• Title/Summary/Keyword: FCT(Flux-Corrected Transport)

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Performance Prediction of SCR-DeNOx System for Reduction of Diesel Engine NOx Emission (디젤엔진의 NOx 저감을 위한 SCR-DeNOx 후처리 시스템 성능 예측)

  • 김만영
    • Transactions of the Korean Society of Automotive Engineers
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    • v.11 no.3
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    • pp.71-76
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    • 2003
  • A numerical simulation of selective catalytic reduction (SCR) for NO with $NH_3$ is conducted over the $V_2O_5/TiO_2$ and $WO_3-V_2O_5/TiO_2$ catalysts. The governing $NH_3$ and NO transport equations are considered by using the time-dependent FCT (Flux-Corrected Transport) algorithm. After a validating simulation for $NH_3$ step feed and shut-off experiments is analyzed, transient behavior of $NH_3$ and NO concentration in a SCR catalyst is investigated by changing such parameters as inflow $NH_3$ concentration, temperature of the catalyst, and $NH_3$/NOx ratios.

A Quasi Two-Dimensional Model for Gas Discharge Simulation Using FE-FCT Method (기체 방전의 시뮬레이션을 위한 FE-FCT를 이용한 준 2차원적 수치 모델)

  • Koh, Wook-Hee;Park, In-Ho
    • Journal of the Korean Vacuum Society
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    • v.17 no.6
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    • pp.511-517
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    • 2008
  • A quasi two-dimensional model for numerical simulation of gas discharge is presented, based on the finite-element flux-corrected transport method. A one-dimensional continuity convection-diffusion equation coupled Poisson's equation is solved to calculate the charge density variation and the electric field is evaluated by the classical disk method. Results calculated for various benchmark problems verify the accuracy of the proposed model and illustrate its performance. This model has been applied to a streamer simulation, and the results are shown to agree well with previously published results.

A Study on the Corona Discharge Simulation Using FEM-FCT Method (FEM-FCT 기법을 이용한 코로나 방전 시뮬레이션에 대한 연구)

  • Min, Ung-Gi;Kim, Hyeong-Seok;Lee, Seok-Hyeon;Han, Song-Yeop
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.48 no.3
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    • pp.200-208
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    • 1999
  • In this paper, the corona discharge is analyzed by Finite Element Method(FEM) combined with Flux-corrected Transport(FCT) algorithm. In the previous papers, Finite Difference Method(FDM) combined with FCT was used. Usually in the FDM, the regionof interest is discretized with structured grids. But to refine local regions with same resolution, much more grids are required for the structured grids than for unstructured grids than for unstructured grids. Therefore, we propose the FEM-FCT method to simulate the corona discharge. The proposed method has good flexibility in model shape and can reduce the computational cost by the local refinement where the physical quantities have steep gradients. Using the proposed method, we study the streamer growth of parallel plate electrodes which is initiated by the low and high perturbation density. We find that the varying the initial density of perturbation has very little effect on the streamer propagation. And the corona discharge of the rod-to-plane electrode is simulated. On the surface of the rod electrode, the high concentration of the electric field gives rise to many number of streamer seeds. The strong axial streamer propagate to the plane electrode. The weaker non-axial streamer repel each other and stop growing more. The results are very similar to those of the papers which used the FDM-FCT method on structured grids. Thus we can conclude that the proposed FEM-FCT method is more efficient than the conventional FDM-FCT method by virtue of the reduction in computational grids number.

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Numerical Simulation of Intake and Exhaust Flows and Noise in 4 Stroke S.I. Engine using the Lax-Wendroff Method (Lax-Wendroff 방법을 이용한 4행정 전기점화 기관의 흡.배기관내의 유동 및 소음특성 해석)

  • 정수진
    • Journal of Advanced Marine Engineering and Technology
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    • v.22 no.5
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    • pp.693-701
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    • 1998
  • This study presents result of comparison between two other numerical method method of char-acteristics(MOC) and Lax-Wendroff method(LWM) applied at wave action analysis of intake and exhaust pipe in terms of calculated pressure velocity and emitted noise in the time and the fre-quency domain by means of fast Fourier transform analysis. Particularly FCT(Flux Corrected Transport)scheme is appended to LWM to protest unaceptable overshoots occurring near discon-tinuity. The final conclusion of this study is that MOC should be replaced by a second order finite difference approach because of larger contributions due to high frequency components than the results from the method of characteristics. Clear benefits we can get by change are faster calcula-tion higher accuracy conservation of mass and consistent calculation method.

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Numerical Simulation of Nitrogen Discharge at Medium Pressure between Point-Plane Electrodes (침-평판 전극 사이에서 중간 압력 질소 방전의 시뮬레이션)

  • Koh, Wook-Hee;Park, In-Ho
    • Journal of the Korean Vacuum Society
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    • v.17 no.6
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    • pp.487-494
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    • 2008
  • The numerical simulation of point-to-plane discharge of nitrogen at medium pressure has been achieved by a quasi-2d numerical model. In the model, we calculate the distributions of electric charges which are varying as temporal and space and determine the electric field depending on space charge distribution by solving Poisson's equation. The continuity equations are treated numerically by using FCT (Flux-Corrected Transport) Algorithm and FEM (Finite Element Method). The numerical simulation results make us to understand the physical characteristics of nitrogen discharge at 50 torr. The comparison with experimental results[1] shows a good qualitative agreement.

A Calculation of 1 Dimensional Blasting Pressure Uslng the Flux-Corrected Transport Algorithm (Flux-Corrected Transport Algorithm을 적용한 1차원 발파압력산정에 관한 연구)

  • 김문겸;오금호;이필규
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1995.10a
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    • pp.76-83
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    • 1995
  • Estimation of blasting behavior of explosives is prerequisite in the numerical analysis of blasting works. In this study, blasting pressure is estimated by the finite difference method using the Flux-Corrected Transport Algorithm. To formulate the behavior of blasting gas, the mass conservation equation, the moment conservation equation, the energy conservation equation and the ideal gas state equation are used. The simplified species conservation equation is included to simulate the behavior of reacting explosives. To verify the calculation, the Sod's shock tube problem, the strong shock problem and the reacting problem we used. Numerical results show that the shock wave can be captured by means of the FCT algorithm in the reacting and nonreacting states.

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A study on 2-dimensional simulation of AC PDP using FEM-FCT method (FEM-FCT 기법을 이용한 AC PDP 2차원 시뮬레이션에 관한 연구)

  • Kim, Yong-Jin;Min, Woong-Gee;Lee, Seok-Hyun
    • Proceedings of the KIEE Conference
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    • 2000.11c
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    • pp.565-567
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    • 2000
  • In this paper, the discharge characteristics of AC PDP, one of the leading technologies currently under development for large-area flat displays, is computed by using Finite Element Method(FEM) combined with Flux-corrected Transport(FCT) algorithm. Up to now, many simulations of AC PDP have been mainly done by Finite Difference Method(FDM). But we simulated the AC PDP by using FEM-FCT method which discretizes the region of interest with unstructured grids. FEM-FCT method can reduce the computational cost because of refining locally where the physical quantities have steep gradients and is more efficient in solving discharge problems, such as a AC PDP. Results are presented in Ne-Xe(4%) gas mixture for a gas pressure of 400 Torr and as the discharge proceeds, the space and time variations of the electron and ion densities, potential and wall charges on the dielectric are described. Results from our simulation by FEM-FCT are similar to those from simulation by FDM and are more efficient in computational cost reduction.

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Numerical Simulation of Corona Streamer Using Adaptive Mesh Generation and FEM-FCT Method (적응요소분할기법과 FEM-FCT를 이용한 코로나 스트리머 해석)

  • Min, Woong-Gee;Kim, Hyeong-Seok;Lee, Seok-Hyun;Hahn, Song-Yop
    • Proceedings of the KIEE Conference
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    • 1999.07e
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    • pp.2044-2046
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    • 1999
  • In this paper, the propagation of corona streamer was simulated using finite element method(FEM) combined with Flux-Corrected Transport(FCT) algorithm. To obtain more effective grid distribution, the adaptive mesh generation scheme was also employed. The employed adaptive scheme can refine the mesh where needed. In addition, it is possible to coarsen the unnecessarily dense mesh. Two models were analyzed with proposed method. And the results are shown.

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Study of Characteristics of Corona Discharge Plasma in a Wire-Cylinder Type Reactor (Wire-Cylinder형 반응로에서의 코로나 방전 플라스마의 특성 연구)

  • 박승자;박인호;고욱희
    • Journal of the Korean Vacuum Society
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    • v.13 no.3
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    • pp.132-138
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    • 2004
  • We used the self-consistent one-dimensional model applied to FCT algorithm and FEM method in a wire-cylinder type reactor to study the characteristics of corona discharge plasma in air at the atmospheric pressure. At the pulsed do voltage and do voltage, we studied the changes of the characteristic of plasma by computing electron density profile according to the changes of voltage and the size of reactor. The changes of active radius from this result are compared with the data of Peek's. The numerical simulation results for a corona discharge plasma explain the physical mechanism of the discharge process and could be used to obtain the optimized parameters for designing the plasma reactor for pollution abatement.

The Analysis of the Negative Streamer Including Photoionization Effect (광전리효과를 고려한 음극성 스트리머 해석)

  • Song, Bong-Shik;Min, Woong-Kee;Lee, Seok-Hyun
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.50 no.5
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    • pp.232-237
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    • 2001
  • The transition avalanche to streamer are presented in atmospheric pressure nitrogen. The results of two-dimensional simulation are obtained by using finite Elements Method combined with Flux Corrected Transport algorithm(FEM-FCT). We modeled the negative streamer which enables to propagate with out and with photoionization. The results of simulation without photoionization and with photoionization are compared. We show that photoionization plays important roles not only in streamer formation but also in streamer propagation.

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