Mass-front velocity of dry granular flows influenced by the angle of the slope to the runout plane and particle size gradation

2016 ◽  
Vol 13 (2) ◽  
pp. 234-245 ◽  
Author(s):  
Xiao-yi Fan ◽  
Shu-jun Tian ◽  
You-yi Zhang
Keyword(s):  
Particle Size ◽  
Granular Flows ◽  
Front Velocity ◽  
Particle Size Gradation

scholarly journals Experimental Study on Nonlinear Seepage Characteristics and Particle Size Gradation Effect of Fractured Sandstones

2018 ◽  
Vol 2018 ◽  
pp. 1-11
Author(s):  
Xuyang Shi ◽  
Wei Zhou ◽  
Qingxiang Cai ◽  
Xiang Lu
Keyword(s):  
Particle Size ◽  
Fractal Dimension ◽  
Fractured Rock ◽  
Average Pore Size ◽  
Fractured Rock Mass ◽  
Average Pore ◽  
Seepage Pressure ◽  
Seepage Characteristics ◽  
Fractured Sandstone ◽  
Particle Size Gradation

Seepage mutation of fractured rock mass is one of the main inducements of dump slide and other disasters. Pore structure is a significant factor affecting the seepage characteristics of fractured rock mass, while particle size gradation has an important effect on the distribution of pore structure. Through the self-developed experimental system, the nonlinear seepage test on the fractured sandstones of the coalseam roof was conducted to investigate the influence of seepage pressure, porosity, and fractal dimension. Besides, the nonlinear seepage model was established by Barree–Conway theory. The results showed that, during the seepage process of fractured sandstone, there were significant nonlinear characteristics, which increased with the increase of the seepage pressure. With the increasing porosity, there was greater average pore size of fractured sandstone, stronger permeability, and weaker nonlinear seepage. The seepage characteristics approximated to that of Darcy model. However, with increasing grading fractal dimension, there were smaller average pore size of fractured sandstone, weaker permeability, and stronger nonlinear seepage. The seepage characteristics approximated to that of Forchheimer model.

Microstructure Modification of NiO/YSZ Anode in Solid Oxide Fuel Cell by Particle Size Gradation of YSZ

2012 ◽  
Vol 519 ◽  
pp. 32-35
Author(s):  
Qi Bing Chang ◽  
Xia Wang ◽  
Jian Er Zhou ◽  
Yong Qing Wang ◽  
Guang Yao Meng ◽  
...  
Keyword(s):  
Particle Size ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Bending Strength ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Mass Ratio ◽  
Obvious Effect ◽  
Microstructure Modification ◽  
Particle Size Gradation

The idealized microstructure of NiO/YSZ anode of solid oxide fuel cell (SOFC) is that YSZ structures the bone of the anode and NiO is segregated by YSZ to keep Ni from congregation. To obtain this microstructure, the mixture of coarse YSZ and fine YSZ was used. The effect of the particle size gradation of YSZ on the microstructure of anode was studied. The results show that the homogenous microstructure can be obtained when the mass ratio of the coarse YSZ (d50＝3.38µm) to the fine YSZ (d50＝0.4µm) is 7:3. The pre-sintering temperature has obvious effect on the porosity of the NiO/YSZ. The bending strength of NiO/YSZ and Ni/YSZ are 123MPa and 85MPa, respectively. The reduction of NiO to Ni has less effect on the bending strength for 40vol%Ni/YSZ (7/3).

scholarly journals Effect of fractal particle size distribution on the mobility of dry granular flows

AIP Advances ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 095113
Author(s):  
Zhiqiang Lai ◽  
Dong Chen ◽  
Enhui Jiang ◽  
Lianjun Zhao ◽  
Luis E. Vallejo ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Granular Flows ◽  
Fractal Particle

Effect of AlF3 Addition on Electric Conductivity of NiFe2O4-Based Cermet Inert Anode

2014 ◽  
Vol 881-883 ◽  
pp. 1391-1395
Author(s):  
Fu Xiang Wei ◽  
Gen Xi Yu ◽  
Zhi Ling Wang
Keyword(s):  
Particle Size ◽  
Electric Conductivity ◽  
Inert Anode ◽  
Metallic Phase ◽  
Ceramic Phase ◽  
Ceramic Particles ◽  
Pure Sample ◽  
The Impact ◽  
Particle Size Gradation ◽  
Better Than

In this study, a combination of a two-step sintering and a particle size gradation technique was used to prepare cermet samples. We focused on the impact of the AlF3 additive on the performance of the cermet. We found that the addition of AlF3 doesnt significantly improve the density and porosity of Ag-NiFe2O4, since the addition of the AlF3 did not reduce the particle size, nor did it promote the tight packing of NiFe2O4 in a spinel-based cermet. However, we did observe a significant enhancement in its conductivity. The sample with 3% additive has the highest conductivity at 22.53S·cm-1 at 900°C, nearly 3.8 times better than the pure sample. An Analysis of the cermet microstructure showed that adding AlF3 can improve wetting between the ceramic phase and the silver metallic phase. It also facilitates the distribution of silver along the contour of the ceramic particles, which contributes to the improved conductivity of the nickel-based cermet.

Some factors affecting mass-front velocity of rapid dry granular flows in a large flume

2011 ◽  
Vol 122 (3-4) ◽  
pp. 249-260 ◽  
Author(s):  
Qingqing Yang ◽  
Fei Cai ◽  
Keizo Ugai ◽  
Masao Yamada ◽  
Zhiman Su ◽  
...  
Keyword(s):  
Granular Flows ◽  
Front Velocity ◽  
Factors Affecting

scholarly journals Experimental Investigation on the Impact Dynamics of Saturated Granular Flows on Rigid Barriers

2021 ◽  
Vol 27 (1) ◽  
pp. 127-138
Author(s):  
Nicoletta Sanvitale ◽  
Elisabeth Bowman ◽  
Miguel Angel Cabrera
Keyword(s):  
Particle Size ◽  
High Speed ◽  
Impact Load ◽  
Granular Flows ◽  
Normal Pressure ◽  
Impact Behavior ◽  
Small Scale ◽  
Rigid Barrier ◽  
Fluid Saturation ◽  
The Impact

ABSTRACT Debris flows involve the high-speed downslope motion of rocks, soil, and water. Their high flow velocity and high potential for impact loading make them one of the most hazardous types of gravitational mass flows. This study focused on the roles of particle size grading and degree of fluid saturation on impact behavior of fluid-saturated granular flows on a model rigid barrier in a small-scale flume. The use of a transparent debris-flow model and plane laser-induced fluorescence allowed the motion of particles and fluid within the medium to be examined and tracked using image processing. In this study, experiments were conducted on flows consisting of two uniform and one well-graded particle size gradings at three different fluid contents. The evolution of the velocity profiles, impact load, bed normal pressure, and fluid pore pressure for the different flows were measured and analyzed in order to gain a quantitative comparison of their behavior before, during, and after impact.

scholarly journals Numerical Simulation of Granular Column Collapse with Fractal Particle Size Distribution Using Discrete Element Method

2021 ◽  
Vol 2068 (1) ◽  
pp. 012009
Author(s):  
Zhiqiang Lai ◽  
Li Pan ◽  
Zhongmei Wang ◽  
Jiayi Wang ◽  
Yanfen Ren
Keyword(s):  
Particle Size ◽  
Fractal Dimension ◽  
Kinetic Energy ◽  
Discrete Element Method ◽  
Granular Flows ◽  
Discrete Element ◽  
Column Collapse ◽  
Particle Kinetic Energy ◽  
Granular Column ◽  
Fractal Particle

Abstract This study conducts numerical simulations of the granular column collapse with Fractal Particle Size Distributions (FPSDs) via the Discrete Element Method (DEM) and investigated kinetic behaviours of dry granular flows. The aim of this paper is to explore the effects of the fractal dimension of FPSD on the kinetics of dry granular flows. When the fractal dimension of the flows consisting of granular materials increases, the horizontal particle translational velocities become greater and the mobility improves, whereas the particle rotational velocities decrease. Meanwhile, the change in the potential energy increases, and the particle kinetic energy in the rotational form reduces; thus, the particle kinetic energy in the translational form increases. The reducing particle rotational movement may be related to the reducing particle shearing behaviours because only the contact shearing can affect particle rotational motion. In conclusion, a larger fractal dimension of FPSD of a dry granular flow leads to a longer spreading distance and a smaller rotational velocity.

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