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조덕래(Deok-Rae Cho),원수희(Su-Hee Won),신재렬(Jae-Ryul Shin),이수한(Soo-Han Lee),최정열(Jeong-Yeol Choi) 한국추진공학회 2007 한국추진공학회지 Vol.11 No.1
Three dimensional structures of detonation waves propagating in a square tube were investigated using a high resolution CFD code coupled with a conservation equation of reaction progress variable and an one-step irreversible reaction. The code were parallelized based on domain decomposition technique using MPI library. The computations were carried on an in-house Windows cluster with AMD processors. Three-dimensional unsteady analysis results in the smoked-foil records caused by the instabilities of the detonation waves, which showed the rectangular and diagonal modes of detonation instabilities depending on the initial condition of disturbances and the spinning detonation for case of small reaction constant.
Induction Parameter Modeling을 이용한 열 분해된 JP-7 연료 /산소 혼합기의 데토네이션 파 해석
조덕래(Deok-Rae Cho),신재렬(Jae-Ryul Shin),최정열(Jeong-Yeol Choi),Vigor Yang 한국항공우주학회 2009 韓國航空宇宙學會誌 Vol.37 No.4
JP-7/산소 혼합기의 데토네이션 파 특성을 상세 반응 기구로부터 얻은 일 단계 유도변수 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. The detonation wave characteristics of JP-7 and oxygen mixture is investigated by one-step induction parameter model (IPM) obtained from a detailed chemistry mechanism. A general procedure of obtaining reliable one-step kinetics IPM for hydrocarbon mixture from the fully detailed chemistry is described in this study. The IPM is obtained by the reconstruction of the induction time database obtained from a detailed kinetics library. The IPM was confirmed by the comparison of the induction time calculations with that from detailed kinetics. The IPM is later implemented to a fluid dynamics code and applied for the numerical simulation of detonation wave propagation. The numerical results show the detailed characteristics of the detonation wave propagation in JP-7 and oxygen mixture at affordable computing time, which is not be possible by the direct application of the detailed chemical kinetics mechanism of hydrocarbon fuel combustion.
고불안정 조건에서의 3차원 데토네이션 파면 구조 해석 연구
조덕래(Deok-Rae Cho),원수희(Su-Hee Won),신재렬(Jae-Ryul Shin),최정열(Jeong-Yeol Choi) 한국연소학회 2012 KOSCOSYMPOSIUM논문집 Vol.- No.45
The results are shown highly unstable mode"s detonation dynamics by compared with weakly unstable mode. And we investigate the difference and similar features of 2D and 3D results. By using PSD via FFT, the effects of pre-exponential factor difference and of unstable mode were investigated in this study. The result of PSD is shown pulsed features in weakly unstable mode, but noselike in highly unstable mode. By compared between Sheliren image and overlaid slice image, the irregular feature of detonation waves structure was discussed in highly unstable mode.
원형관 내 데토네이션 파 구조 및 동적 특성 수치 연구
조덕래(Deok-Rae Cho),김종관(Jong-Kwan Kim),장근진(Keun-Jin Jang),최정열(Jeong-Yeol Choi) 한국추진공학회 2012 한국추진공학회 학술대회논문집 Vol.2012 No.5
펄스 데토네이션 엔진과 같이 원형 관내를 전파하는 데토네이션 파의 삼차원 파면 구조 및 동적 특성을 파악하기 위한 수치 해석을 수행하였다. 비가역 Arrhenius 반응 모델을 이용하여 일련의 pre-exponential 값에 대한 해석을 수행하여 2-셀,3-셀, 4-셀 및 6-셀 데토네이션 모드의 삼차원 파면구조에 대한 생성 매커니즘들을 살펴보았다. 2차원 결과와 비교하여 반경 방향에서 slapping 횡단 파의 효과를 확인하였으며, 모든 다중-셀 모드에서 벽면에서의 데토네이션 파면 구조와 그을음 막 기록들은 반경 방향으로 slapping 파가 움직이는 동안 시계 및 반 시계 방향으로 움직이는 횡단파에 의하여 형성되며, 굽어진 벽면에서 반사되는 횡단파는 다차원 confinement 효과에 의하여 강도가 변화한다. Numerical studies were performed to investigate the three-dimensional front structure and dynamics features of detonation wave propagating in a circular tube such as Pulse Detonation Engine (PDE). By carrying out a series of parametric study using one step irreversible Arrhenius kinetics model, mechanisms of the three-dimensional front structure were investigated for two-, three-, four and six-cell mode detonations. A comparison with two-dimensional results, the effects of slapping transverse waves in radial direction were confirmed. In the all muti-cell modes, the detonation front structures and smoked-records on the wall are formed by the propagation of transverse waves along the wall in clockwise and counter-clockwise while the slapping move in radial direction. And the strength of reflected waves on the curved wall is changed by the multi-dimensional confinement effect.
Spinning Detonation 파의 3차원 수치 해석
조덕래(Deok-Rae Cho),최정열(Jeong-Yeol Choi),원수희(Su-Hee Won) 한국연소학회 2006 KOSCOSYMPOSIUM논문집 Vol.- No.-
Three-dimensional numerical study was carried out for the investigation of the detonation wave structures propagating in tubes. Fluid dynamics equations and conservation equation of reaction progress variable were analyzed by a MUSCL-type TVD scheme and four stage Runge- Kutta time integration. Chemical reaction was modeled by using a simplified one-step irreversible kinetics model. The variable gas properties between unburned and burned states were considered by using variable specific heat ratio formulation. The unsteady computational results in three-dimension show the detailed mechanisms of rectangular and diagonal mode of detonation wave instabilities resulting same cell length but different cell width in smoked-foil record. The results for the small reaction constant shows the spinning mode of three-dimensional detonation wave dynamics, which was rarely observed in the previous numerical simulation of the detonation waves.
이수한(Su-Han Lee),조덕래(Deok-Rae Cho),최정열(Jeong-Yeol Choi) 한국추진공학회 2008 한국추진공학회지 Vol.12 No.2
Present study examines the detonation wave propagation characteristics in annular channels. Numerical approaches used in the previous studies were extended with marching windows technique. Parametric study has been carried out using a radius of curvature normalized by the channel width considered as unique geometric parameter. In the channels of small radius of curvature, detonation wave is unstable and the regular cell structure is not observed. There is a critical radius of curvature where cell structure can be sustained. The effect of curvature makes the pressure difference on inner and outer surfaces where the detonation wave is overdriven. The results converge to that of straight channel as the radius of curvature gets larger, as expected.
Viscous and Diffusion Effects in the Numerical Simulation of Highly Unstable Detonation Phenomena
최정열(Jeong-Yeol Choi),조덕래(Deok-Rae Cho) 한국연소학회 2011 KOSCOSYMPOSIUM논문집 Vol.- No.42
The effect of Reynolds number and grid resolution is investigated in this study. A series of numerical simulations are carried out for wide range of Reynolds number using coarse and fine grid system. The role of diffusion and the effect of grid resolution are clearly understood in the aspect of detonation structures and stabilities in the present study. It is considered that the numerical damping increase the mixing and combustion leading to the completion of combustion. Therefore it is recommended to introduce some sort of mathematical modeling that can account for the physical process of turbulence mixing and combustion in the highly unstable detonation structures.