• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.152-161
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• 2009

This thesis aims to report the result of an evaluation of the aerodynamic characteristic on the purchase conditional pantograph model that has developed for applying to the KTX-I. Development pantograph was derived the result of aerodynamic characteristic through a wind tunnel test. And design modification was proceeded to solve the difference of aerodynamic characteristic by pantograph's operating direction. The verification test and adjustment test about the modified pantograph's aerodynamic characteristic were progressed on the KTX-I. To be corresponded with requirements, the airfoil and spoiler were used.

• Journal of Mechanical Science and Technology
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• 제14권12호
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• pp.1358-1364
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• 2000

• EDISON SW 활용 경진대회 논문집
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• 제5회(2016년)
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• pp.632-637
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• 2016

This study shows what difference would be made to the aerodynamic characteristic with different thickness ratio of the same airfoil, Eppler 387, at low Reynolds number, at the angle of attack of $0^{\circ}$. Konkuk Univ.'s airfoil has a bigger thickness ratio than that of the original Eppler 387 airfoil. The reason for the thicker camber is a Pt 100 ohm heater mounted inside the Konkuk Univ.'s airfoil and this was assumed to make some differences to aerodynamic characteristic. The comparison of these two airfoils' CFD data, provided by EDSION_CFD, with real experiment that had been made in subsonic wind tunnel at Konkuk Univ. is done. A finer result would come out if the complement of the homogeneity of the wind tunnel's fluid is done in the future.

• 한국추진공학회지
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• 제3권3호
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• pp.40-46
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• 1999

풍력발전용 회전날개의 공력성능과 시동특성은 정격출력 및 운용방법 등의 전체적인 시스템 성능을 결정짓는 중요한 요소이다. 따라서, 풍력발전용 회전날개를 설계한 경우 공력성능과 풍속 및 깃각에 따른 시동특성은 반드시 검토되어야 한다. 이를 위해 본 연구에서는 수평축 풍력발전용으로 개발된 회전날개의 공력성능을 해석하기 위한 프로그램을 개발하였으며, 타당성 검증을 위해 상용화 되어있는 회전날개의 공력성능해석을 수행한 결과 회사측에서 제시한 실험치와 잘 일치함을 확인하였다. 또한 개발된 공력 해석 프로그램을 바탕으로 시동특성 해석 프로그램을 개발하여 분석한 결과 우리나라와 같이 저풍속에서 운용되는 풍력발전기에는 가변깃각 제어방식이 유리함을 확인하였다.

• 한국항공우주학회지
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• 제40권2호
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• pp.139-145
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• 2012

천음속 영역에 적합하도록 개발된 수정 Sonic Arc 익형의 저속 공력특성에 대해 조사하였다. 이 익형은 Schwendenman이 제안한 sonic arc 형상 함수와 NACA0012 형상 data 그리고 상용 프로그램 Maple을 이용하여 설계하였다. 수정 Sonic Arc 익형의 저속공력 특성을 조사하기 위해 마하수 0.3 이하에서 수치해석을 수행하고 그 결과를 NACA0012 익형의 저속 공력성능과 비교분석하였다. 각 마하수에서 수정 sonic arc 익형의 항력은 NACA0012의 항력보다 약 1.5% 정도 작게 나타났으며, 양력 비교에서도 수정 Sonic Arc 익형의 양력은 NACA0012의 양력보다 약 2% 정도 일정하게 작게 나타났다. 또한 각 마하수에서 수정 Sonic Arc 익형의 모멘트 계수는 NACA0012의 값보다 약 1.4% 정도 작게 나타났다.

• Wind and Structures
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• 제26권6호
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• pp.355-367
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• 2018

This paper studies the aerodynamic stability of a tensioned, geometrically nonlinear orthotropic membrane structure with hyperbolic paraboloid in sag direction. Considering flow separation, the wind field around membrane structure is simulated as the superposition of a uniform flow and a continuous vortex layer. By the potential flow theory in fluid mechanics and the thin airfoil theory in aerodynamics, aerodynamic pressure acting on membrane surface can be determined. And based on the large amplitude theory of membrane and D'Alembert's principle, interaction governing equations of wind-structure are established. Then, under the circumstance of single-mode response, the Bubnov-Galerkin approximate method is applied to transform the complicated interaction governing equations into a system of second-order nonlinear differential equation with constant coefficients. Through judging the frequency characteristic of the system characteristic equation, the critical velocity of divergence instability is determined. Different parameter analysis shows that the orthotropy, geometrical nonlinearity and scantling of structure is significant for preventing destructive aerodynamic instability in membrane structures. Compared to the model without considering flow separation, it's basically consistent about the divergence instability regularities in the flow separation model.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2004년도 추계 학술대회논문집
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• pp.177-180
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• 2004

The development of a tilting train with construction of electric line on the conventional railway is required for speed-up on the conventional railway with many curving sections. For development of tilting train, the study and development of the tilting system and tilting bogie having the different mechanism with a general high speed train will play a main role for improving the technology in the field of Korean railway The study and development of the pantograph tilting mechanism in order to keep a good contact behavior between a pantograph and a contact wire by tilting a pantograph on the opposite direction of the vehicle tilting direction. In this study, we analyzed the aerodynamic characteristic of a developing pantograph on the tilting train and obtained the contact force with catenary by aerodynamic lift force by the aerodynamic analysis. We also performed the numerical analysis for design the device controlling lift force on a pantograph. From the aerodynamic simulation and parameter study for a device to control the lift force, we will suggest the various shape and the optimal shape of it corresponding to a developing tilting pantograph. The Fluent software is used for the calculation of flow profile in this study.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.467-471
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• 2004

The development of a tilting train with construction of electric line on the conventional railway is required for speed-up on the conventional railway with many curving sections. For development of tilting train, the study and development of the tilting system and tilting bogie having the different mechanism with a general high speed train will play a main role for improving the technology in the field of Korean railway. The study and development of the pantograph tilting mechanism in order to keep a good contact behavior between a pantograph and a contact wire by tilting a pantograph on the opposite direction of the vehicle tilting direction. In this study, we analyzed the aerodynamic characteristic of a developing pantograph on the tilting train and obtained the contact force with catenary by aerodynamic lift force by the aerodynamic analysis. We also performed the numerical analysis for design the device controlling lift force on a pantograph. From the aerodynamic simulation and parameter study for a device to control the lift force, we will suggest the various shape and the optimal shape of it corresponding to a developing tilting pantograph. The Fluent software is used for the calculation of flow profile in this study.

• 한국항공우주학회지
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• 제33권6호
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• pp.21-30
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• 2005

헬리콥터 로터 블레이드 예비설계 단계에서 에어포일 선정과 분포의 기초 자료를 생성하기 위해 로터 에어포일 공력해석을 수행하였다.기존 헬리콥터의 에어포일 중 공력해석 대상으로 10개를 선정하고 블레이드 요소이론을 이용한 공력해석에 적합한 table 형태의 공력계수 자료를 생성하였다. 해석 비용을 고려, 풍동시험 대신 간단한 수학적 모델을 이용하여 모든 받음각 영역($-180^{o}\sim180^{o}$)에서 공력특성 곡선($C_{l},C_{m},C_{d}$)을 구성하였다. 공력특성곡선 구성에 필요한 각 에어포일의 필수 공력자료를 IBLM을 이용하여 구하였으며, 구성된 공력특성곡선은 실험결과와 정성적으로 일치하였다. 마지막으로, 에어포일 선정과 분포설계의 기준을 마련하기 위하여 각 에어포일의 양력계수, 모멘트계수를 상호 비교한 후 분류하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.561-564
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• 2002

For the reduction of fuel consumption of high speed, the aerodynamic drag must be reduced. In early vehicle design process, it is very important to have information about aerodynamic characteristics of design models. In this phase CFD methods are usually used to predict the aerodynamic forces. But commercial programs using turbulence models cannot give a good agreement with experimental result and have also problems with convergence. PowerFLOW employs a new technology called DIGITAL PHYSICS, which provides a different approach to simulating fluids. DIGITAL PHYSICS uses a lattice-based approach (extended from lattice-gas and lattice-Boltzmann methods) where time, space and velocity are discrete. This discrete system represents the Wavier-Stokes continuum behavior without the numerical instability Issues of traditional CFD solvers, such as convergence. In this paper, aerodynamic performance of vehicles are simulated using PowerFLOW by Exa and results are compared with experimental wind tunnel data.