http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
변재윤,유진선,허진영,정가람,김규홍 한국항공우주학회 2014 한국항공우주학회 학술발표회 논문집 Vol.2014 No.11
아크히터의 운용 범위 확장을 위한 기초 연구를 수치적 방법을 통해 수행하였다. 기초 모델로 사용된 0.4MW 아크히터를 ARCFLO4 코드를 이용하여 실험값과 비교함으로써, 해석 코드를 검증하였다. 아크히터에 4종류의 챔버를 부착하고 추가 유량을 공급하였고, 성능 예측을 위해 각 챔버별로 추가 공급 유량에 따라 내부 유동을 해석하였다. 각 해석 케이스 별로 전압력과 전엔탈피를 비교하여, 적절한 챔버 형상을 선정하였다. A fundamental research to expand operational ranges of an arc heater is performed. The numerical code ARCFLO4 is validated by comparing the analytical results to experimental results of 0.4 MW arc heater, the base model of the study. In order to expand the operating conditions, plenum chamber is attached and bypass flow is supplied then the performance is predicted for each case depending of the bypass flow rate. Furthermore, the most appropriate shape of the plenum chamber is chosen by comparing the total pressure and total enthalpy.
150㎾ 아크히터 수치해석에서의 복사모델 개선 및 시편 주변의 유입류 분석
변재윤(J.Y. Byeon),한상훈(S.H. Han),김규홍(K.H. Kim) 한국전산유체공학회 2011 한국전산유체공학회 학술대회논문집 Vol.2011 No.5
In this study, numerical analysis was performed for 150㎾ arc heater and inflow around specimen was studied. Pressure, voltage, etc. were similar to experimental data, however efficiency was over estimated. In order to correct efficiency, swirl effect and modified radiative heat flux using configuration factor were considered. It was shown that Swirl had little effect on efficiency although radiative heat flux played an important role on decreasing the efficiency of arc heater. In addition, non-equilibrium analysis that plasma flows moves from an arc heater’s nozzle to a specimen were performed.
변재윤(J.Y. Byeon),박정호(J.H. Park),김규홍(K.H. Kim) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.5
Radiation modeling is very important for numerical analysis of arc heater that produces very high enthalpy flows. Existing radiation model of ARCFLO4 is used for infinitely long cylinder, has the assumption of constant temperature in the axial direction. However in the case of 150kW arc heater, the assumption is not appropriate since the length of constrictor is too short. Thus DOM(Discrete Ordinate Method) radiation model and P-l radiation model were developed. In this study, each radiation model was applied to ARCFLO4 and numerical analysis was performed to compare with existing radiation model.
고온 플라즈마 발생장치를 이용한 텅스텐의 삭마 실험 및 수치해석
노성준,변재윤,유진선,허진영,김규홍 한국항공우주학회 2013 한국항공우주학회 학술발표회 논문집 Vol.2013 No.4
텅스텐과 같은 내열금속 재료는 고온 환경에서도 뛰어난 기계적 성질로 인하여 다양한 항공우주 분야의 내열성이 요구되는 분야에 사용되고 있으나, 공기중에서 산화 및 삭마에 취약하다는 단점이 있다. 이러한 단점을 개선하기 위한 기초연구로 텅스텐의 삭마/산화 거동을 알아보기 위해 플라즈마 발생장치를 이용하여 텅스텐 시편에 대한 삭마 실험을 수행하였으며, 텅스텐의 산화/삭마 속도 데이터를 확보하였다. 이를 수치적인 모델링을 통한 전산해석 결과와 비교하였으며, 수치적 모델링에 사용된 텅스텐의 산화반응속도 함수를 추론하였다. Recently, a high-wing aircraft is considered as one of the options to install high bypass ratio engines which improve fuel consumption of engines dramatically. However, when the wing is installed over the fuselage, there is possibility of the aerodynamic performance tends drop due to the interference effect between wing and fuselage. In order to prevent it, a fairing is required at the wing-fuselage junction. The purpose of this study is to optimize the wing and fairing configuration for high-wing aircraft to improve aerodynamic performance by using computational fluid dynamics simulation and optimization methods. As a result of the optimization, the optimized configuration achieved L/D of 19.75 with the reduction of shock wave. The optimized configuration suggests the wing performance is still important, although the fairing has certain influence.
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.