Numerical Simulation of Stress-Relief Effects of Protective Layer Extraction / Symulacja numeryczna skutków odprężenia warstwy zabezpieczającej w trakcie jej wybierania

2013 ◽  
Vol 58 (2) ◽  
pp. 521-540
Author(s):  
Jia Tian-Rang ◽  
Zhang Zi-Min ◽  
Tang Chun-An ◽  
Zhang Yong-Jun
Keyword(s):  
Gas Permeability ◽  
Vertical Direction ◽  
Protective Layer ◽  
Stress Relief ◽  
Leakage Rate ◽  
Gas Leakage ◽  
Fracture Evolution ◽  
Simulation Results ◽  
Layer Extraction ◽  
Rock Strata

Field test and laboratory analog model test on the stress-relief effects of protective layer extraction are time-consuming and laborious. In this paper, on the basis of full consideration of rock heterogeinity and in combination with gas geology at Pingdingshan Mine 5, a numerical model was estalished with the gas-solid coupling rock failure process analysis system RFPA-Gas to simulate the stress variation law, roof and floor deformation, fracture evolution law, displacement in the protected seam, change in gas permeability and gas migration law during protective layer extraction. The simulation results repoduced stress variations in coal and rock strata, roof and floor deformation and fracture evolution process during protective layer extraction. The movement of rock strata were characterized by upper three zones and lower two zones: caving zone, fracture zone and bending subsidence zone in the vertical direction in the overlying strata; floor deformation and failure zone and elasto-plastic deformation zone in the vertical direction in the underlying strata. It showed that stress relief occurred in the protected seam, which led to vertical and horizontal displacements, significant increase in gas permeability, gas desorption and migration. Hence, the outburst threat in the protected seam was eliminated. Meanwhile, with comprehensive analysis of variaition of stress state, deformation characteristics and fracture distribution in coal seam and with consideration of changes in gas leakage rate, gas pressure and permeability, according to gas leakage rate, the floor strata of the protecive layer were divided into four leakage zones. They corresponded to four zones with different stress states and fracture development: original leakage zone - slow reducing leakage zone - dramatic increasing leakage zone- steady increasing leakage zone. This classification provides a clear direction for gas control in the protective layer. The simulation results are in good agreement with the stress-relief effects in field.

scholarly journals Analysis of filtration and electrical properties anisotropy of terrigenous reservoir rocks (for DDB axial zone reservoirs)

2019 ◽  
Keyword(s):  
Electrical Resistivity ◽  
Gas Permeability ◽  
Vertical Direction ◽  
Absolute Permeability ◽  
Electrical Anisotropy ◽  
Reservoir Rocks ◽  
Vertical Permeability ◽  
Irreducible Water Saturation ◽  
Horizontal Permeability ◽  
Filtration Properties

The paper focuses on the filtration and electrical anisotropy coefficients and relationship between vertical and horizontal permeability in sandstone reservoir rocks. Field case study of DDB reservoir rocks. Petrophysical properties and parameters are estimated from core and log data from a Moscovian and Serpukhovian stages of Dnipro-Donetsk Basin (West-Shebelynka area well 701-Bis and South-Kolomak area well 31). Routine core analysis included estimation of absolute permeability, open porosity, irreducible water saturation and electrical resistivity (on dry and saturated by mineralized solution) of 40 core samples along two orthogonal directions. Shale fraction is estimated using well logging data in wells which are analyzed. The authors report that reservoir rocks are represented by compacted poor-porous (φ <10 %), low permeable (k<1mD) laminated sandstone with different ratios of clay minerals (Vsh from 0,03 to 0,7) and high volume of micaceous minerals (in some cases 20-30 %). Research theory. One of the main objectives of the work is to develop empirical correlation between vertical permeability and other capacitive and filtration properties for compacted sandstone reservoirs. A modified Kozeny-Carman equation and the concept of hydraulic average radius form the basis for the technique. Results. Coefficients of the anisotropy of gas permeability (IA) and electrical resistivity (λ) are defined based on the results of petrophysical studies. The experiments proved that IA lies in a range from 0,49 to 5 and λ from 0,77 to 1,06. Permeability and electrical resistivity anisotropy in most cases have horizontal distribution. It has been shown that in West-Shebelynka area sample №1 (depth 4933 m) there is probably no fluids flow in vertical direction and in samples №№3 and 15 fractures have the vertical orientation. We have also found that the values of electrical and filtration anisotropy for all samples of South-Kolomak area are similar, this characterized the unidirectionality in their filtration properties, as well as the fact that the motion of the fluid flow mainly in the horizontal direction. In the studied rocks the degree of anisotropy has been concluded to depend on the volume of clay and micaceous minerals, their stratification, fractures, density, and their orientation. New correlation between vertical permeability, horizontal permeability and effective porosity are developed for Late Carboniferous DDB intervals that are analyzed.

Characteristics Analysis of the Automobile with Negative Stiffness Suspension

2013 ◽  
Vol 456 ◽  
pp. 189-192 ◽  
Author(s):  
Xiao Zhen Qu ◽  
Guang Quan Hou ◽  
Hao Liu ◽  
Hui He
Keyword(s):  
Natural Frequency ◽  
Ride Comfort ◽  
Vertical Direction ◽  
Negative Stiffness ◽  
Vehicle Model ◽  
Vehicle Handling ◽  
Characteristics Analysis ◽  
Vibration Transmissibility ◽  
Simulation Results

One new negative stiffness suspension is introduced in this paper. The vehicle with negative stiffness suspension has good ride comfort and handling stability. The natural frequency of system could be reduced in vertical direction by applying negative stiffness suspension. The vehicle model with negative stiffness suspension or not is built in ADAMS. The comparison of simulation results show that the vehicle with negative stiffness suspension could reduce the natural frequency of system and vibration transmissibility, and also improve the vehicle ride comfort and vehicle handling stability.

Leakage Studies With Seals for Solid-Oxide Fuel Cells

2007 ◽  
Author(s):  
Christopher K. Green ◽  
Jeffrey L. Streator ◽  
Comas Haynes ◽  
Edgar Lara-Curzio
Keyword(s):  
Fuel Cells ◽  
Solid Oxide Fuel Cells ◽  
Steel Substrate ◽  
Vertical Direction ◽  
Solid Oxide ◽  
Physical Parameters ◽  
Oxide Fuel ◽  
Element Analysis ◽  
Gas Leakage ◽  
Interfacial Gap

This research seeks to characterize the gas leakage of a mica-based compressive seal assembly in planar solid-oxide fuel cells through modeling and experiment. In particular, it is of interest to assess how certain physical parameters (i.e., seal material composition, compressive applied stress, and surface finish) affect leakage rates. Finite element analysis is used to determine the macroscopic stresses and deformations in the sealing interface, while a microscale contact mechanics analysis is employed to model the role of surface roughness on the mean interfacial gap at the interface. An averaged Reynolds equation from mixed lubrication theory is applied to model the leakage flow across the sealed interface, which is of nanometer to micrometer dimensions in the vertical direction. In conjunction with the mathematical modeling, leakage results are reported. For these tests, an annular Inconel tube was pressed against a stainless steel substrate, creating an annular sealing zone. The inside of the tube is pressurized with a test gas, the mass of which is monitored during the leakage experiment. Test results are compared to model predictions.

Development and Test of Liquefied Gas Leakage Rate Measurement Device for Limited Aperture Release

2020 ◽  
Author(s):  
Cenfan Liu ◽  
Fang Ji ◽  
Linlin Duan ◽  
Sheng Chen ◽  
Liang Sun
Keyword(s):  
Real Time ◽  
Gas Discharge ◽  
Leakage Rate ◽  
Rate Measurement ◽  
Flow Meter ◽  
Measurement Device ◽  
New Device ◽  
Gas Leakage ◽  
Before And After ◽  
Liquefied Gas

Abstract The liquefied gas has been widely used in modern chemical, energy and environment protection industries. To support the integrity management and risk assessment of liquefied gas storage tanks, it is necessary to study the leakage process of liquefied gas with limited holes. There are few researches about the liquefied gas leakage rate from the crack. At present, most measurement methods used to measure leakage rate are flow meter or weighing before and after discharge, which are not suitable for liquefied gas discharge. The discharge of liquefied gas can easily form a two-phase flow in the crack and cannot be measured by the flow meter. However, the method of weighing before and after discharge cannot measure the leakage rate in real time. To realize the leakage rate real-time, online measurement, the new liquefied gas leakage rate measurement device was set up in this study. And the detachable crack leakage modules with different diameters were designed and manufactured. Using R134a refrigerant as leakage experiment medium, the relationship between crack morphology, size, pressure and leakage rate of liquefied gas was studied on the liquefied gas leakage measurement device. The new device can be used as an experimental test platform for evaluating the consequences of different liquefied gas discharge accidents or optimizing the leakage flow coefficient of the specific leakage situation, so as to better simulate the liquefied gas discharge accidents.

Calculation of Electromagnetic Forces for EDS Type Maglev Using 3-D Finite Element Model

2021 ◽  
Author(s):  
Seonbin Lim ◽  
Junsun Yoo ◽  
No-Cheol Park
Keyword(s):  
High Speed ◽  
High Efficiency ◽  
Vertical Direction ◽  
Lateral Vibration ◽  
Maglev Train ◽  
Maglev Vehicle ◽  
Study Results ◽  
Propulsion Force ◽  
Simulation Results ◽  
Excitation Force

Abstract Electrodynamic (EDS) type suspension is appropriate for a high-speed maglev train as control is not essential to levitate a train. However, the trains might oscillate large in the vertical direction since there is no control for the EDS type maglev train. Linear Synchronous Motor (LSM) is used to propel trains as it can generate large propulsion force with high efficiency. LSM generate periodic, not uniform, Electromagnetic (EM) force and it cause vertical and lateral vibration. Therefore, EM forces acting on a maglev vehicle should be investigated to determine the vibration characteristics of a high-speed maglev train. An excitation force on bogies is nonlinearly changed by air gap between ground coils and magnets on bogies. Therefore, relative position of guide and a bogie could be defined to contracting time variant excitation force. The study focuses on verifying vertical and lateral vibration due to LSM that makes repeating propulsion force to a maglev vehicle. We made a transient 3-D EM analysis model that could simulate levitation and guidance force of a maglev vehicle. The model was constructed based on straight rail of the conventional maglev system, L0 series in Japan. We compared the simulation results, levitation, and guidance forces on single ground coil, with another study results. Also, total EM forces on a bogie in simulation results was compared with real track experimental results of another study. We could evaluate ride comport and running stability using our transient EM force by coupling with rigid body simulation.

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