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한상훈(S.H. Han),변재윤(J.Y. Byeon),김규홍(K.H. Kim) 한국전산유체공학회 2010 한국전산유체공학회 학술대회논문집 Vol.2010 No.5
Numerical analysis of 150kW Huels-type arc jet was performed using compressible Navier-Stokes CFD code. To consider chemical reaction by high temperature, the flow was assumed to be chemical equilibrium states. As a turbulence and a radiation model, the two-equation k-epsilon model and the 3-band radiation model were adopted, respectively. Mass flow rate and current density were given as conditions for calculations. In this study, two kinds of mechanisms for injection of air flow wire considered. One is that air is provided by left wall surface and the other is that air is injected from upper wall surface. The pressure, density and temperature contours of two cases were compared and heat transfer rates were estimated. The numerical results of two cases were not much different to each other. However, in real 150KW device, air is injected from upper wall surface with swirl. To calculate more accurately, swirl effect is must be considered.
김재관(J. G. Kim),이준우(J. W. Lee),김규홍(K. H. Kim) 한국전산유체공학회 2010 한국전산유체공학회 학술대회논문집 Vol.2010 No.5
Numerical investigation was conducted to study the effects of after-body configurations and nozzle lip on the PIFS(Plume Induced Flow Separation) and heat flux to the base face. Two dimensional and axi-symmetric non-equilibrium Navier-Stokes solver with k-ω SST turbulence model was used to solve the launching vehicle type configuration with propulsive jet. The experimental result of Robert J. McGhee was compared with our computational results for code validation. Three types of the after-body configurations (Straight, Boat-tail, Flare type) were simulated for this study. And the nozzle lip effect was studies using the three types of base configurations with same simulation conditions. As a result of numerical investigations, higher pressure ratio condition and boat-tail after-body configuration caused severe PIFS phenomenon but the flare type after-body configuration and low pressure ratio suppressed PIFS. Flare type after-body configuration and low pressure ratio case reduced heat flux to base face. The nozzle lip dispersed the heat flux widely along the base face and the nozzle lip.
김재관(J.G. Kim),이준우(J.W. Lee),김규홍(K.H. Kim) 한국전산유체공학회 2011 한국전산유체공학회 학술대회논문집 Vol.2011 No.11
Numerical investigation was conducted to study the effects of after-body configurations and altitude conditions on the PIFS (Plume Induced Flow Separation) and heat flux to the base face. Two dimensional and axi-symmetric Navier-Stokes solver with k-w SST turbulence model was used to solve the various configuration with propulsive jet. The cylinder, boat-tail and flare after-body configurations and six different altitude conditions (5, 10, 20, 30, 40, 50Km) are used in this study. As a result of numerical investigations, higher pressure ratio condition and boat-tail after-body configuration caused severe PIFS phenomenon but the flare type after-body configuration suppressed PIFS. Flare type after-body configuration reduced heat flux to base face.
MLP 기법을 이용한 H<SUB>2</SUB>/CO/Air 초음속 동축 난류 화염 해석
최정열(J.-Y. Choi),김규홍(K.-H. Kim),한상훈(S.-H. Han) 한국전산유체공학회 2011 한국전산유체공학회 학술대회논문집 Vol.2011 No.11
A MLP(Multi-Dimensional Limiting Procedure) scheme is applied for a supersonic turbulent combustion flow field developed for the multi-dimensional high resolution analysis of compressible flow field. LES (Large Eddy Simulation) is dominantly used for the turbulent combustion studies in these days since the turbulent combustion is governed by fuel/air mixing controlled by small scale eddy motion in fuel/air mixing layer. Present study demonstrate the superiority and efficiency of MLP scheme in compared previous 3<SUP>rd</SUP> order MUSCL scheme and 5<SUP>th</SUP> order WENO scheme by applying MLP scheme to the hybrid RANS/LES study of supersonic turbulent combustion flow field where high resolution shock capturing scheme is essential.
김규홍(K.H. Kim),정가람(G. Jeong),채정헌(J.H. Chae) 한국전산유체공학회 2013 한국전산유체공학회 학술대회논문집 Vol.2013 No.5
Hypersonic vehicles experience high speed and high temperature flow environment. At the time, Shock-wave/boundary layer interaction can occur which leads to local peaks of heat transfer. Therefore ablation phenomenon can occur at the interaction region. To understand the ablation phenomenon by the interaction, numerical investigation is performed considering shock-wave on boundary layer of a flat plate consisting of carbon/carbon. The coupled scheme with thermochemical ablation model is used with the higher-order overset grid method to conveniently reflect changing shapes by ablation. By the numerical approach, ablation process at flat plate by Shock-wave/boundary layer interaction during 0.0s to 4.12 s is discussed.
전산해석을 이용한 실리카-페놀 열방어구조물의 용융을 포함한 삭마 현상 예측
김평기(P. K. Kim),노성준(S. J. Noh),김규홍(K. H. Kim),박경민 한국전산유체공학회 2014 한국전산유체공학회 학술대회논문집 Vol.2014 No.5
Ablation model for silica-phenolic Thermal Protection System(TPS) was developed in this study. Also, computational analysis for such TPS was conducted using the developed model. In order to analyze ablation phenomenon inside the solid, mass and energy balance equations were used as the governing equations. The total recession is modeled to be the sum of recession by reaction and melting. CFD analysis was conducted to predict the minimum radius of TPS for various flight Mach number which can protect the vehicle. This study can aid in preliminary designs of TPS since the minimum radius of TPS can be predicted.