Journal of Jilin University(Engineering and Technology Edition) ›› 2025, Vol. 55 ›› Issue (9): 2913-2925.doi: 10.13229/j.cnki.jdxbgxb.20240293

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Self⁃similar characteristics of particle velocity and volume fraction distribution in eccentric hopper

Jian-hua FAN1(),Liang ZHANG1,Hong-wei WANG1,Lei ZHANG2,Jian-qun YU3   

  1. 1.College of Mechanical and Aerospace Engineering,Jilin University,Changchun 130022,China
    2.Institute of Mechanical and Electrical Technology,Jilin Provincial Agricultural Machinery Research Institute,Changchun 130022,China
    3.College of Biological and Agricultural Engineering,Jilin University,Changchun 130022,China
  • Received:2024-03-22 Online:2025-09-01 Published:2025-11-14

Abstract:

Based on the discrete element method, the flow characteristics of granular matter through eccentric hopper outlet driven by gravity were numerically investigated. Two different eccentricities e (distance between the center of the hopper and the center of the outlet) and s (distance between the left wall of the hopper and the left end of the hopper outlet) were used to characterize the discharge process of the eccentric hopper, the influence of the eccentricities on the distribution of particle velocity and volume fraction at the orifice was systematically studied. The results show that for different outlet sizes, when the eccentricity e is used to characterize the discharge process, the granular flow exhibits different flow patterns, while the discharge flow patterns are similar when the eccentricity variable s is used. Further, according to the analysis of eccentricity s, the distribution of particle velocity and volume fraction have self-similar characteristics, their normalized contour curves can be well described by the exponential function, and the exponential parameter determines the trend of curve contour change, which has clear physical significance. Combining the profiles of particle velocity and volume fraction, a normalized formula for predicting flow rate of rectangular eccentric hopper is proposed. It is found that it has the maximum discharge rate when the outlet is located at the wall of the hopper (s=0). At the microscopic scale, understanding the dynamic characteristics and physical laws of the particle discharging is helpful to optimize the structure of the hopper and particle flow, as well as accurately predict the discharge rate.

Key words: agricultural engineering, particle velocity distribution, volume fraction distribution, discharge rate prediction, discrete element method

CLC Number: 

  • S126

Fig.1

Model diagram of eccentric hopper"

Table 1

Parameters in the simulations"

类型参数数值
颗粒参数颗粒数N3 000
颗粒直径d/mm3
颗粒密度ρp/(kg·m-32 500
泊松比ν0.25
剪切模量G/Pa1×108
颗粒接触参数颗粒-颗粒滑动摩擦因数μp,p0.5
颗粒-颗粒滚动摩擦因数μr?p,p0.01
颗粒-颗粒碰撞恢复因数ep,p0.2
颗粒-料斗壁面滑动摩擦因数μp,w0.5
颗粒-料斗壁面滚动摩擦因数μr?p,w0.01
颗粒-料斗壁面碰撞恢复因数ep,w0.2
料斗几何参数宽度L/mm100
出口尺寸D/mm18, 30, 45, 60
高度H/mm300
偏心量e/mm0, 3, 27
偏心量s/mm0, 6, 12, 18, 24, 30

Fig.2

Hopper discharge process and particle flow velocity distribution"

Fig.3

e and s eccentricity variables characterize the particle flow velocity vector map"

Fig.4

Schematic of particle velocity and volume fraction measurement"

Fig.5

Eccentricity variable e characterizes the particle velocity profile"

Table 2

Fitting parameters of particle velocity distribution and volume fraction distribution of eccentric variable e"

e/mmεmn
01.2660.390.386
31.2580.390.393
271.3890.390.418

Fig.6

Eccentricity variable e characterizes particle volume fraction distribution"

Fig.7

Hopper mass flow rate (D/d=20) as a function of particle-wall friction coefficient and wall thickness, and plots of particle volume fraction index versus Z, and μp,w"

Fig.8

Eccentricity variable s characterizes the particle velocity distribution"

Table 3

Fitting parameters of particle velocity distribution and volume fraction distribution of eccentric variable s"

s/mmα1α2β1β2ab
0-0.311-0.1301.46210.2780.32
12-0.056-0.0071.31210.3710.42
30-0.0240.0021.26910.3830.41

Fig.9

Relationship between parameters α1 and a and the dimensionless number of eccentricity variables 2s?/L-D"

Fig.10

Eccentricity variable s characterizes the particle volume fraction distribution"

Fig.11

Variation of parameters α2 and b with the dimensionless number of eccentricity variables 2s?/L-D"

Fig.12

Normalized mass flow rate versus eccentricity variable dimensionless 2s?/L-D for different hopper outlets"

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