Calibration of Discrete Element Simulation Parameters for Powder Screw Conveying

In order to obtain the accurate contact parameters in the simulation process of powder screw conveying, this paper took wheat flour as an example, based on the discrete element JKR (Johnson-Kendall-Roberts) contact model, and directly calibrated the simulation contact parameters in the process of screw conveying in response to the mass flow rate of wheat flour. Firstly, the simulation density of wheat flour particles was calibrated, and the simulation density of wheat flour particles was 1320 kg/m. Then, Plackett-Burman experiment was used to screen out the parameters that had significant influence on the mass flow rate: surface energy JKR, coefficient of static friction between wheat flour and wheat flour, and the coefficient of static friction between wheat flour and stainless steel. The second-order regression model of mass flow rate and significance parameters was established and optimized based on Box-Behnken experiment, and the optimal combination of significance parameters: JKR was obtained to be 0.364; the static friction coefficient of wheat flour to wheat flour was 0.437; and the static friction coefficient of wheat flour to stainless steel was 0.609. Finally, the calibration parameters were used for simulation. By comparing the mass flow rate of simulation and experiment, the relative error of the two was 1.37%. The simulation and experiment flow rate values at different rotating speeds (60 r/min, 80 r/min, 100 r/min, 120 r/min, and 140 r/min) were further compared, and the errors were all within 3%. The method of directly calibrating the simulation contact parameters through the screw conveying process can improve the accuracy of screw conveying simulation, and providing a method and basis for powder contact parameters calibration and screw conveying simulation of wheat flour.

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CONSTRUCTION OF A DISCRETE ELEMENT MODEL OF BUCKWHEAT SEEDS AND CALIBRATION OF PARAMETERS

INMATEH Agricultural Engineering ◽

10.35633/inmateh-64-17 ◽

2021 ◽

pp. 175-184

Author(s):

Bing Xu ◽

Yanqing Zhang ◽

Qingliang Cui ◽

Shaobo Ye ◽

Fan Zhao

Keyword(s):

Stainless Steel ◽

Friction Coefficient ◽

Static Friction ◽

Discrete Element ◽

Rolling Friction ◽

Restitution Coefficient ◽

Steel Rolling ◽

Static Friction Coefficient ◽

Contact Parameters ◽

Rolling Friction Coefficient

In view of the lack of seeds contact parameters that can be used as a reference for the design of key mechanical components such as buckwheat planting, harvesting, and processing, this study combines simulation optimization design experiments and physical experiments to calibrate the parameters of simulated discrete element of buckwheat seeds. The non-spherical particle model of buckwheat seeds was established using the automatic filling method, and the simulation accumulating test and physical accumulating test were carried out using the bottomless conical cylinder lifting method; the repose angle of buckwheat seeds was taken as the response value, and the initial parameters were screened for significance based on the Plackett-Burman test; and a second-order regression model of the error value for the repose angle and the significance parameter was established based on the steepest climb test and Box-Behnken test. On this basis, the minimum error value of the repose angle was used as the goal to optimize the significance parameter, the optimal combination of contact parameters was obtained, and parameter validation tests were carried out. The significance screening test showed that the buckwheat-buckwheat static friction coefficient, the buckwheat-stainless steel rolling friction coefficient, and the buckwheat-stainless steel restitution coefficient had significant effects on the repose angle of buckwheat (P<0.05). The optimization test showed that the buckwheat-buckwheat static friction coefficient was 0.510, the buckwheat-stainless steel rolling friction coefficient was 0.053, and the buckwheat-stainless steel restitution coefficient was 0.492. The validation test showed that the repose angle of buckwheat seeds under such parameter was 25.39°, and the error with the repose angle of the physical test was 0.55%, which indicated that the optimal parameter combination was reliable. This study could provide a seed model and simulation contact parameters for the research and development of buckwheat sowing, threshing and hulling machinery.

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Air Blowing Into Boundary Layer Of A Flat Plate With Length-Dependent Permeability

Siberian Journal of Physics ◽

10.54362/1818-7919-2016-11-3-16-26 ◽

2016 ◽

Vol 11 (3) ◽

pp. 16-26

Author(s):

Vladimir Kornilov ◽

Andrey Boiko ◽

Ivan Kavun ◽

Anatoliy Popkov

Keyword(s):

Boundary Layer ◽

Friction Coefficient ◽

Flat Plate ◽

Skin Friction ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Skin Friction Coefficient ◽

Air Blowing ◽

The Mean

A generalized analysis of the results of numerical and experimental studies of air blowing into a turbulent boundary layer through finely perforated surface consisting of alternating permeable and impermeable sections of varying length providing a sudden change in the flow conditions at the boundaries of these sections is presented. The air blowing coefficient Cb determined by the mass flow rate per unit area of the active perforated sample varied in the range from 0 to 0.008. It is shown that as Cb grows, the maximum reduction in the mean surface skin-friction coefficient CF, which is the value through the permeable area of perforated sample, reaches about 65 %. When keeping the equal mass flow rate Q for all tested combinations, the mean skin-friction coefficient remains constant, independent of geometrical parameters of permeable and impermeable sections. Increasing the length of the last permeable section leads to the growth of relaxation region which is characterized by the reduced skin friction values on the impermeable part of the flat plate.

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Calibration and Experimental Validation of Contact Parameters for Oat Seeds for Discrete Element Method Simulations

Applied Engineering in Agriculture ◽

10.13031/aea.14381 ◽

2021 ◽

Vol 37 (4) ◽

pp. 605-614

Author(s):

Lingxin Geng ◽

Jiewen Zuo ◽

Fuyun Lu ◽

Xin Jin ◽

Chenglong Sun ◽

...

Keyword(s):

Friction Coefficient ◽

Discrete Element Method ◽

Static Friction ◽

Discrete Element ◽

Rolling Friction ◽

Angle Of Repose ◽

Static Friction Coefficient ◽

Contact Parameters ◽

Rolling Friction Coefficient ◽

Element Method

Highlights The static friction coefficient and rolling friction coefficient of oat seeds were calibrated by the discrete element method. Two representative oat varieties were selected. The hollow cylinder method and sidewall collapse method were used together to reduce the test error. Abstract . Hulless and shelled oat are two types of oat with major differences in physical appearance. To study the contact parameters between the two different oat seed types, these parameters were delineated with the discrete element method and graphic image processing technology. Using plexiglass as the contact material, the experiments used two different angle of repose measurement methods—hollow cylinder and collapse sidewall devices, to perform bench and simulation experiments on the two different oats. Under different measurement methods, bench experiments measured the angles of repose of the two oat seed types at 33.19°, 33.82° and 22.45°, 23.57°; the static friction coefficient and rolling friction coefficient were the experimental factors, and the angle of repose was the experimental indicator in the simulation. The steepest climbing experiment determined the optimal range of the experimental factor, and the regression equation between the static friction coefficient, rolling friction coefficient and angle of repose was established by a quadratic orthogonal rotation combination experiment. Finally, the angles of repose measured by the bench experiment with the two different measurement methods were treated as target values, the coefficient of static friction and the coefficient of rolling friction were solved; the coefficient of static friction between hulless oats was 0.36, and the coefficient of rolling friction between hulless oats was 0.052; the coefficient of static friction between shelled oats was 0.24, and the coefficient of rolling friction between shelled oats was 0.036. The obtained contact parameters between seeds were input into EDEM, the simulation and bench experiment results were verified. The difference between the simulation results and the actual values was within 3%. The angle of repose of oats after calibration was close to the actual situation, and the calibration results had high reliability and provided a referencefor the measurement of contact parameters between other agricultural crop seeds. Keywords: Calibration, Contact parameters, Discrete element method, Oat.

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Analysis of air jet Erosion on Duplex Stainless Steel

International Journal of Innovative Technology and Exploring Engineering - Special Issue ◽

10.35940/ijitee.b1038.1292s219 ◽

2019 ◽

Vol 9 (2S2) ◽

pp. 164-166

Keyword(s):

Stainless Steel ◽

Flow Velocity ◽

Duplex Stainless Steel ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Erosion Rate ◽

Effective Control ◽

Air Jet ◽

Impact Angles

The prevention or minimization of erosion is an urgent need. The proper selection of the material and the adopting methods for controlling the factors influencing erosion are the commonly used techniques. Duplex Stainless Steel because of its good corrosion resistance and other properties becomes a common choice. To have an effective control over erosion we must understand the effect of each parameter over the rate of erosion. Air jet test rig was used to study the erosion behavior of Duplex Stainless steel of 2205 grade in a controlled environment. Erosion tests were carried out with varying angle of impact, flow velocity and mass flow rate under standard conditions using an air jet erosion rig made according to ASTM G76 standard. Examination of the results associated with various elements such as impact angles, mass flow rate and flow velocity. The results showed that the erosion rate was maximum at lower impact angles and decreases with higher impact angles and the erosion rate increase with an increase in velocity and decrease with the increase in mass flow rate

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USING THE DISCRETE ELEMENT METHOD TO ANALYZE AND CALIBRATE A MODEL FOR THE INTERACTION BETWEEN A PLANTING DEVICE AND SOIL PARTICLES

INMATEH Agricultural Engineering ◽

10.35633/inmateh-63-42 ◽

2021 ◽

pp. 413-424

Author(s):

Fandi Zeng ◽

Xuying Li ◽

Yongzhi Zhang ◽

Zhiwei Zhao ◽

Cheng Cheng

Keyword(s):

Friction Coefficient ◽

Mass Flow ◽

Dynamic Behaviour ◽

Static Friction ◽

Discrete Element ◽

Soil Restoration ◽

Contact Interface ◽

Steel Rolling ◽

Soil Particles ◽

Static Friction Coefficient

Dynamic soil behaviour at the contact interface during transplanting makes it difficult to ensure transplanting quality. To solve this problem, the Hertz-Mindlin with bonding contact model was used to calibrate the parameters of soils in Inner Mongolia. Based on the response surface design principle, four-factor and three-level tests were performed using the repose angle as an evaluation index, and the following influence factors were considered: the soil-soil restoration coefficient, the soil-steel restoration coeficient, the soil-steel static friction coefficient and the soil-steel static friction coefficient. A regression model was analysed, and an optimization procedure yielded the following optimum combination of parameters: a soil-soil restoration coefficient of 0.45, a soil-steel restoration coefficient of 0.35, a soil-steel static friction coefficient of 0.85 and a soil-steel rolling friction coefficient of 0.13. This optimal combination was used to simulate the soil at the contact interface. The particle dynamic behaviour and soil particle mass flow were used to analyse the soil dynamic behaviour, showing that the average mass flow during the gradual opening of the duckbilled planter tends to increase over time; when the duckbilled planter gradually leaves soil, the contact interface of soil particles in the corner of the duckbilled planter unit causes a reduction in the fluctuation range of the soil mass flow, which exhibits a wave-like change. After the duckbilled planter has left soil, the contact interface of the soil changes tends to stabilize. The duckbilled planter-soil discrete element simulation model was verified. The results of this study provide a reference for the optimal design of a duckbilled planter structure.

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