Flow behavior of granular material during funnel and mixed flow discharges: A comparative analysis

Author(s):  
Dancheng Zhang ◽  
Shijie Dong ◽  
Hui Guo ◽  
Xiaodong Yang ◽  
Lijie Cui ◽  
...  
2022 ◽  
Vol 10 (1) ◽  
pp. 27-44
Author(s):  
D. M Priyantha Wedagama ◽  
I Wayan Suweda ◽  
N. L. G Astariyani

2021 ◽  
Author(s):  
Laurie Jayne Kurilla ◽  
Giandomenico Fubelli

Abstract Debris flows, and landslides in general, are worldwide catastrophic phenomena. As world population and urbanization grow in magnitude and geographic coverage, the need exists to extend focus, research, and modeling to a continental and global scale.Although debris flow behavior and parameters are local phenomena, sound generalizations can be applied to debris flow susceptibility analyses at larger geographic extents based on these criteria. The focus of this research is to develop a global debris flow susceptibility map by modeling at both a continental scale for all continents and by a single global model and determine whether a global model adequately represents each continent. Probability Density, Conditional Probability, Certainty Factor, Frequency Ratio, and Maximum Entropy statistical models were developed and evaluated for best model performance using fourteen environmental factors generally accepted as the most appropriate debris flow predisposing factors. Global models and models for each continent were then developed and evaluated against verification data. The comparative analysis demonstrates that a single global model performs comparably or better than individual continental models for a majority of the continents, resulting in a debris flow susceptibility map of the world useful in international planning, and future debris flow susceptibility modeling for determining societal impacts.


Author(s):  
Monica MIRONESCU ◽  
Ion Dan MIRONESCU ◽  
Maria Iasmina MOZA ◽  
Adrian TRIFAN ◽  
Vionela MIRONESCU

Starch hydrolysates production converts starch to different kinds of products using enzymes in two steps, liquefaction and saccharification. This study investigated three types of analysis methods for the assessing and characterization of the liquefaction process: a rheological method (to measure yield stress), a chemical method (for the determination of Dextrose Equivalent DE) and a chromatographic method (HPLC to obtain the Degrees of Polymerization DPs).  Potato starch with 13.5% dry substance was liquefied with the enzyme Liquozyme Supra for two hours in optimal conditions of pH and temperature. A comparative analysis between the methods to describe the liquefaction process was realised. Yield stress offered valuable information on the flow behavior of the samples showing that after 15 minutes of liquefaction the product behaves as a fluid without yield point, with a decreasing value of the middle yield stress. DE had an ascending value during liquefaction indicating that the total reducing sugars are increasing in time. After two hours of liquefaction, glucose (DP1) in very small amounts (around 1%), maltotriose (DP3) and maltotetrose (DP4) in much higher amounts were obtained; no maltose was produced. The quantity of DP3 and DP4 was increasing with the liquefaction time whereas the content in oligosaccharides with DP 5 or higher as 5 (DP5+) was decreasing. The comparative analysis of the chemical and the chromatographic method showed that both methods characterize very well the liquefaction process. It was found that there was a strong relationship between the DE values and the total DP3+DP4 as measured from HPLC and also between DE and DP5+. 


Author(s):  
Shinji Honami ◽  
Keizo Tsukagoshi ◽  
Toshimichi Sakai ◽  
Ichiro Watanabe

Velocity profile measurements were performed on the flow in a mixed-flow diffuser with walls having equal cone angles. The aim of the present study is to understand the flow behavior and the relation between the flow patterns and the diffuser losses. The boundary layer flow accompanied by separation on the inner wall and the velocity normal to the diffuser walls were measured in detail to examine the three-dimensional flow behavior in the mixed-flow diffuser. Comparing with the radial diffuser, the mixed-flow diffuser had a more complicated flow mechanism as it had the pressure gradients of transverse and normal directions.


2002 ◽  
Vol 13 (2) ◽  
pp. 167-180 ◽  
Author(s):  
Shu-San Hsiau ◽  
Ming-Yuan Ou ◽  
Chi-Hwang Tai

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1937
Author(s):  
Bin Yang ◽  
Hong Lei ◽  
Yingshi Xu ◽  
Kun Liu ◽  
Peng Han

In the continuous process, fluid flow is an important physical phenomena in the tundish, as it affects the process of heat transfer, bubble motion and inclusion collision-coalescence and grow up. This paper undertakes a detailed numerical investigation of fluid flow characteristics in the tundish with and without induction heating. The individual unit method and the volume subtraction model are applied to analyze the flow characteristics. A quantitative evaluation method of flow characteristics is proposed to investigate the flow characteristics. In the tundish with and without induction heating, firstly, the main flow behavior of molten steel is mixed flow in the receiving chamber; secondly, the main flow behavior of molten steel is plug flow in the channel; lastly, the main flow pattern is mixed flow, and the minor flow pattern is plug flow in the discharging chamber. The method of the volume subtraction model is an effective way to analyze the flow characteristics in the tundish with channel induction heating.


2017 ◽  
Vol 22 (2) ◽  
pp. 49-56
Author(s):  
Selam Waktola ◽  
Andre Bieberle ◽  
Frank Barthel ◽  
Martina Bieberle ◽  
Uwe Hampel ◽  
...  

Abstract This paper presents an application of an ultrafast electron beam X-ray CT scanner for investigating the gravitational flow behavior of granulates through cylindrical silo model. The CT scanner allows obtaining crosssectional images of the granular material distribution with a spatial resolution of approximately 1 mm and a time resolution of 2 kHz. In order to conduct a deep analysis of the granular flow concentration changes, two image processing algorithm steps were applied. The first step deals with preprocessing and re-centering stacks of raw images. The second step divides the preprocessed image into several concentric rings and calculates the mean value to study radial concentration changes. Independent analysis of granular concentration in each ring provides useful knowledge to study the silo discharging during mass flow and funnel flow.


Author(s):  
Shinpei Mizuki ◽  
Toshimichi Sakai ◽  
Ichiro Watanabe

An Investigation of the flow patterns within the centrifugal and mixed-flow impeller channel were performed. The velocity distributions within the impeller channel and blade surface pressure of the centrifugal and mixed-flow impellers were closely examined by experiment and the flow behavior within these impellers were clarified. The incompressible and inviscid flow within the impellers having straight radial blades were also derived analytically. The present authors assumed an outermost boundary of the relative eddy at the impeller exit periphery and corrected the analytical results. The corrected analytical results thus obtained showed good coincidence with the experimental data.


Author(s):  
Andreas Svanberg ◽  
Simon Larsson ◽  
Rikard Mäki ◽  
Pär Jonsén

Abstract Rope shovels and other heavy mining equipment used for loading fragmented rocks to extract minerals from the earth are used in almost every open pit mine. The optimization of the loading process is of enormous value due to the extremely large amount of material turn over. In this work, a full-scale numerical model of the loading process is developed. Granular material of copper ore is modeled in a combination of rigid finite elements for larger particles with complex shapes, and the discrete element method for smaller particles. A multi rigid body dynamic model, discretized with finite elements are used to model the rope shovel. Calibration of the numerical model for the granular material is performed via a new and unique experimental full-scale approach of analyzing waste rock pile angles with a height of approximately 15 m. In situ experimental data acquisition is performed during the loading process for validation of the model. After model validation, the influence of several loading variables such as bucket rake angle, velocity, and position from the pile are investigated and evaluated. When comparing the numerical model results with experimental mass measurement an excellent agreement was observed. Also, drone camera video recordings of the mass flow behavior and the numerical mass flow behavior are in agreement. Small adjustments of dig variables show a significant effect on the average dig force as well as the bucket fill factor.


2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Sahand Pirouzpanah ◽  
Abhay Patil ◽  
Yiming Chen ◽  
Gerald Morrison

Electrical submersible pumps (ESPs) are widely used in upstream oil production. The presence of a low concentration solid phase, particle-laden flow, in the production fluid may cause severe damage in the internal sections of the pump which reduces its operating lifetime. To better understand the ESP pump's endurance, two different designs of commonly used mixed flow ESPs were studied numerically to determine the pump's flow behavior at its best efficiency point. Computational fluid dynamics (CFD) analysis was conducted on two stages of one design type of pump's primary flow path employing Eulerian–Granular scheme in ANSYS FLUENT. The key parameters affecting the erosion phenomena within the pump such as turbulence kinetic energy, local sand concentration, and near wall relative sand velocity were identified. The predictive erosion model applicable to pumps was developed by correlating the erosion key parameters with available experimental results. It is concluded that the use of an erosion model on the second design of ESP proves the model's versatility to predict the erosion on different designs of ESPs.


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