles was analyzed. The results showed that when the filling radius of radish seed dem was 0.25 mm， the simulation precision and the simulation time were the best. The best model of filling pellet and the calibrated contact parameters could provide some references for the related research of seed metering device of white radish.

Key words: filling particle radius, discrete element method, radish seed, parameter calibration

中图分类号:

S223.2

闫建伟, 魏松, 胡冬军, 刘启合, 张富贵. 白萝卜种子颗粒模型离散元接触参数标定与试验[J]. 中国农业科技导报, 2022, 24(5): 119-128.

Jianwei YAN, Song WEI, Dongjun HU, Qihe LIU, Fuigui ZHANG. Parameter Calibration of Radish Seeds with Different Filling Particle Radius by DEM[J]. Journal of Agricultural Science and Technology, 2022, 24(5): 119-128.

图/表 17

图1 测量装置

Fig. 1 Measurement device

图2 白萝卜种子轮廓模型

Fig. 2 Radish seed contour model

表1 仿真试验参数

Table 1 Parameter in simulation experiment

参数

Parameter

数值

Value

白萝卜种子泊松比

White radish seeds poisson's ratio

0.36

白萝卜种子剪切模量

Shear modulus of radish seed/Pa

1.43×10⁷

白萝卜种子的密度

Density of white radish seeds/（kg·m^-3）

1 100

有机玻璃泊松比

Perspex poisson ratio

0.5

有机玻璃剪切模量/Pa

Shear modulus of perspex/Pa

1.77×10⁸

有机玻璃密度/（kg·m^-3）

Density of perspex/ （kg·m^-3）

1 180

白萝卜种子-有机玻璃碰撞系数

Collision coefficient of turnip seed-perspex

0.25~0.50

白萝卜种子-有机玻璃静摩擦系数

Static friction coefficient of turnip seed-perspex

0.20~0.60

白萝卜种子-有机玻璃滚动摩擦系数

Coefficient of rolling friction of turnip seed-perspex

0.005~0.020

白萝卜种子-白萝卜种子碰撞系数

Collision coefficient of white radish seed-white radish seed

0.10~0.30

白萝卜种子-白萝卜种子静摩擦系数

Static friction coefficient of white radish seed-white radish seed

0.20~0.60

白萝卜种子-白萝卜种子滚动摩擦系数

Coefficient of rolling friction of white radish seed-white radish

0.005~0.030

表2 Plackett-Burman 试验参数

Table 2 Parameter of Plackett-Burman test

参数 Parameter	水平 Level
参数 Parameter	-1	1
x₁：白萝卜种子-有机玻璃碰撞系数 Collision coefficient of turnip seed-perspex	0.250	0.500
x₂：白萝卜种子-有机玻璃静摩擦系数 Static friction coefficient of turnip seed-perspex	0.200	0.400
x₃：白萝卜种子-有机玻璃滚动摩擦系数 Coefficient of rolling friction of turnip seed-organic glas	0.005	0.010
x₄：白萝卜种子-白萝卜种子碰撞系数 Collision coefficient of white radish seed-white radish seed	0.100	0.200
x₅：白萝卜种子-白萝卜种子静摩擦系数 Static friction coefficient of white radish seed-white radish seed	0.200	0.400
x₆：白萝卜种子-白萝卜种子滚动摩擦系数 Coefficient of rolling friction of white radish seed-white radish	0.005	0.010

表3 Box-Behnken试验因素编码

Table 3 Factors and codes of Box-Behnken test

水平

Level

x₂：白萝卜种子-有机玻璃静摩擦系数

Static friction coefficient of turnip seed-perspex

x₅：白萝卜种子-白萝卜种子静摩擦系数

Static friction coefficient of white radish seed-white radish seed

图3 不同半径球形颗粒填充的白萝卜种子模型

Fig. 3 Radish seed model filled with spherical particles with different radius

表4 白萝卜种子仿真模型对应填充球半径与数量

Table 4 Radius and quantity of filling balls corresponding to white radish seed simulation model

半径 Radius/mm	数量 Number
0.10	2 461
0.15	728
0.20	298
0.25	155
0.30	79
0.35	56

图4 不同填充球半径的白萝卜种子离散元模型

Fig. 4 Discrete element model of radish with different radius of filling ball

图5 堆积角图像处理

Fig. 5 Image processing of natural stacking angle in experiment

表5 堆积角测量结果

Table 5 Measurement results of natural stacking angle

试验 Test	θ：堆积角 Accumulation angle /（°）
T1	26.96
T2	27.54
T3	27.87
T4	28.21
T5	28.82
平均Mean	27.88

图6 模拟堆积角图像处理

Fig.6 Image processing of response angle in simulation

表6 Plackett-Burman试验设计及结果

Table 6 Design and results of Plackett-Burman test

序号 Code	x₁	x₂	x₃	x₄	x₅	x₆	θ：堆积角 Accumulation angle/（°）
1	1	1	-1	-1	-1	1	26.81
2	-1	-1	-1	-1	-1	-1	32.91
3	1	1	1	-1	-1	-1	27.71
4	1	1	-1	1	1	1	23.46
5	1	-1	1	1	-1	1	30.16
6	-1	1	1	1	-1	-1	28.59
7	1	-1	-1	-1	1	-1	25.83
8	-1	1	1	-1	1	1	20.71
9	-1	1	-1	1	1	-1	26.46
10	-1	-1	1	-1	1	1	24.07
11	1	-1	1	1	1	-1	27.68
12	-1	-1	-1	1	-1	1	29.93

表7 参数显著性分析

Table 7 Analysis of parameters of significance

参数 Parameter	效应 Effect	均方和 Sum of mean square	$F$	$P$
模型Model	—	114.17	18.33	0.002 9^**
x₁	-0.17	0.087	0.084	0.784 2
x₂	-2.81	23.63	22.76	0.005 0^**
x₃	-1.08	3.50	3.37	0.125 8
x₄	1.37	5.66	5.45	0.066 8
x₅	-4.65	64.87	62.48	0.000 5^**
x₆	-2.34	16.43	15.82	0.010 6^*

表7 参数显著性分析

Table 7 Analysis of parameters of significance

参数 Parameter	效应 Effect	均方和 Sum of mean square	$F$	$P$
模型Model	—	114.17	18.33	0.002 9^**
x₁	-0.17	0.087	0.084	0.784 2
x₂	-2.81	23.63	22.76	0.005 0^**
x₃	-1.08	3.50	3.37	0.125 8
x₄	1.37	5.66	5.45	0.066 8
x₅	-4.65	64.87	62.48	0.000 5^**
x₆	-2.34	16.43	15.82	0.010 6^*

表8 Box-Behnken试验设计及结果

Table 8 Design and results of Box-Behnken test

序号 Code	x₂	x₅	θ'：堆积角 Accumulation angle/（°）
1	0	-1	26.95
2	0	0	28.48
3	0	0	27.98
4	1	1	32.08
5	1	0	29.95
6	1	-1	28.58
7	0	0	27.55
8	0	0	28.05
9	-1	1	28.32
10	1	0	29.85
11	0	1	30.02
12	0	0	28.10
13	0	1	29.88
14	0	-1	27.82
15	-1	0	25.71
16	-1	-1	23.70
17	-1	0	26.10

表9 Box-Behnken二次回归模型方差分析

Table 9 Anova of modified model of Box-Behnken

方差来源 Source of variance	均方和 Sum of squares	自由度 Degree of freedom	平方和 Mean square	F	P
模型	58.05	5	11.61	57.46	<0.000 1^**
x₂	34.57	1	34.57	171.07	<0.000 1^**
x₅	21.95	1	21.95	108.60	<0.000 1^**
x₂x₅	0.31	1	0.31	1.55	0.238 7
x₂²	0.39	1	0.39	1.93	0.192 4
x₅⁵	0.90	1	0.90	4.44	0.058 8
残差Residual	2.22	11	0.20	—	—
失拟Lack of fit	1.31	3	0.44	3.85	0.056 6
误差Pure error	0.91	8	0.11	—	—
总和Cor total	60.28	16	—	—	—
R²=0.963 1	R²_Adj=0.946 4	CV=1.60%	A_P=27.971

表10 不同填充半径白萝卜种子离散元模型标定接触参数结果

Table 10 Calibration of contact parameters of radish with different filling radius using discrete element model

填充颗粒半径 Filling radius/mm	x₂：白萝卜种子-有机玻璃静摩擦系数 Static friction coefficient of turnip seed-perspex	x₅：白萝卜种子-白萝卜种子静摩擦系数 Static friction coefficient of white radish seed-white radish seed
0.35	0.57	0.55
0.30	0.53	0.39
0.25	0.49	0.36
0.20	0.47	0.36
0.15	0.46	0.35
0.10	0.44	0.33

表11 不同填充半径颗粒离散元模型仿真与真实试验结果

Table 11 Simulation and real test results of particle discrete element model with different filling radius

填充半径 Fill radius/mm	堆积角平均值 Accumulation angle average/（°）	相对误差率 Relative error rate/%	仿真时间 Simulation time/h
0.35	33.50	20.16	3.86
0.30	31.81	14.10	4.94
0.25	28.86	3.51	7.66
0.20	28.24	1.29	10.96
0.15	28.35	1.69	18.65
0.10	28.04	0.57	35.63

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