• 한국연소학회:학술대회논문집
• /
• 한국연소학회 제26회 KOSCO SYMPOSIUM 논문집
• /
• pp.57-62
• /
• 2003

A general procedure of obtaining reliable one-step kinetics model for hydrocarbon mixture from the fully detailed chemistry is described iin this study. One-step theoretical formulation of the induction parameter model IPM uses a theoretical reconstruction of the induction time database obtained from a detailed kinetics library. Non-dimensional induction time calculations is compared with that of detailed kinetics. The IPM was latter implemented to fluid dynamics code and applied for the numerical simulation of detonation wave propagation. The numerical results including the numerical smoked-foil record show the all the details of the detonation wave propagation characteristics at the cost around 1/100 of the detailed kinetics calculation.

• 한국항공우주학회지
• /
• 제37권4호
• /
• pp.383-391
• /
• 2009

JP-7/산소 혼합기의 데토네이션 파 특성을 상세 반응 기구로부터 얻은 일 단계 유도 변수 모델을 (IPM) 이용하여 살펴보았다. 탄화수소 혼합기에 대한 상세 화학 반응 모델로 부터 신뢰할 만한 일 단계 반응 모델을 얻기 위한 일반적 과정을 본 연구에서 제시하였다. IPM은 상세 반응 모델 라이브러리로부터 획득한 유도 시간 데이터베이스를 재구성하여 얻었으며, 상세 반응 모델에 의한 결과와 비교하여 확인하였다. 이후 IPM을 유체역학해석 코드에 적용하였으며, 데토네이션 파 전파에 대한 수치해석에 이용하였다. 수치해석 결과는 탄화수소 연료 연소의 상세 반응 기구를 직접 적용해서는 가능하지 않은, JP-7/산소 혼합기의 데토네이션 파 전파 특성의 상세한 특징을 보여주었다.

• 한국연소학회지
• /
• 제13권1호
• /
• pp.17-22
• /
• 2008

A partly implicit/quasi-explicit method is introduced for the solution of detailed chemical kinetics with stiff source terms based on the standard fourth-order Runge-Kutta scheme. Present method solves implicitly only the stiff reaction rate equations, whereas the others explicitly. The stiff equations are selected based on the survey of the chemical Jaconian matrix and its Eigenvalues. As an application of the present method constant pressure combustion was analyzed by a detailed mechanism of hydrogen-air combustion with NOx chemistry. The sensitivity analysis reveals that only the 4 species in NOx chemistry has strong stiffness and should be solved implicitly among the 13 species. The implicit solution of the 4 species successfully predicts the entire process with same accuracy and efficiency at half the price.

• 한국연소학회지
• /
• 제16권4호
• /
• pp.38-45
• /
• 2011

Coal-derived syngas has been utilized by main fuel at IGCC power plant. Research efforts for investigating the characteristics of premixed and nonpremixed flames at gas-turbine condition have been conducted. The present study has been mainly motivated to evaluate the capability of the detailed chemical kinetics to predict the syngas laminar flame speed. Special emphasis is given to the effects of pressure, temperature, syngas composition, and dilution level on the characteristics of premixed and nonpremixed flames. The predicative capability of a number of detailed mechanism for laminar flame speed is compared to experimental data. From these results, detailed kinetics of Davis et al. and Li et al. have the best conformity with the experiments in the all the case of parametric studies.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2007년도 제28회 춘계학술대회논문집
• /
• pp.143-147
• /
• 2007

케로신과 디젤은 단일 구성물이 아닌 여러 가지 탄화수소 연료로 이루어진 혼합연료이며 화학반응 메커니즘에 대한 모델링이 매우 어려운 실정이다. 본 연구에서는 Dagaut가 개발한 298 화학종, 2352 화학반응 단계를 이용하였으며 완전혼합반응기 연소모델을 적용하여 농후 연소 비평형 화학 반응을 계산하였다. 또한 Frenklach의 soot 모델을 적용하여 soot 생성 연구를 수행하였으며 Dagaut의 화학반응 모델에 Appel이 제안한 화학 반응 단계를 추가하여 케로신과 디젤 연료에 대한 soot 모사를 가능하게 하였으며 수정된 모델은 간단한 soot 반응 메커니즘을 사용하였음에도 불구하고 soot 생성 예측이 가능하였다.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2006년도 제27회 추계학술대회논문집
• /
• pp.150-153
• /
• 2006

액체 로켓 엔진의 가스발생기는 터빈 블레이드의 열적 손상을 막기 위해 온도의 제한이 있으며 이를 위해 농후 또는 희박 연소를 하게 된다. 따라서 비평형 화학 반응이 주로 발생하며 이를 해석하는 것은 매우 어렵다. 본 연구에서는 케로신과 액체산소를 추진제로 하는 가스발생기에 대하여 Dagaut이 제안한 상세 화학 반응 단계를 사용하여 완전 혼합 반응기 연소 모델의 수정을 통해 계산하였으며, Frenklach의 soot 모델을 적용하여 예측 결과의 몰 분율, 가스 물성치 등의 결과에 대한 개선 방향을 제시하였다.

• 대한기계학회논문집B
• /
• 제21권9호
• /
• pp.1126-1138
• /
• 1997

An axisymmetric laminar jet diffusion flame has been numerically modelled. The present study employs the refined physical submodels to account for the detailed chemical kinetics and the variable transport properties. It is found that preferential diffusion resulting from variable transport properties significantly influences the hydrogen diffusion flame structure in terms of the spatial distribution for temperature, species concentration, thermal and mass diffusivity, Lewis number, and NO concentration. The preferential diffusion effects on the diffusion flame in the high-pressure environment are also discussed in detail.

• 한국자동차공학회논문집
• /
• 제11권6호
• /
• pp.51-58
• /
• 2003

A cycle simulation method is developed by coupling a commercial code, Ricardo's WAVE, with the SENKIN code from CHEMKIN packages to predict combustion characteristics of an HCCI engine. By solving detailed chemical kinetics the SENKIN code calculates the combustion products in the combustion chamber during the valve closing period, i.e. from IVC to EVO. Except the combustion chamber during the valve closing period the WAVE code solves thermodynamic status in the whole engine system. The cycle simulation of the complete engine system is made possible by exchanging the numerical solutions between the codes on the coupling positions of the intake port at IVC and of the exhaust port at EVO. This method is validated against the available experimental data from recent literatures. Auto ignition timing and cylinder pressure are well predicted for various engine operating conditions including a very high ECR rate although it shows a trend of sharp increase in cylinder pressure immediate after auto ignition. This trend is overpredicted especially for EGR cases, which may be due to the assumption of single-zone combustion model and the limit of the chemical kinetic model for the prediction of turbulent air-fuel mixing phenomena. A further work would be needed for the implementation of a multi-zone combustion model and the effect of turbulent mixing into the method.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2011년도 추계학술대회 초록집
• /
• pp.99.1-99.1
• /
• 2011

Reactant mixing has a critical role in ensuring reformate quality and an important design objective is to achieve sufficiently complete mixture of reactants. For that purpose it is required to understand the coupled transport-kinetics phenomena in the mixing region. Three-dimensional computational fluid dynamics model was developed and validated in previous works. The mixing characteristics in various alternatives of a prototype mixing chamber were compared, and then a reduced reaction kinetics was applied to two extreme designs for investigating the impact of gas-phase reactions. Both designs did not reach threshold ethylene mole fraction of 0.001, but surprisingly more ethylene was generated in the design having better mixing characteristics. The presentation will deliver the development process of coupled transport and kinetics model briefly and the detailed information about the mixing characteristics and gas-phase reactions in two mixer designs.

• 대한기계학회논문집B
• /
• 제31권12호
• /
• pp.1009-1016
• /
• 2007

Numerical study on preferential diffusion effects in flame structure in $CH_4-H_2$ diffusion flames is conducted with detailed chemistry. Comparison of flame structures with mixture-averaged species diffusion and suppression of the diffusivities of $H_2$ and H was made. Discernible differences in flame structures are displayed with three species diffusion models. The behaviors of maximum flame temperatures with those species diffusion models are not explained by scalar dissipation rate but by the nature of chemical kinetics. It is seen that the modifcation of flame structure is mainly due to the preferential diffusion of H2 and thereby the nature of chemical kinetics. It is also found that the behaviors of major species with the three species diffusion models are addressed to the nature of chemical kinetics, and this is evident by examining importantly contributing reaction steps to the production and destruction of those chemical species.