• Title/Summary/Keyword: 3-D combustion model

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1D and 3D Thermoacoustic Combustion Instability Modeling (1D 및 3D 열음향 연소불안정 모델링)

  • Kim, Jin Ah;Lim, Jaeyoung;Kim, Jihwan;Pyo, Yeongmin;Kim, Deasik
    • 한국연소학회:학술대회논문집
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    • 2015.12a
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    • pp.113-114
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    • 2015
  • In this study, 1D and 3D thermoacoustic analysis model were developed in order to predict fundamental characteristics of combustion instability in a gas turbine lean premixed combustor. The 1D network model can be used to analyze frequency and growth rate of combustor instability by simply dividing whole system into a couple of acoustic sub-elements, while the 3D Helmholtz solver model can predict directly acoustic modes as well as basic properties of combustion instability. Prediction results of both 1D and 3D models generally showed a good agreement with the measurements, even if there was a slight overestimation for instability range.

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Combustion Modeling for Stratified Charge (성층화 혼합기의 연소 모델링)

  • 김용태;배상수;민경덕
    • Transactions of the Korean Society of Automotive Engineers
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    • v.9 no.4
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    • pp.50-55
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    • 2001
  • To simulate the combustion process under stratified charged conditions, like GDI engines, the new combustion model is proposed, which is based on Welter's FAE model and Peters' PDF model for considering primary reactions. In addition to these models, the new laminar burning velocity correlation and diffusion flame model are also included in the proposed model. The former can be applicable to much wider range of equivalence ratio, pressure and temperature than the others, such as Keck's and Guilder's models, and the latter has been derived from water-gas shift reaction and hydrogen oxidation, by which the secondary reactions can be considered after primary reactions. 3-D computation has been performed by using STAR-CD v3.05 in the simple cylindrical geometry under stratified charged condition. Judging from the calculated results, the present model proves to be reasonable to simulate the characteristics of flame propagation and concentrations of products in burned regions.

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GOTHIC-3D APPLICABILITY TO HYDROGEN COMBUSTION ANALYSIS

  • LEE JUNG-JAE;LEE JIN-YONG;PARK GOON-CHERL;LEE BYUNG-CHUL;YOO HOJONG;KIM HYEONG-TAEK;OH SEUNG-JONG
    • Nuclear Engineering and Technology
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    • v.37 no.3
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    • pp.265-272
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    • 2005
  • Severe accidents in nuclear power plants can cause hydrogen-generating chemical reactions, which create the danger of hydrogen combustion and thus threaten containment integrity. For containment analyses, a three-dimensional mechanistic code, GOTHIC-3D has been applied near source compartments to predict whether or not highly reactive gas mixtures can form during an accident with the hydrogen mitigation system working. To assess the code applicability to hydrogen combustion analysis, this paper presents the numerical calculation results of GOTHIC-3D for various hydrogen combustion experiments, including FLAME, LSVCTF, and SNU-2D. In this study, a technical base for the modeling oflarge- and small-scale facilities was introduced through sensitivity studies on cell size and bum modeling parameters. Use of a turbulent bum option of the eddy dissipation concept enabled scale-free applications. Lowering the bum parameter values for the flame thickness and the bum temperature limit resulted in a larger flame velocity. When applied to hydrogen combustion analysis, this study revealed that the GOTHIC-3D code is generally able to predict the combustion phenomena with its default bum modeling parameters for large-scale facilities. However, the code needs further modifications of its bum modeling parameters to be applied to either small-scale facilities or extremely fast transients.

Dual-Fuel Combustion Phenomena of Pilot Distillate Injected to Pre-mixed Natural Gas in a Constant Volume Combustion Bomb (천연가스가 예혼합된 정적연소실에 파일럿오일을 분사한 복합연소현상)

  • Choi, I.S.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.3 no.6
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    • pp.112-122
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    • 1995
  • As an alternative fuel producing less exhaust emissions, natural gas is of interest for use both in SI and CI engines. The potential of natural gas fuelled dual-fuel engine is considered high enough. However, much effort has to be made so that gaseous fuel is used efficiently with simultaneous minimum use of pilot oil. Hence, a simplified three-dimensional model, using a finite volume method in cylindrical coordinates, has been developed to facilitate an understanding of the dual-fuel combustion phenomena and to predict the complex interactions between the pilot distillate and natural gas. The computer model was calibrated by comparing it with the experimental results obtained from diesel engine like combustion bomb tests. In the pre-mixed natural gas combustion, the fuel burning was highly reliant on the injection condition and subsequent burning nature of the pilot distillate.

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Effects of Aspect Ratio on Combustion Characteristics in Diesel Engine (연소실 형상비가 디젤기관의 연소특성에 미치는 영향)

  • Kwon, S.I.;Kwon, J.B.;Kim, H.S.
    • Journal of ILASS-Korea
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    • v.3 no.3
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    • pp.23-32
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    • 1998
  • The effect of reentrant type bowl geometry on combustion characteristics was investigated in a D.I. diesel engine. The main factor was the aspect ratio (Bowl Diameter / Bowl Depth) of bowl of combustion chamber, and the cylinder pressure, engine performance and emissions of the engine using the 4 kinds of the combustion chamber were meadured. Also, the combustion characteristics compared of the experimented and the calculated values which is used by the Hiroyasu's combustion model. The results are as follows; The effect of $d_c/H$ on ignition delay period are small. The smoke is corerelated to the heat release of the premixed and the diffusion combustion, i.g, the smoke decreased by decreasing the premixed combustion or increasing the diffusion combustion on cumulative heat release. The premixed combustion process has more effect than the diffusion combustion on smoke. The formal tendency of $d_c/H$ on engine performance has not appear.

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Comparison of the combustion characteristics between air combustion and oxy-combustion with $CO_2$ recirculation ($CO_2$ 재순환에 의한 순산소 연소와 공기 연소의 화염 특성 비교)

  • Lee, Seung-Hwan;Huh, Kang-Y.
    • Journal of the Korean Society of Combustion
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    • v.13 no.3
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    • pp.24-32
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    • 2008
  • Steady Laminar Flamelet Model (SLFM) calculation is performed to compare the turbulent combustion characteristics of air combustion and oxy-combustion with $CO_2$ recirculation. Radiative heat loss is considered by the optically thin limit assumption. For more realistic simulation the first-order conditional moment closure(CMC) model is applied to SANDIA PILOTED FLAME D again for the oxidants of air and mixture of $O_2$ and $CO_2$. The chemical kinetic machanism for methane is GRI Mech 3.0. Results show that oxy flames are much more stable than air flames, while comparable stability is maintained with 65% $CO_2$ recirculation. The comparable peak temperature is maintained with 80% $CO_2$ recirculation. Higher the temperature, higher the fractions of intermediate species, CO and OH, due to dissociation.

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Study of the Radiation Effect by Equivalence ratio change on the 3-D Turbulent Combustion (당량비 변화에 따른 복사 특성이 3차원 난류 연소에 미치는 영향 연구)

  • Kim, Tea-Kuk;Yoon, Kyung-Beom;Min, Dong-Ho;Chang, Hee-Chul;Kim, Jin-Soo
    • 한국연소학회:학술대회논문집
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    • 2006.10a
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    • pp.79-85
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    • 2006
  • Radiative heat transfer is very important in many combustion systems since they are operated in high temperature. Fluid flows in most of the combustion systems are turbulent to promote fast mixing of the hydrocarbon fuel and oxidant. Major combustion products are $CO_2$ and $H_2O$. The turbulent flow is modeled by using the standard ${\kappa}-{\epsilon}$ model and the radiation transfer is modeled by using the discrete ordinates method where the radiative gas properties are calculated by using the weighted sum of gray gases model with a gray gas regrouping(WSGGM-RG). Effect of the radiation on the combustion characteristics in a three-dimensional rectangular enclosure is studied by changing the equivalence ratio. Results show that the radiation plays a significant role on the heat transfer in the combustion systems by resulting in a temperature drop of 16% as compared to that obtained without radiation. The equivalence ratio also affects the combustion by different contribution of the radiative transfer with different gas compositions.

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Modeling the Dual-Fuel Combustion of Natural Gas and Pilot Distillate Injected Directly into a Diesel Combustion Bomb (디젤연소용기에 직접분사된 천연가스와 파일럿오일의 복합연소 모델링)

  • 최인수
    • Transactions of the Korean Society of Automotive Engineers
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    • v.4 no.1
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    • pp.155-164
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    • 1996
  • Dual-fuel engines are being researched with emphasis on the possible types of natural gas supply systems. Hence, a three-dimensional combustion model by using finite volume method was developed to provide a fundamental understanding of the auto-ignition of pilot distillate and subsequent burning of natural gas, when the natural gas as well as the distillate was directly injected into a quiescent diesel engine like combustion bomb tests and the numerical results were investigated for the mixed combustion phenomena. With high-pressure natural gas injection, it was found that the gaseous fuel injection characteristics had to be well harmonised with that of the pilot distillate. For better combustion efficiency, however, further researches are required for the optimisation of injection system in the existence of air motion.

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Temperature transients of piston of a Camless S.I Engine using different combustion boundary condition treatments

  • Gill, KanwarJabar Singh;Singh, Khushpreet;Cho, H.M.;Chauhan, Bhupendra Singh
    • Journal of Energy Engineering
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    • v.23 no.3
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    • pp.221-230
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    • 2014
  • Simplified finite element model of spark ignition (SI) engine to analyse combustion heat transfer is presented. The model was discredited with 3D thermal elements of global length 5 mm. The fuel type is petrol. Internal nodal temperature of cylinder body is defined as 21000C to represent occurrence of gasoline combustion. Material information and isotropic material properties are taken from published report. The heat transfer analysis is done for the instant of combustion. The model is validated by comparing the computed maximum temperature at the piston surface with the published result. The computed temperature gradient at the crucial parts are plotted and discussed. It has been found that the critical top surface suffered from thermal and the materials used to construct the engine parts strongly influenced the temperature distribution in the engine. The model is capable to analyze heat transfer in the engine reasonably and efficiently.

NUMERICAL ANALYSIS TO DESIGN HIGH TEMPERATURE HEAT EXCHANGER OF BETA TYPE STIRLING ENGINE IN 3-D COMBUSTION FIELD (3차원 연소장에서의 베타 형태의 스털링엔진 고온 열교환기 설계를 위한 수치해석 연구)

  • Kang, S.H.;Kim, H.J.;Chung, D.H.
    • Journal of computational fluids engineering
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    • v.16 no.2
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    • pp.56-61
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    • 2011
  • Numerical study is conducted to design the high temperature heat exchanger of Stirling engine by using the commercial CFD solver, FLUENT. The Fin-tube type of heat exchanger is designed as a reference model by considering the type of engine which is ${\beta}$-configuration. To find the optimal design of heat exchanger in heat transfer capacity numerical calculation is conducted by changing the shape, the number, and material of reference model in three-dimensional combustion field. Adjusted one-way constant velocity of working fluid that is helium is considered as the representative velocity of oscillating flow. The optimal design of heat exchanger considering the heat transfer capability is suggested by using the calculation results.