scholarly journals Axial Blast Type Discharge Chamber with Moving Electrode

2019 ◽  
Vol 6 (3) ◽  
pp. 227-230
Author(s):  
M. E. Pinchuk ◽  
A. V. Budin ◽  
N. K. Kurakina ◽  
A. G. Leks
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Gas Dynamics ◽  
Gas Flow ◽  
Discharge Chamber ◽  
Gas Pressure ◽  
Current Amplitude ◽  
Experimental Stand ◽  
Design Changes ◽  
Gas Pressures

The paper presents some results concerning electrophysical and gas-dynamics parameters of high-curent arc in axial blast discharge chamber. The experimental stand and numerical model were modified for axial gas flow type. Some design changes are described in the paper. The experiments were carried out for gas pressures of 1.0-6.0 MPa with current amplitude of 25-150 kA. The current half-period was of 1.0-10.0 ms. The contacts moved apart to the distance of 3-4 cm due to gas pressure boost in the chamber. OpenFOAM package with the library swak4foam was used for numerical simulation.

Pressure Assisted Sintering of an Aluminium Alloy

2009 ◽  
Vol 618-619 ◽  
pp. 627-630
Author(s):  
Stephen J. Bonner ◽  
Graham B. Schaffer ◽  
Ji Yong Yao
Keyword(s):  
Aluminium Alloy ◽  
Gas Flow ◽  
Isothermal Holding ◽  
Horizontal Tube ◽  
Elevated Pressure ◽  
Nitrogen Pressure ◽  
Gas Pressure ◽  
Densification Rate ◽  
Conventional Press ◽  
Gas Pressures

An aluminium alloy was sintered using a conventional press and sinter process, at various gas pressures, to observe the effect of sintering gas pressure on the densification rate. Compacts of aluminium alloy 2712 (Al-3.8Cu-1Mg-0.7Si-0.1Sn) were prepared from elemental powders and sintered in a horizontal tube furnace under nitrogen or argon at 590°C for up to 60 minutes, and air cooled. The gas flow was adjusted to achieve specific gas pressures in the furnace. It has been found that increasing the nitrogen pressure at the start of the isothermal holding stage to 160kPa increased the densification rate compared to standard atmospheric pressure sintering. Increasing the nitrogen pressure further, up to 600kPa, had no additional benefit. The densification rate was increased significantly by increasing the gas pressure to 600kPa during both heating and isothermal holding. Under argon the elevated pressure did not increase the densification rate. Results seem to suggest that the beneficial effect of the elevated pressure on the rate of densification is related to nitride formation.

GROWTH OF NANOPHASE PARTICLES IN FREE-MOLECULAR REGIME AND ITS DEPENDENCE ON MEDIUM-GAS PRESSURE

1996 ◽  
Vol 03 (01) ◽  
pp. 45-47
Author(s):  
S. AONO ◽  
M. ITOH ◽  
H. TAKANO ◽  
S. TOHNO
Keyword(s):  
Numerical Simulation ◽  
Monte Carlo ◽  
Monte Carlo Method ◽  
Linear Relation ◽  
Gas Flow ◽  
Gas Pressure ◽  
Cold Trap ◽  
Simple Relationship ◽  
Free Molecule ◽  
Free Molecular Regime

A clear linear relation between the gas pressure and the diameter of nanophase particles generated from the modified gas-flow/cold-trap method was obtained for several kinds of metallic nanophase particles. This simple relationship was also verified by numerical simulation using a Monte-Carlo method on the diffusion and coagulation of clusters in a free-molecule regime.

Water and Gas Movement in Mx80 Bentonite Buffer Clay

2003 ◽  
Vol 807 ◽  
Author(s):  
Stephen T. Horseman ◽  
Jon F. Harrington ◽  
P. Sellin
Keyword(s):  
Boundary Conditions ◽  
Capillary Pressure ◽  
Gas Flow ◽  
Water Saturation ◽  
Swelling Pressure ◽  
Gas Pressure ◽  
Constant Volume ◽  
Total Stress ◽  
Porewater Pressure ◽  
Gas Pressures

ABSTRACTThis paper describes a long-term laboratory test designed to examine the sensitivity of gas flow in Mx80 buffer bentonite subject to a constant volume boundary condition. A constant volume and radial flow (CVRF) apparatus was designed to enable gas flow from a centrally located injection filter to be independently monitored at three sink-filter arrays mounted around the circumference of the clay specimen. Axial and radial total stresses and internal porewater pressure were continuously monitored. Gas entry, breakthrough and peak gas pressures were found to be systematically higher under constant volume boundary conditions than under previously reported constant stress and radially-constrained test conditions [6, 9, 10]. The observation that gas pressures are sensitive to test boundary conditions supports the hypothesis that gas entry is accompanied by dilation of the bentonite fabric. Gas penetration of the clay caused a substantial increase in total stress and internal porewater pressure. Abrupt drops in gas pressure, accompanied by similar drops in total stress, were interpreted as fracture propagation events. The outflow of gas was always non-uniformly distributed between the sinks. Furthermore, the distribution of flow between sinks often changed abruptly during the course of an experiment indicating that gas pathways were very unstable. When gas injection stopped, the gas pressure and rate of outflow spontaneously declined with time. Under constant volume conditions, the gas pressure at the asymptote exceeded the internal porewater pressure by an amount equal to the capillary pressure. In constant volume tests on clay with high water saturation, capillary pressure has a value close to the measured swelling pressure of the clay.

Numerical Simulation of Gas-Solid Coupling in Coal Face

2010 ◽  
Vol 29-32 ◽  
pp. 1791-1796
Author(s):  
Liang Bing ◽  
Li Ye
Keyword(s):  
Numerical Simulation ◽  
Gas Flow ◽  
Coupling Effect ◽  
Gas Pressure ◽  
Coal Face ◽  
Gas Emission ◽  
Plastic Failure ◽  
Safety Production ◽  
External Loads

Gas accidents in coal face threaten the safety production. Studying on gas emission law could help us avoid. The gas-solid coupling models with different mining styles were built up. Simulation of stress-displacement-gas coupling was made by Flac3D, combining with the background of Lu Ning coal. Results shows: the longer blasting time is, the larger plastic failure zones are; with the same external loads, strains of coal are larger when considering gas-solid coupling effect, gas flow to the coal face easily. Gas pressure turns to be nonlinear along tunneling direction used blasting, the longer blasting time is, the smaller gas pressure is. The gas pressure turns to be linear 0~10m to coal face with mechanical. The greatest variation of displacement and gas pressure are 0~3m to coal face, gas emission mainly occurred here.

scholarly journals Analyzing Influence of Ignition Gas Flow Pipe of Igniter on Working Process

2018 ◽  
Vol 36 (6) ◽  
pp. 1193-1201
Author(s):  
Jiang Chang ◽  
Gongping Wu ◽  
Haodong Wu ◽  
Xuejie Hao
Keyword(s):  
Numerical Simulation ◽  
Combustion Chamber ◽  
Atmospheric Pressure ◽  
Gas Dynamics ◽  
Gas Flow ◽  
Chamber Pressure ◽  
Steady State Flow ◽  
Working Process ◽  
Working Performance ◽  
Velocity Pressure

Based on gas dynamics and computational fluid dynamics, the numerical simulation of the steady-state flow field of igniter working in the two conditions was conducted with FLUENT. The numerical simulation results were validated by experiments. Influences of ignition gas flow pipe on the igniter's working performance were analyzed on the basis of test validation. The analysis results show that the combustion chamber pressure has atmospheric pressure and that the igniter works with ignition gas flow pipe. The velocity of throat is lower than the speed of sound and the sonic position moves to the position of ignition gas flow pipe; the velocity, pressure and temperature of throat increase; but the flux, pressure and temperature of outlet decrease. Under the different conditions of combustion chamber pressure, the outlet velocity, pressure, temperature and flux have a stable section; but the flux decreases.

scholarly journals Engine Speed and Load on the Sealing Capacity of a Piston Ring-Pack

2020 ◽  
Vol 5 (3) ◽  
pp. 304-313
Author(s):  
Erjon Selmani ◽  
Arian Bisha
Keyword(s):  
Gas Dynamics ◽  
Gas Flow ◽  
Piston Ring ◽  
Engine Speed ◽  
Fuel Mixture ◽  
Sealing Capacity ◽  
Piston Ring Pack ◽  
Ring Pack ◽  
Two Parameters ◽  
Gas Pressures

The combustion chamber is ought to be perfectly sealed, however, part of the air and fuel mixture can escape from it. Among the several losses there is the gas flow from the inter-ring crevices, which is always present. This leakage is known as blow-by, and affects efficiency, correct lubrication and emissions. The amount of leakage is dependent on many factors, and among the most important are the engine speed and load, which are able to affect the system through the forces applied on it. The aim of this paper was to understand in a more detailed way how the engine speed and load could affect the sealing efficiency of a ring-pack. For this purpose, a complete range of speeds and loads were used in the simulations. The equations of the ring motions and gas dynamics has been implemented and solved in ©Ricardo RINGPAK solver. The results showed that inertia and inter-ring gas pressures drives the sealing behavior of the rings. The blow-by trend showed to decrease with the speed and increase with the load, exception made for the idle condition where the values were different to the other cases, especially at higher speeds. Among the two parameters, the engine speed resulted to affect more significantly the blow-by trend.

Numerical Simulation on the Influence of Mining-Induced Fractures Field on Gas Drainage and its Application

2011 ◽  
Vol 90-93 ◽  
pp. 477-484
Author(s):  
Shu Jing Zhang ◽  
Yong Wei Peng ◽  
Yong Jiang Yu
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Gas Flow ◽  
Underground Mining ◽  
High Strength ◽  
Gas Pressure ◽  
Comsol Multiphysics ◽  
Coal Seam Gas ◽  
Gas Drainage ◽  
Induced Fractures

In order to study the influence of mining-induced fractures field on gas drainage,the paper adopts software of numerical simulation COMSOL Multiphysics to simulate gas drainage of coal seam under the condition of high-strength underground mining. The main aspects can be seen as the following: (1) In the case without considering the fractures, gas drainage in single hole, the gas pressure distribution showed a funnel-type distribution in space along the drainage holes around. (2) The orientation and direction of fractures play a major role on the flow field of gas. In the region that exits fractures, the distribution of gas pressure has a clear fluctuation and adjustment.(3) The numerical simulation of coal seam gas drainage that considered the fracture of coal mining, was closer to the true gas flow.

scholarly journals Blowing and drifting snow in Alpine terrain: numerical simulation and related field measurements

1998 ◽  
Vol 26 ◽  
pp. 174-178 ◽  
Author(s):  
Peter Gauer
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Three Dimensional ◽  
Field Measurements ◽  
Blowing Snow ◽  
Related Field ◽  
Drifting Snow ◽  
Physically Based ◽  
Snow Transport

A physically based numerical model of drifting and blowing snow in three-dimensional terrain is developed. The model includes snow transport by saltation and suspension. As an example, a numerical simulation for an Alpine ridge is presented and compared with field measurements.

scholarly journals Thermochemical Heat Storage in a Lab-Scale Indirectly Operated CaO/Ca(OH)2 Reactor—Numerical Modeling and Model Validation through Inverse Parameter Estimation

2021 ◽  
Vol 11 (2) ◽  
pp. 682
Author(s):  
Gabriele Seitz ◽  
Farid Mohammadi ◽  
Holger Class
Keyword(s):  
Numerical Model ◽  
Gas Flow ◽  
Reaction Rate ◽  
Heat Storage ◽  
Bulk Material ◽  
Fixed Bed ◽  
Experimental Results ◽  
Fixed Bed Reactor ◽  
Thermochemical Heat Storage ◽  
Speed Up

Calcium oxide/Calcium hydroxide can be utilized as a reaction system for thermochemical heat storage. It features a high storage capacity, is cheap, and does not involve major environmental concerns. Operationally, different fixed-bed reactor concepts can be distinguished; direct reactor are characterized by gas flow through the reactive bulk material, while in indirect reactors, the heat-carrying gas flow is separated from the bulk material. This study puts a focus on the indirectly operated fixed-bed reactor setup. The fluxes of the reaction fluid and the heat-carrying flow are decoupled in order to overcome limitations due to heat conduction in the reactive bulk material. The fixed bed represents a porous medium where Darcy-type flow conditions can be assumed. Here, a numerical model for such a reactor concept is presented, which has been implemented in the software DuMux. An attempt to calibrate and validate it with experimental results from the literature is discussed in detail. This allows for the identification of a deficient insulation of the experimental setup. Accordingly, heat-loss mechanisms are included in the model. However, it can be shown that heat losses alone are not sufficient to explain the experimental results. It is evident that another effect plays a role here. Using Bayesian inference, this effect is identified as the reaction rate decreasing with progressing conversion of reactive material. The calibrated model reveals that more heat is lost over the reactor surface than transported in the heat transfer channel, which causes a considerable speed-up of the discharge reaction. An observed deceleration of the reaction rate at progressed conversion is attributed to the presence of agglomerates of the bulk material in the fixed bed. This retardation is represented phenomenologically by mofifying the reaction kinetics. After the calibration, the model is validated with a second set of experimental results. To speed up the calculations for the calibration, the numerical model is replaced by a surrogate model based on Polynomial Chaos Expansion and Principal Component Analysis.

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