Numerical Simulation of Study on Rupture Development Rules of Overburden Strata in Repeated Mining

2012 ◽  
Vol 433-440 ◽  
pp. 1933-1939 ◽  
Author(s):  
De Chao Wang ◽  
Yong Jie Yang ◽  
Kai Wang ◽  
Nan Nan Zhao
Keyword(s):  
Numerical Simulation ◽  
Development Time ◽  
Lower Layer ◽  
Thick Coal Seam ◽  
Upper Limit ◽  
Measurement Results ◽  
Mining Conditions ◽  
Final Crack ◽  
Good Agreement ◽  
Overburden Strata

Take 3 coal repeated mining of Luxi colliery as research background, overburden strata rupture development rules in repeated mining of thick coal seam were studied by using the methods of field measurement and numerical simulation. The results indicate that the height of overburden crack belt reduced along with the increase of goaf development time; the crack belt height of upper layer is 34.73m, the ratio of crack height and mining thickness is 15.1, the crack belt height of lower layer increased to 41.51m, but the increased trend declined, the ratio is only 13.84; the final crack height of numerical simulation is 39.4m, in good agreement with measurement results. The results have important guiding sense for predicting overburden rupture rules in the similar mining conditions and improving the upper limit.

Study on Overburden Strata Rupture Development Height Rules in Repeated Mining of Thick Coal Seams

2012 ◽  
Vol 170-173 ◽  
pp. 279-282
Author(s):  
Nan Nan Zhao ◽  
Yong Jie Yang ◽  
Chang Qing Wang
Keyword(s):  
Coal Seam ◽  
Field Measurement ◽  
Development Time ◽  
Lower Layer ◽  
Coal Seams ◽  
Thick Coal Seam ◽  
Upper Limit ◽  
Mining Conditions ◽  
Overburden Strata

Take 3 coal repeated mining of Luxi colliery as research background, overburden strata rupture development rules in repeated mining of thick coal seam were studied by using the methods of field measurement. The results indicate that the height of overburden crack belt reduced along with the increase of goaf development time; the crack belt height of upper layer is 34.73m, the ratio of crack height and mining thickness is 15.1, the crack belt height of lower layer increased to 41.51m, but the increased trend declined, the ratio is only 12.14, the development height after up-layer was excavated is 83.6% of the height after two coalface were excavated. The results have important guiding sense for predicting overburden rupture rules in the similar mining conditions and improving the upper limit.

The Experimental Study and Numerical Simulation of Turbulent Flow in Pumping Forebay

2009 ◽  
Author(s):  
Chao Liu ◽  
Jiren Zhou ◽  
Li Cheng
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Turbulent Flow ◽  
Three Dimensional ◽  
Computational Results ◽  
Experiment Study ◽  
Study Results ◽  
Measurement Results ◽  
Good Agreement ◽  
Made In

The experiment study was made to optimize the design of a pumping forebay. The Combined-sills were made in the forebay to eliminate the circulation and vortices of the diffusing flow successfully. The Numerical simulation of three-dimensional turbulent flow is applied on the complicate fore-and-aft flow of sills. The computational results are compared with the measurement results of physical model. The calculated results are in good agreement with the experimental data. The flow pattern is obviously improved. The study results have been applied in the project which gives a uniform approach flow to the pumping sump.

Numerical Simulation and Analysis of Rock Burst Induced by Roof Movement

2014 ◽  
Vol 522-524 ◽  
pp. 1394-1398
Author(s):  
Tao Qin ◽  
Yong Li Liu ◽  
Chang Ji Dong ◽  
Ping Wang
Keyword(s):  
Numerical Simulation ◽  
Comparative Analysis ◽  
Coal Seam ◽  
Pressure Distribution ◽  
Coal Mine ◽  
Process Simulation ◽  
Hard Coal ◽  
Thick Coal Seam ◽  
Soft Coal ◽  
Mining Conditions

For composite thick seams have been incidents burst power disasters, and seriously affect the safety of the mine production.Based on the engineering background in coal mine, through the same mining conditions, stope mining process simulation which happens in single hard coal, soft coal and single composite thick Coal Seam of Island face were studied through comparative analysis by FLAC3D　numerical simulation technology. Tendency and trend of the pressure distribution results obtain through the comparative analysis . The research results has been applied in the actual coal mining.

Modeling of mass transfer in biofilms in oscillatory flow conditions using k-ɛ turbulence model

2003 ◽  
Vol 3 (1-2) ◽  
pp. 201-207
Author(s):  
H. Nagaoka ◽  
T. Nakano ◽  
D. Akimoto
Keyword(s):  
Numerical Simulation ◽  
Mass Transfer ◽  
Turbulence Model ◽  
Uptake Rate ◽  
Oscillatory Flow ◽  
Substrate Uptake ◽  
Flow Conditions ◽  
Mass Transfer Mechanism ◽  
Substrate Uptake Rate ◽  
Good Agreement

The objective of this research is to investigate mass transfer mechanism in biofilms under oscillatory flow conditions. Numerical simulation of turbulence near a biofilm was conducted using the low Reynold’s number k-ɛ turbulence model. Substrate transfer in biofilms under oscillatory flow conditions was assumed to be carried out by turbulent diffusion caused by fluid movement and substrate concentration profile in biofilm was calculated. An experiment was carried out to measure velocity profile near a biofilm under oscillatory flow conditions and the influence of the turbulence on substrate uptake rate by the biofilm was also measured. Measured turbulence was in good agreement with the calculated one and the influence of the turbulence on the substrate uptake rate was well explained by the simulation.

Field Observation and Simulation of Sediment Resuspension in a Shallow Lake

1988 ◽  
Vol 20 (6-7) ◽  
pp. 263-270 ◽  
Author(s):  
K. Otsubo ◽  
K. Muraoka
Keyword(s):  
Numerical Simulation ◽  
Shallow Lake ◽  
Water Wave ◽  
Field Data ◽  
Sediment Resuspension ◽  
Field Research ◽  
Lake Kasumigaura ◽  
Bed Erosion ◽  
Current Water ◽  
Good Agreement

The dispersion and resuspension of sediments in Takahamairi Bay basin of Lake Kasumigaura were studied by means of field research and numerical simulation. The field data on wind direction and velocity, lake current, water wave, and turbidity were shown. Based on these results, we discuss how precipitated sediments were resuspended in this shallow lake. To predict the turbidity and the depth of bed erosion, a simulation model was established for this lake. The calculated turbidity showed good agreement with the field data. According to the simulated results, the turbidity reaches 200 ppm, and the bed is eroded several millimeters deep when the wind velocity exceeds 12 m/s in the lake.

scholarly journals A balanced-to-balanced directional coupler based on branch-slotline coupled structure

Frequenz ◽  
2020 ◽  
Vol 74 (11-12) ◽  
pp. 427-433
Author(s):  
Yaxin Liu ◽  
Feng Wei ◽  
Xiaowei Shi ◽  
Cao Zeng
Keyword(s):  
Directional Coupler ◽  
Return Loss ◽  
Design Method ◽  
Differential Mode ◽  
Arbitrary Power ◽  
Measurement Results ◽  
Transition Structures ◽  
Coupled Structures ◽  
Better Than ◽  
Good Agreement

AbstractIn this paper, a balanced-to-balanced (BTB) branch-slotline directional coupler (DC) is firstly presented, which can realize an arbitrary power division ratios (PDRs). The coupler is composed by microstrip-to-slotline (MS) transition structures and branch-slotline coupled structures. The single-ended to balanced-ended conversion is simplified and easy to implemented by the MS transition structures, which intrinsically leads to the differential-mode (DM) transmission and common-mode (CM) suppression. Moreover, the different PDRs which are controlled by the widths of branch-slotlines can be achieved. In order to verify the feasibility of the proposed design method, two prototype circuits of the proposed coupler with different PDRs are fabricated and measured. The return loss and the isolation of two designs are all better than 10 dB. Moreover, the CM suppressions are greater than 35 dB. A good agreement between the simulation and measurement results is observed.

scholarly journals Numerical Simulation of the Aerosol Particle Motion in Granular Filters with Solid and Porous Granules

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 268
Author(s):  
Olga V. Soloveva ◽  
Sergei A. Solovev ◽  
Ruzil R. Yafizov
Keyword(s):  
Numerical Simulation ◽  
Aerosol Particle ◽  
Particle Deposition ◽  
Particle Diameter ◽  
Deposition Efficiency ◽  
Hydrodynamic Resistance ◽  
Hydrodynamic Properties ◽  
Granular Filters ◽  
Limiting Value ◽  
Good Agreement

In this work, a study was carried out to compare the filtering and hydrodynamic properties of granular filters with solid spherical granules and spherical granules with modifications in the form of micropores. We used the discrete element method (DEM) to construct the geometry of the filters. Models of granular filters with spherical granules with diameters of 3, 4, and 5 mm, and with porosity values of 0.439, 0.466, and 0.477, respectively, were created. The results of the numerical simulation are in good agreement with the experimental data of other authors. We created models of granular filters containing micropores with different porosity values (0.158–0.366) in order to study the micropores’ effect on the aerosol motion. The study showed that micropores contribute to a decrease in hydrodynamic resistance and an increase in particle deposition efficiency. There is also a maximum limiting value of the granule microporosity for a given aerosol particle diameter when a further increase in microporosity leads to a decrease in the deposition efficiency.

Modeling of Discrete Tip Injection in a Two-Dimensional Streamline Curvature Method

2012 ◽  
Author(s):  
Roland Matzgeller ◽  
Richard Pichler
Keyword(s):  
Rotating Stall ◽  
Streamline Curvature ◽  
Measurement Results ◽  
Compressor Design ◽  
Multistage Compressor ◽  
Physical Effects ◽  
Tip Injection ◽  
Stability Enhancement ◽  
Good Agreement ◽  
Streamline Curvature Method

Fluid injection at the tip of highly loaded compressor rotors is known to be effective in suppressing the onset of rotating stall and eventually compressor instability. However, using such stability enhancement methods in a multistage compressor might not only stabilize certain stages but has also an impact on radial and axial matching. In order to account for tip injection during the early stages of compressor design, this paper focuses on the development of a method to model the physical effects underlying tip injection within a streamline curvature method. With the help of system identification it could be shown that a rotor subject to the discrete jets of tip injection adapts to the varying flow conditions according to a first order model. This information was used to generate a time-dependent input for the steady equations used with a streamline curvature method and eventually to model the unsteady response of the rotor to tip injection. Comparing the results obtained with the enhanced streamline curvature model to measurement results, good agreement could be shown which raised confidence that the influence of tip injection on axial and radial matching was sufficiently captured.

Turbulent dispersion in a non-homogeneous field

1999 ◽  
Vol 392 ◽  
pp. 45-71 ◽  
Author(s):  
ILIAS ILIOPOULOS ◽  
THOMAS J. HANRATTY
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Stochastic Model ◽  
Point Source ◽  
Time Scales ◽  
Langevin Equation ◽  
Turbulent Dispersion ◽  
Homogeneous Field ◽  
Fully Developed Flow ◽  
Good Agreement

Dispersion of fluid particles in non-homogeneous turbulence was studied for fully developed flow in a channel. A point source at a distance of 40 wall units from the wall is considered. Data obtained by carrying out experiments in a direct numerical simulation (DNS) are used to test a stochastic model which utilized a modified Langevin equation. All of the parameters, with the exception of the time scales, are obtained from Eulerian statistics. Good agreement is obtained by making simple assumptions about the spatial variation of the time scales.

Numerical Simulation of Ring-Shape Rock Failure under Compressive Loading

2011 ◽  
Vol 378-379 ◽  
pp. 15-18
Author(s):  
Yong Bin Zhang ◽  
Zheng Zhao Liang ◽  
Shi Bin Tang ◽  
Jing Hui Jia
Keyword(s):  
Numerical Simulation ◽  
Fracture Process ◽  
Failure Modes ◽  
Failure Process ◽  
Compressive Loading ◽  
Orientation Angle ◽  
Crack Orientation ◽  
Ring Specimen ◽  
Ring Shape ◽  
Good Agreement

In this paper, a ring shaped numerical specimen is used to studying the failure process in brittle materials. The ring specimen is subjected to a compressive diametral load and contains two angled central cracks. Numerical modeling in this study is performed. It is shown that the obtained numerical results are in a very good agreement with the experiments. Effect of the crack orientation angle on the failure modes and loading-displace responses is discussed. In the range of 0°~40°, the fracture paths are curvilinear forms starting from the tip of pre-existing cracks and grow towards the loading points. For the crack orientation angle 90°, vertical fractures will split the specimen and the horizontal cracks do not influence the fracture process.

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