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초음속 유동장에서 기저 유동의 Detached Eddy Simulation
신재렬(J.R. Shin),원수희(S.H. Won),최정열(J.Y. Choi) 한국전산유체공학회 2008 한국전산유체공학회 학술대회논문집 Vol.2008 No.-
Detached Eddy Simulation (DES) is applied to an axisymmetric base flow at supersonic mainstream. DES is a hybrid approach to modeling turbulence that combines the best features of the Reynolds-averaged Navier-Stokes (RANS) and large-eddy simulation (LES) approaches. In the Reynolds-averaged mode, the model is currently based on either the Spalart-Allmaras (S-A) turbulence model. In the large eddy simulation mode, it is based on the Smagorinski subgrid scale model. Accurate predictions of the base flowfield and base pressure are successfully achieved by using the DES methodology with less computational cost than that of pure LES and monotone integrated large-eddy simulation (MILES) approaches. The DES accurately resolves the physics of unsteady turbulent motions, such as shear layer rollup, large-eddy motions in the downstream region, small-eddy motions inside the recirculating region. Comparison of the results shows that it is necessary to resolve approaching boundary layers and free shear-layer velocity profiles from the base edge correctly for the accurate prediction of base flows. The consideration of an empirical constant CDES for a compressible flow analysis may suggest that the optimal value of empirical constant CDES may be larger in the flows with strong compressibility than in incompressible flows.
신재렬(Jae-Ryul Shin),원수희(Su-Hee Won),최정열(Jeong-Yeol Choi) 한국추진공학회 2008 한국추진공학회 학술대회논문집 Vol.2008 No.5
본 연구의 목적은 수소 및 탄화수소를 이용한 bluff-body 화염 안정화 및 hyper-mixer와 같은 초음속 연소기 연료 분사기 주변의 유동해석 이다. 대규모 박리영역을 갖는 후방단 형상의 초음속 주변 유동을 해석하기 위한 검증 단계로 다양한 수치기법을 평가해 보았다. 고차 공간 정확도로 확장된 5차 TVD-MUSCL기법, Roe FDS, S-A DES/DDES 조합이 기저유동과 기저유출 유동에 좋은 결과를 보여 주었다. The purpose of this study is analysis of flow field where is around of injector of supersonic combustor which is bluff-body stabilized flame and hyper-mixer type of supersonic combustor injector by using hydrogen or hydrocarbon fuel. Various schemes are evaluated to supersonic backward step flow filed with massive separation region in validation step. Compounded scheme of 5th-order TVD-MUSCL, Roe FDS, S-A DES/DDES has a good performance in base and base-bleed flow.
신재렬(Jae-Ryul Shin),이대성(Dae-Sung Lee),오세종(Se-Jong Oh),최정열(J.-Y. Choi) 한국항공우주학회 2008 韓國航空宇宙學會誌 Vol.36 No.9
하이드라진(N₂H₄) 아크젯 추력기의 열화학 유동장 해석을 위한 전산유체해석을 수행하였다. 열복사와 전기장이 고려된 압축성 유동해석을 위해서 RANS 방정식을 수정하여 사용하였다. 로렌츠 힘과 Ohm 가열효과를 고려한 Maxwell 방정식이 유동방정식과 결합되어 전기 방전으로 인한 전기장해석을 위해 이용되었다. 아크젯 추력기 내부에서 유동장은 충분히 고온상태이기에 화학평형 해석이 이용되었으며, 광학 두께를 이용한 열복사 모델이 유동방정식에 적용되었다. 계산 결과들은 아크젯 추력기유동이 동결유동에 비해 추력은 180%증가되며, 비추력은 200%가까이 상승됨을 보여준다. 또한 유동장 해석 결과들은 아크젯 추력기 내부의 열적 물리적 특성에 대한 이해를 돕는다. The computational fluid dynamic analysis has been conducted for the thermo-chemical flow field in an arcjet thruster with mono-propellant Hydrazine (N₂H₄) as a working fluid. The Reynolds Averaged Navier-Stokes (RANS) equations are modified to analyze compressible flows with the thermal radiation and electric field. the Maxwell equation, which is loosely coupled with the fluid dynamic equations through the Ohm heating and Lorentz forces, is adopted to analyze the electric field induced by the electric arc. The chemical reactions of Hydrazine were assumed to be infinitely fast due to the high temperature field inside the arcjet thruster. The chemical and the thermal radiation models for the nitrogen-hydrogen mixture and optical thick media respectively, were incorporated with the fluid dynamic equations. The results show that performance indices of the arcjet thruster with 1㎾ arc heating are improved by amount of 180% in thrust and 200% in specific impulse more than frozen flow. In addition thermo-physical process inside the arcjet thruster is understood from the flow field results.
신재렬(Jaeryul Shin),정황희(Hwanghui Jeong),채종원(Jongwon Chae),이복직(Bokjik Lee) 한국연소학회 2023 KOSCOSYMPOSIUM논문집 Vol.2023 No.11
In this study, we proposed the MMH/NTO reduction mechanism to understand the hypergolic flow phenomenon of the bi-propellant. And the ignition delay was compared with the results of previous researchers. The result of one-dimensional numerical analysis show good agreement with the experimental and calculation results of one-dimensional numerical analysis show good agreement with the experimental and calculation results of previous researcher. Additionally, we perform a two-dimensional thermal flow calculation of the gas phase and the results are described here.
신재렬(J.R. Shin),김한영(H.Y. Kim),김대영(D.Y. Kim) 한국전산유체공학회 2011 한국전산유체공학회 학술대회논문집 Vol.2011 No.11
This study is performance estimation of wind augmentation device for BiWP(Building-integrated Wind Power) which recently attracts attention as a local power. various structures are installed on a rooftop of residential complex buildings and other high rise apartment buildings. Changing a profile of these, we designed a configuration that is able to capture much air and increase exit velocity. To estimate wind augmented effect of this device, we compared numerical analysis results with wind tunnel test results. Results show that exit velocity is increased from 24% to 60% by wind augmented device on a rooftop of building and uniform velocity profile is got for comparison without concerning wind augmentation.
추진기관시험설비에서 비반응 플룸모델을 이용한 한국형발사체 1단 추진기관의 배기플룸 거동 평가
신재렬(Jae-Ryul Shin),문성목(Seong-Mok Moon),김성룡(Seong-Lyong Kim) 한국추진공학회 2014 한국추진공학회 학술대회논문집 Vol.2014 No.12
추진기관의 개발 및 인증을 위한 시험설비 구조물에 대한 화염냉각 시스템 설계 및 평가를 위해 추진기관의 배기 플룸 해석을 수행하였다. 본 연구에는 상용 CFD 소프트웨어인 Fluent 13이 사용하고 배기 플룸은 단일 화학종 비반응 플룸 모델을 사용하여 수행하였다. 이 플룸 모델을 적용한 75톤 엔진의 성능 평가로부터 실무에 쉽게 적용가능하고 CEA 및 한국항공우주연구원의 제원 성능과 매우 잘 일치하는 결과를 보여주었다. 시험설비의 해석결과 화염유도로와 core 분사기가 고온의 픞룸 유동에 취약한 부분으로 평가 되었다. The exhaust plume analysis of propulsion system was carried out on the test facility structure for the design and evaluation of flame cooling system, this facility is for development and certification of a propulsion system. In this study, the commercial CFD software Fluent 13 is used and the exhaust plume was carried out using a single-species non-reacting plume model. From performance evaluation of the 75 tons engine, it is easily to apply in practice and the results show very good agreement with the performance specifications of KARI and the CEA. The results from analysis of the test facility, the core injectors and the flame deflector are weakness areas by high temperature plume flow.