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환형 관내를 전파하는 데토네이션 파의 파면 구조 및 안정성
이수한(Lee S.-H.),조덕래(Cho D.-R.),노진현(Noh J.-H.),최정열(Choi J.-Y.) 한국연소학회 2008 KOSCOSYMPOSIUM논문집 Vol.- No.-
Pre 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.
TBCC를 위한 CVC 엔진의 데토네이션 현상 기초 연구
최정열(J.-Y. Choi),Bernard Parent,조덕래(D.-R. Cho),강기하(K. Kang),신재렬(J.-R. Shin),이수한(S.-H. Lee),이태형(T.-H. Yi) 한국추진공학회 2008 한국추진공학회 학술대회논문집 Vol.2008 No.11
DARPA가 계획 중인 대형 극초음속 추진 기관 개발 프로그램 VULCAN 프로그램은 듀얼모드 램제트/스크램제트 엔진과 연계되어 TBCC엔진을 이룰 수 있도록, 기존의 터보제트(또는 터보팬) 엔진과 CVC과 엔진을 결합하여 마하수 4이상에서 작동 가능한 엔진을 개발하는 것을 목표로 하고 있다. CVC 엔진은 데토네이션 연소 현상을 기본으로 하여 고마하수에서 고효율을 얻을 수 있는 PDE 이나 CDE와 같은 신개념의 엔진이다. 본 논문에서는 부산대학교 항공우주공학과 연소 추진 연구실에서 지난 수년간 국제공동 연구의 형태로 수행한 데토네이션 현상의 추진기관 응용에 연구에 대하여 소개한다. DARPA"s hypersonic propulsion program VULCAN is aimed for development of Mach 4+ capable engine by combining current production turbofan engine such as F119 with CVC (Constant Volume Combustion) engine. Final goal is a TBCC(Turbo-based Combined Cycle) engine by combining with dual mode ramjet/scramjet engine. CVC is a common designation of new concept of high efficiency engines, such as Pulse Detonation Engine (PDE) or Continuous Detonation Engine (CDE), which use the detonation as a combustion mechanism. Present paper introduces the internationally collaborative research activities carried out in Aerospace Combustion and Propulsion Laboratory of the department of Aerospace Engineering of the Pusan national University.
INSTABILITY OF OBLIQUE SHOCK WAVES WITH HEAT ADDITION
J.Y. Choi(최정열),J-R. Shin(신재렬),D.R. Cho(조덕래) 한국전산유체공학회 2007 한국전산유체공학회 학술대회논문집 Vol.2007 No.-
A comprehensive numerical study was carried out to identify the on-set condition of the cell structures of oblique detonation waves (ODWs). Mach 7 incoming flow was considered with all other flow variables were fixed except the flow turning angles varying from 35 to 38. For a given flow conditions theoretical maximum turning angle is 38.2° where the oblique detonation wave may be stabilized. The effects of grid resolution were tested using grids from 255×100 to 4,005×1,600. The numerical smoked foil records exhibits the detonation cell structures with dual triple points running opposite directions for the 36 to 38 turning angles. As the turning angle get closer to the maximum angle the cell structures gets finer and the oscillatory behavior of the primary triple point was observed. The thermal occlusion behind the oblique detonation wave was observed for the 38° turning angle.
멀티코어 시스템에서 쓰레드 수에 따른 CFD 코드의 OpenMP 병렬 성능
김종관(J.-K. Kim),장근진(K.-J. Jang),김태영(T.Y. Kim),조덕래(D.-R Cho),김성돈(S.-D. Kim),최정열(J.-Y. Choi) 한국전산유체공학회 2013 한국전산유체공학회지 Vol.18 No.1
OpenMP is becoming more and more useful as a simple parallel processing paradigm on SMP (Shared Memory Multi-Processors) computing environment with the development of multi-core processors. However, very few data is available publically regarding the OpenMP performance in CFD (Computational Fluid Dynamics). In the present study a CFD test suite is prepared for the performance evaluation of OpenMP on various multi-core systems. The test suite is composed of two-dimensional numerical simulations for inviscid/viscous and reacting/non-reacting flows using three different levels of grid systems. One to five test runs were carried out on various systems from dual-core dual threads to 16-core 32-threads systems by changing the number of threads engaged for each test up to 80. The results exhibit some interesting results and the lessons learned from the tests would be quite helpful for the further use of OpenMP for CFD studies using multi-core processor systems.
KARI 30톤급 액체 로켓 엔진 노즐 유동 화학 평형 해석
이대성(Dae-Sung Lee),강기하(Ki-Ha Kang),조덕래(D. -R. Cho),최정열(Jeong-Yeol Choi),최환석(H. -S. Choi) 한국추진공학회 2008 한국추진공학회지 Vol.12 No.3
Nozzle flow analyses of 30 ton<SUB>f</SUB>-class KARI liquid rocket engine for high altitude propulsion are carried out using a chemically frozen and equilibrium flow analysis code developed previously. It is considered that the combined frozen- and shifting- equilibrium analysis is cost-effective regarding the convergence characteristics and modeling uncertainties, though the non-equilibrium analysis is most reliable approach. A dependable performance prediction could be attainable through the present analyses that account for the recombination process and thermal and kinetic energy recovery during the expansion process with viscous effects.