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- 주제어 : Adjoint 변수 기법(Adjoint variable method) (검색결과 4 건)
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와류 발생 장치와 매개 변수 기법을 이용한 항공기 최적 설계
이준석,김은사,김종암 한국항공우주학회 2013 한국항공우주학회 학술발표회 논문집 Vol.2013 No.11
본 연구에서는 유동 박리와 실속 현상을 억제하는 와류 발생 장치를 이용하여, 항공기 동체-날개 연결 부분에서 발생하는 junction vortex를 제거하고자 하였다. 항공기 날개 윗면과 동체에 와류 발생 장치를 설치하였으며, 파라메트릭 스터디를 바탕으로 와류 발생 장치의 형상과 위치에 대한 최적 설계를 수행하였다. 특히 와류 발생 장치를 독립적으로 고려하여 디자인을 통한 유동 특성의 향상 효과를 극대화하고자 하였으며, 매개 변수 기법을 이용한 기울기 기반의 최적 설계 기법을 적용하여 15개의 많은 변수를 다룰 수 있도록 하였다. 최적 설계 결과, 항공기의 양항비가 5% 이상 증가하였고 junction vortex의 크기 및 세기 또한 감소하였다. To eliminate detrimental phenomena of junction vortex, this study dealt with an installation of the vortex generator on the wing surface and the body surface. A design optimization of vortex generator was also conducted by using results of the parametric study for the position of the vortex generator as a baseline. Because this design needed many design variables to consider each vortex generator individually, adjoint based sensitivity analysis for the gradient based design optimization was adopted. As a result, lift-to-drag ratio of the target aircraft was increased over 5%, and the junction vortex was also weakened.
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Kriging 기반 모델과 매개변수(Adjoint Variable)법을 이용한 항공기형상의 2단계 공력최적설계
임진우(J.W. Yim),이병준(B.J. Lee),김종암(C. Kim) 한국전산유체공학회 2009 한국전산유체공학회 학술대회논문집 Vol.2009 No.4
An efficient and high-fidelity design approach for wing-body shape optimization is presented. Depending on the size of design space and the number of design of variable, aerodynamic shape optimization process is carried out via different optimization strategies at each design stage. In the first stage, global optimization techniques are applied to planform design with a few geometric design variables. In the second stage, local optimization techniques are used for wing surface design with a lot of design variables to maintain a sufficient design space with a high DOF (Degree of Freedom) geometric change. For global optimization, Kriging method in conjunction with Genetic Algorithm (GA) is used. Asearching algorithm of EI (Expected Improvement) points is introduced to enhance the quality of global optimization for the wing-planform design. For local optimization, a discrete adjoint method is adopted. By the successive combination of global and local optimization techniques, drag minimization is performed for a multi-body aircraft configuration while maintaining the baseline lift and the wing weight at the same time. Through the design process, performances of the test models are remarkably improved in comparison with the single stage design approach. The performance of the proposed design framework including wing planform design variables can be efficiently evaluated by the drag decomposition method, which can examine the improvement of various drag components, such as induced drag, wave drag, viscous drag and profile drag.
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고 정밀 항공우주 유동해석 및 설계를 위한 공력계산 툴
김종암(Chongam Kim) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
As the computing environment is rapidly improved, the interests of CFD are gradually focused on large-scale computation over complex geometry. Keeping pace with the trend, essential computational tools to obtain solutions of complex aerospace flow analysis and design problems are examined. An accurate and efficient flow analysis and design codes for large-scale aerospace problem are presented in this work. With regard to original numerical schemes for flow analysis, high-fidelity flux schemes such as RoeM, AUSMPW+ and higher order interpolation schemes such as MLP (Multi-dimensional Limiting Process) are presented. Concerning the grid representation method, a general-purpose basis code which can handle multi-block system and overset grid system simultaneously is constructed. In respect to design optimization, the importance of turbulent sensitivity is investigated. And design tools to predict highly turbulent flows and its sensitivity accurately by fully differentiating turbulent transport equations are presented. Especially, a new sensitivity analysis treatment and geometric representation method to resolve the basic flow characteristics are presented. Exploiting these tools, the capability of the proposed approach to handle complex aerospace simulation and design problems is tested by computing several flow analysis and design problems.
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항공기 Junction Vortex 제어를 위한 Vortex Generator 최적 설계 연구
이준석(J. Yi),김은사(E. Kim),김종암(C. Kim) 한국전산유체공학회 2013 한국전산유체공학회 학술대회논문집 Vol.2013 No.5
A vortex located in a junction of wing-body configuration decreases the overall performance and stability of an aircraft. To eliminate this detrimental phenomenon, this study dealt with an installation of the vortex generator on the wing surface and the body surface, and the parametric study for the position of the vortex generator was performed. By adopting the results of this parametric study, a design optimization of vortex generator was also conducted. Because this design included a large number of design variables to consider each vortex generator individually, adjoint based sensitivity analysis for the gradient based design optimization was adopted. As a result, the aerodynamic performance of the target aircraft was substantially over 5%, and the junction vortex was shrunk and weakened enough.
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