The Numerical Simulation Research on Thermal Flow-Reversal Reactor of Mine Ventilation Gas

2014 ◽  
Vol 926-930 ◽  
pp. 1627-1631
Author(s):  
Wei Feng Zou ◽  
Bo Lan
Keyword(s):  
Numerical Simulation ◽  
Gas Flow ◽  
Single Channel ◽  
Volume Fraction ◽  
Mine Ventilation ◽  
Optimal Operation ◽  
Flow Reversal ◽  
Thermal Flow ◽  
Reactor Performance ◽  
Operation Condition

The paper uses computational fluid dynamics software FLUENT to build a single-channel numerical simulation model of the mine ventilation gas Thermal Flow-Reversal Reactor (TFRR). Combining with the analysis of orthogonal test, the influences that four factors (Initial temperature distribution, Ventilation gas flow velocity, Volume fraction of methane, Exchange period) act on reactor performance is investigated. An optimal operation condition is proposed by the establishment of the priority sequence of these four factors.

Study on the Mixer Used for the Thermal Flow-Reversal Reactor

2011 ◽  
Vol 201-203 ◽  
pp. 2451-2455
Author(s):  
Yong Qi Liu ◽  
Xiang Chun Chen ◽  
Rui Xiang Liu ◽  
Zhen Qiang Gao ◽  
Jing Tao Wang
Keyword(s):  
Structural Parameters ◽  
Mine Ventilation ◽  
Hole Diameter ◽  
Flow Reversal ◽  
Thermal Flow ◽  
Mixing Process ◽  
Mixing Effect ◽  
Coal Mine Methane ◽  
Methane Drainage ◽  
Calculation Results

Large amount of methane is emitted into the atmosphere by mine ventilation and methane drainage systems each year. In this paper, a mixer is developed, which can mix drained coal mine methane with ventilation air methane to be oxidized together in the thermal flow-reversal reactor. The mixing process and the effects of the structural parameters of the mixer on the mixing effect are numerical investigated. The calculation results indicate that reducing the maximum injector diameter will lead to worse uniformity of the mixture. While the uniformity can be improved with increasing the injector angle from 30 to 45 degree, and the improvement is more obvious by reducing the injecting hole diameter under the sum area of the injecting holes fixed. This work is helpful to improve the design of the mixer.

Numerical Simulation of Particle-Gas Flow Through a Fixed Pipe, Using One-Way and Two-Way Coupling Methods

2016 ◽  
Vol 33 (2) ◽  
pp. 205-212 ◽  
Author(s):  
Z. Namazian ◽  
A. F. Najafi ◽  
S. M. Mousavian
Keyword(s):  
Numerical Simulation ◽  
Gas Flow ◽  
Volume Fraction ◽  
Fluid Velocity ◽  
Particle Volume Fraction ◽  
Stokes Number ◽  
Continuous Phase ◽  
Turbulent Pipe Flow ◽  
Particle Volume ◽  
Two Phase

AbstractA numerical simulation of the particle-gas flow in a vertical turbulent pipe flow was conducted. The main objective of the present article is to investigate the effects of dispersed phase (particles) on continuous phase (gas). In so doing, two general forms of Eulerian-Lagrangian approaches namely, one-way (when the fluid flow is not affected by the presence of the particles) and two-way (when the particles exert a feedback force on the fluid) couplings were used to describe the equations of motion of the two-phase flow. Gas-phase velocities which are within the order of magnitude as that of particles, volume fraction, and particle Stokes number were calculated and the results were subsequently compared with the available experimental data. The simulated results show that when the particles are added, the fluid velocity is attenuated. With an increase in particle volume fraction, particle mass loading and Stokes number, velocity attenuation also increases. Moreover, the results indicate that an increase in particle Stokes number reduces the special limited particle volume fraction, according to which one-way coupling method yields plausible results. The results have also indicated that the significance of particle fluid interaction is not merely a function of volume fraction and particle Stokes number.

Numerical Simulation of the Flow of Gases in a Large-Scale Electroslag Furnace

2011 ◽  
Vol 287-290 ◽  
pp. 970-973 ◽  
Author(s):  
Chen Yan ◽  
Ying Li ◽  
Ying Ying Zhai ◽  
Yu Hui Sha
Keyword(s):  
Numerical Simulation ◽  
Large Scale ◽  
Gas Flow ◽  
Volume Fraction ◽  
Cfd Modeling ◽  
Radiation Model ◽  
Argon Gas ◽  
Air Volume ◽  
Commercial Code ◽  
Protective Gas

This paper reports a CFD modeling study on the flow of gases in an electroslag furnace during Protective Gas Electroslag Remelting(PESR) process by a commercial code FLUENT. The Realizable k−ε turbulence model, Do radiation model and Mixture model are amply used in FLUENT code to compute the flow of gases in the furnace under different argon gas flow, and the influence of argon gas flow on air volume fraction in the furnace is obtained. Finally, a suited suggestion on argon gas flow during PESR process is presented.

scholarly journals Investigation on influences of loose gas on gas-solid flows in a circulating fluidized bed (CFB) reactor using full-loop numerical simulation

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Pengju Huo ◽  
Xiaohong Li ◽  
Yang Liu ◽  
Haiying Qi
Keyword(s):  
Numerical Simulation ◽  
Flow Rate ◽  
Gas Flow ◽  
Circulating Fluidized Bed ◽  
Separation Efficiency ◽  
Circulation Rate ◽  
Solid Mass ◽  
Gas Flow Rate ◽  
Gas Leakage ◽  
Mass Circulation

AbstractThe influences of loose gas on gas-solid flows in a large-scale circulating fluidized bed (CFB) gasification reactor were investigated using full-loop numerical simulation. The two-fluid model was coupled with the QC-energy minimization in multi-scale theory (EMMS) gas-solid drag model to simulate the fluidization in the CFB reactor. Effects of the loose gas flow rate, Q, on the solid mass circulation rate and the cyclone separation efficiency were analyzed. The study found different effects depending on Q: First, the particles in the loop seal and the standpipe tended to become more densely packed with decreasing loose gas flow rate, leading to the reduction in the overall circulation rate. The minimum Q that can affect the solid mass circulation rate is about 2.5% of the fluidized gas flow rate. Second, the sealing gas capability of the particles is enhanced as the loose gas flow rate decreases, which reduces the gas leakage into the cyclones and improves their separation efficiency. The best loose gas flow rates are equal to 2.5% of the fluidized gas flow rate at the various supply positions. In addition, the cyclone separation efficiency is correlated with the gas leakage to predict the separation efficiency during industrial operation.

Modeling Recrystallization for 3D Multi-Pass Forming Processes

2007 ◽  
Vol 558-559 ◽  
pp. 1201-1206 ◽  
Author(s):  
Mihaela Teodorescu ◽  
Patrice Lasne ◽  
Roland E. Logé
Keyword(s):  
Numerical Simulation ◽  
Grain Size ◽  
Present Model ◽  
Static Recrystallization ◽  
Volume Fraction ◽  
The Other ◽  
Finite Element Code ◽  
3D Numerical Simulation ◽  
Fraction Distribution ◽  
Simulation Results

The present work concerns the simulation of metallurgical evolutions in 3D multi-pass forming processes. In this context, the analyzed problem is twofold. One point refers to the management of the microstructure evolution during each pass or each inter-pass period and the other point concerns the management of the multi-pass aspects (different grain categories, data structure). In this framework, a model is developed and deals with both aspects. The model considers the microstructure as a composite made of a given (discretized) number of phases which have their own specific properties. The grain size distribution and the recrystallized volume fraction distribution of the different phases evolve continuously during a pass or inter-pass period. With this approach it is possible to deal with the heterogeneity of the microstructure and its evolution in multi-pass conditions. Both dynamic and static recrystallization phenomena are taken into account, with typical Avrami-type equations. The present model is implemented in the Finite Element code FORGE2005®. 3D numerical simulation results for a multi-pass process are presented.

Computational study of unsteady gas flow in the combustion chamber of a ramjet engine with heat transfer

2021 ◽  
pp. 50-61
Author(s):  
Надежда Петровна Скибина
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Supersonic Flow ◽  
Combustion Chamber ◽  
Gas Flow ◽  
Stokes Equations ◽  
Heat Conducting ◽  
Measuring Device ◽  
Ramjet Engine ◽  
Mach Numbers

Проведено численное исследование нестационарного турбулентного сверхзвукового течения в камере сгорания прямоточного воздушно-реактивного двигателя. Описана методика экспериментального измерения температуры на стенке осесимметричного канала в камере сгорания двигателя. Математическое моделирование обтекания исследуемой модели двигателя проводилось для скоростей набегающего потока M = 5 ... 7. Начальные и граничные условия задачи соответствовали реальному аэродинамическому эксперименту. Проанализированы результаты численного расчета. Рассмотрено изменение распределения температуры вдоль стенки канала с течением времени. Проведена оценка согласованности полученных экспериментальных данных с результатами математического моделирования. Purpose. The aim of this study is a numerical simulation of unsteady supersonic gas flow in a working path of ramjet engine under conditions identical to aerodynamic tests. Free stream velocity corresponding to Mach numbers M=5 ... 7 are considered. Methodology. Presented study addresses the methods of physical and numerical simulation. The probing device for thermometric that allows to recording the temperature values along the wall of internal duct was proposed. To describe the motion of a viscous heat-conducting gas the unsteady Reynolds averaged Navier - Stokes equations are considered. The flow turbulence is accounted by the modified SST model. The problem was solved in ANSYS Fluent using finite-volume method. The initial and boundary conditions for unsteady calculation are set according to conditions of real aerodynamic tests. The coupled heat transfer for supersonic flow and elements of ramjet engine model are realized by setting of thermophysical properties of materials. The reliability testing of numerical simulation has been made to compare the results of calculations and the data of thermometric experimental tests. Findings. Numerical simulation of aerodynamic tests for ramjet engine was carried out. The agreement between the results of numerical calculations and experimental measurements for the velocity in the channel under consideration was obtained; the error was shown to be 2%. The temperature values were obtained in the area of contact of the supersonic flow with the surface of the measuring device for the external incident flow velocities for Mach numbers M = 5 ... 7. The process of heating the material in the channel that simulated the section of the engine combustion chamber was analyzed. The temperature distribution was studied depending on the position of the material layer under consideration relative to the contact zone with the flow. Value. In the course of the work, the fields of flow around the model of a ramjet engine were obtained, including the region of supersonic flow in the inner part of axisymmetric channel. The analysis of the temperature fields showed that to improve the quality of the results, it is necessary to take into account the depth of the calorimetric sensor. The obtained results will be used to estimate the time of interaction of the supersonic flow with the fuel surface required to reach the combustion temperature.

scholarly journals Flow topologies in bubble-induced turbulence: a direct numerical simulation analysis

2018 ◽  
Vol 857 ◽  
pp. 270-290 ◽  
Author(s):  
Josef Hasslberger ◽  
Markus Klein ◽  
Nilanjan Chakraborty
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Turbulent Flows ◽  
Volume Fraction ◽  
Fluid Velocity ◽  
Small Scale ◽  
Flow Topology ◽  
Two Phase ◽  
Local Flow ◽  
Interface Curvature

This paper presents a detailed investigation of flow topologies in bubble-induced two-phase turbulence. Two freely moving and deforming air bubbles that have been suspended in liquid water under counterflow conditions have been considered for this analysis. The direct numerical simulation data considered here are based on the one-fluid formulation of the two-phase flow governing equations. To study the development of coherent structures, a local flow topology analysis is performed. Using the invariants of the velocity gradient tensor, all possible small-scale flow structures can be categorized into two nodal and two focal topologies for incompressible turbulent flows. The volume fraction of focal topologies in the gaseous phase is consistently higher than in the surrounding liquid phase. This observation has been argued to be linked to a strong vorticity production at the regions of simultaneous high fluid velocity and high interface curvature. Depending on the regime (steady/laminar or unsteady/turbulent), additional effects related to the density and viscosity jump at the interface influence the behaviour. The analysis also points to a specific term of the vorticity transport equation as being responsible for the induction of vortical motion at the interface. Besides the known mechanisms, this term, related to surface tension and gradients of interface curvature, represents another potential source of turbulence production that lends itself to further investigation.

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