• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.8
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• pp.693-698
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• 2007

A numerical method for accurate simulations of rotor aerodynamics is proposed. The numerical diffusion in the typically coarse grids away from the rotor blades is improved by implying a fourth-order of interpolation of local characteristic variables of the flow in the reconstruction stage of MUSCL approach in the framework of a finite volume formulation. In addition, different slope limiters are applied to the different characteristic fields, such as compressive limiters to linear characteristic fields to reduce the numerical dissipation whereas, diffusive limiters to nonlinear characteristic fields to increase numerical stability. Various exemplary problems related to the rotor aerodynamics applications are tested and the numerical results show a significant improvement in wake capturing capability. However, rotor aeroacoustic calculations show no meaningful difference over traditional MUSCL approach.

• Journal of the KSME
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• v.29 no.3
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• pp.306-316
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• 1989

최근 자동차 업계의 CAE 방향을 하드웨어 측면에서 보면, 대용량의 계산능력을 갖춘 슈퍼 컴 퓨터와 자체 계산능력을 갖춘 워크스테이션의 활용이 점차적으로 확대 되어가고 있다. 이것을 배경으로 크래쉬 시뮬레이션, 자동차 전체 시스템의 진동 및 소음해석, 공기역학적 특성을 고 려한 형상 최적화 등이 행해지고 있다. 이와 같은 해석을 원활히 수행하기 위해서 고려되어야 할 사항은 우선 사용 소프트웨어 상호간의 데이터 인터페이스를 충분히 고려한 체계적인 총합 CAE 시스템의 구축이고, 인공지능(artificial intelligence) 언어를 이용하여 사용이 용이한 해석 경 험(knowhow)의 데이터 베이스를 구축하는 것도 바람직하다. 또한 상용 소프트웨어가 지원하지 못하는 분야에 대한 자체 프로그램의 개발도 필요한 것이다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1994.05a
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• pp.28-38
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• 1994

분류층 가스화기 설계를 위한 일차연구로서 가스화기 이차공기 주입방법에 따른 비반응 난류장에 대한 수치해석을 검사체적에 기초한 유한차분방법을 이용하여 수행하였다. 압력과 속도의 연계문제는 SIMPLEC 알고리즘을, 레이놀즈 전단력은 k-$\varepsilon$ 난류모델을 사용하였다. 입자궤적 계산은 공기역학적 항력만을 고려하였으며 비선형적인 공기저항력에 의한 난류변동상관모델은 고려치 않았다. 이차공기 주입방법(parallel injection과 nonparallel 3$0^{\circ}C$ injection)에 따른 수치해석을 수행하여 Ar tracer의 질량분율에 대한 실험자료와 비교하여 만족할 만한 결과를 얻었으며 이차공기의 주입각 및 기타 제반변수에 따른 유동장 변화를 분석하였다.

• Aerospace Engineering and Technology
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• v.12 no.2
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• pp.180-185
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• 2013

In this study, preliminary design of human powered aircraft was performed by considering the aerodynamic performance. For this, overall weight including the aircraft and pilot was determined. Then, the main wing and horizontal/vertical tail were designed with appropriate selection of the airfoils and planform shapes. Based on these, three dimensional flow was calculated to obtain lift and drag coefficients and the position of center of gravity (CG). Consequently, it was shown that the lift and power of the aircraft satisfied the constraints of the minimum required lift and the pilot's available power. Also, the CG of the aircraft was located at aerodynamic center (AC) of the main wing, which guaranteed 26% of the static margin.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.6
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• pp.496-502
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• 2018

In this study, experimental and analytical studies were carried out to observe the phenomenon of aerodynamic throat formed according to the primary flow and secondary flow momentum of the ejector. The equilibrium interval of the aerodynamic throat, which is the main variable of the ejector performance, was observed through the experiment using the cold flow experiment and the analysis using FLUENT. Performance characteristics were investigated by the change of the primary flow rate and the throat diameter of the ejector cylinder. As a result, the performance of the standard ejector was confirmed to be within the range of 0.33~1.167(off-design/design) and cylinder throat diameter range of 1~1.17(off-design/design area ratio).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.759-760
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• 2008

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.371-375
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• 2006

A computational work has been performed to investigate the aerodynamics of a projectile which is launched from a ballistic range. A moving coordinate method for a multi-domain technique is employed to simulate unsteady projectile flows with a moving boundary. The variation of a virtual mass and the shape of projectile are added to the axisymmetric unsteady Euler equation systems. The present computational results properly predict the velocity, acceleration, drag histories and the major flow characteristics of the projectile.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.8
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• pp.877-884
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• 2006

The objective of this study is to investigate the aerodynamic characteristics of a vertical axis wind turbine blade as the basic study of a design of a vertical axis wind turbine. The lift and drag coefficients of the various shape of the vortical axis wind turbine blades are analyzed and compared using the CFD code Fluent. To validate the numerical analysis, the predicted results of the Fluent are compared with those of the Xfoil code and the experimental results. We conclude that the program Fluent can be used to predict the aerodynamics of the wind turbine blade. By comparing the predicted results of the aerodynamic characteristics of the different shape of the blades, an appropriate shape of the blade is suggested to design the vortical axis wind turbine blade.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.12
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• pp.1273-1283
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• 2011

A 3-dimensional unsteady numerical analysis has been performed to evaluate the aerodynamic characteristics of a Giromill. Generally, the structure of a Giromill is simple and therefore easy to develop. In addition, the high solidity of the Gironmill helps improve the self-starting capacity at a low tip speed ratio (TSR). However, contrary to the Darrieus wind turbine which has a TSR of 4-7, a Giromill has a low TSR of 1-3. In this study, the aerodynamic characteristics of the Giromill are investigated using computational fluid dynamics (CFD). Three straight-bladed wings are used, and the solidity of the Giromill is 0.75. In contrast to a Darrieus wind turbine having low solidity, the Giromill shows a sudden decrease in the aerodynamic performance because of the interference between the wings and an increase in the drag on the wings in the downstream direction where wind flow is significantly reduced. Consequently, the aerodynamic performance decreased at a TSR value lower than 2.4.

• Proceeding of EDISON Challenge
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• 2016.11a
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• pp.1-3
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• 2016

대형 화물 트럭(heavy-duty truck)은 화물 적재에 용이하지만, 공기역학적으로 불리한 형상을 가진다. 이러한 단점을 극복하고자 대형 화물 트럭에는 공기저항력(aerodynamic drag)을 줄일 수 있는 여러 가지 장치가 달려있다. 본 논문에서는 디플렉터(deflector) 형상이 항력 감소에 어떠한 영향을 주며, 평판 형태와 굴곡진 형태의 디플렉터 형상에 대한 항력 계수 비교를 EDISON-CFD를 활용하여 비교하였다. 해석 결과, 측풍(side-wind)의 영향을 무시하며 차량 속도 95 km/h로 등속을 유지하는 조건에서 평판 형태의 Model 1과 바깥으로 굴곡진 Model 2에서 전체 항력 계수가 낮게 나타났다.