오픈로터 소음 저감을 위한 비정상 유동 하의 강건최적설계

권형일(H. I. Kwon),최성임(S. Choi),권장혁(J. H. Kwon) 한국전산유체공학회 2014 한국전산유체공학회 학술대회논문집 Vol.2014 No.5

Robust design optimization for open rotor has been conducted. To alleviate computational burden of robust measurement in the design, Kriging surrogate model was employed to model responses. For performance evaluations of open rotor especially, unsteady flow simulation by state-of-the-art CFD technique of harmonic balance method was used, and it coupled with aeroacoustic analysis based on acoustic analogy. Thanks to the combined analysis between aerodynamic and aeroacoustic analyses, unsteady noise characteristics of the open rotor was efficiently investigated. The baseline configuration is 8×8 pusher-type of DLR CROR system, and rated condition is a cruise regime. Two types of aleatory uncertainties were modeled by probability density functions, and reflected in design variables and free-stream Mach number. The result showed that about 3dB of noise reduction was achieved, with it maintained thrust level of the baseline rotor system. Moreover, the validation of robustness for the uncertainties was performed, and showed the robust optimum rotor was more insensitive to the uncertainties than the baseline open rotor.

e-Science 기반 EDISON 포탈의 항공우주분야 에어포일 공력 최적 설계 프레임워크 개발

권형일(H.I. Kwon),조영민(Y.M. Jo),이슬기(S.G. Yi),김사지(S.J. Kim),최성임(S.I. Choi) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.5

Design optimization is to find optimum of design space which is defined by design variables, using optimization algorithm. Recently, numerical design optimization including computational fluid dynamics (CFD) has been focused in not only aerospace engineering, but general engineering field because of many research and development for high performance computing. However it could hardly find the design optimization softwares and contents of which educational or research purposes in aerospace engineering. In this study, as one framework of EDISON DESIGN OPTIMIZATION, aerodynamic design optimization framework for an airfoil based on EDISON (EDucation-research Integration through Simulation On the Net) portal. As well as the softwares development, essential contents are also developed for the lecture associated with design optimization in the aerospace engineering. Software and contents on aerodynamic design optimization could be expected to be assisted in the lecture or lab..

전기추진 항공기용 프로펠러의 다단 형상 최적 설계

권형일(H.I. Kwon),이슬기(S.G. Yi),최성임(S.I. Choi),김근배(K.B. Kim) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.11

In this study, we present that multi-stage design framework for aerodynamic design optimization of rotary wing such as propeller and helicopter rotor blades. Strategy of the proposed framework is to enhance aerodynamic performance using both planform and sectional design optimization iteratively. In first stage of planform design, we used genetic algorithm and blade element momentum theory(BEMT) based on two dimensional aerodynamic database to find optimal planform variables in short time. After initial design, local flow conditions of blade sections are calculated. Next stage, sectional design optimization is conducted using two dimensional Navier-Stokes analysis and gradient based optimization algorithm. Mien optimal shapes are determined, planform design is performed again. Through the iterative design process, not only optimal flow condition but also optimal shape could be acquired. To validate the framework, design optimization for propeller which operated in electric vehicle system were performed As a results, about 8% of efficiency enhancement has acquired.

e-Science 기반의 항공우주분야 교육·연구용 공력 최적 설계 프레임워크를 활용한 에어포일의 공력 최적 설계 연구

이학진(H.J. Lee),유민석(M.S. Ryu),권형일(H.I. Kwon),최성임(S.I. Choi) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.5

In this study, aerodynamic design optimization of airfoil was performed to minimize drag of baseline airfoil at transonic flow by using e-Science based design framework. Prior to the design optimization, parameter sensitivity studies were performed to determine the step-size and the sensitivity of the objective function. In this research, the weight of a Hicks-Henne bump function served as a design variable. Aerodynamic analysis was carried out by EDISON CFD Solver. An aerodynamic design optimization framework of airfoil selected a drag-minimized optimal configuration by using the gradient-based optimization algorithm. Design results showed that the drag and lift performances of an optimized airfoil have been improved by 95% and 7% respectively. In addition, the performance of an optimized airfoil was validated by performing the off-design study in different design flow conditions. Through this study, A aerodynamic design optimization framework of airfoil can be utilized as an educational & research aerodynamic design optimization resource.

유동 간섭 효과를 고려한 Wing-sails 공력 최적 설계

이학진(H.J. Lee),조영민(Y.M. Jo),권형일(H.I. Kwon),최성임(S.I. Choi) 한국전산유체공학회 2013 한국전산유체공학회 학술대회논문집 Vol.2013 No.5

These day, an issues related with environments are becoming more pressing. We investigated potential next-generation vessel which makes use of the wing-sails to support existing fossil fuel-based propulsion system. The sailing-ship is a new concept eco-friendly vessel that uses the wind energy to produce additional thrust force by wing-sails above the hull. In this study, we focused on the aerodynamic analysis and design optimization of multiple wing-sails by varying the wind direction 15 degrees to 165 degrees. For the numerical analysis, we solved three dimensional compressible Navier-stokes equation with Spalart-Allmaras turbulent model. After the investigation of aerodynamic characteristics around wing-sails and the effect of flow interactions, we performed the design optimization of wing-sails by considering both single wing-sail and multiple wing-sails. In single wing-sail design, we found optimal value of deflection angle and flap length of single wing-sail to maximize the lift performance. In multiple wing-sails design, we carried out design optimization to find an optimal set-up of individual for each of the wing-sails that maximize total thrust of wing-sails. These optimal set-up include a deflection angle, deflection length and angle of attack of each wing-sails. Using a Kriging-based surrogate model and the derivative-free optimization method of genetic algorithms (GAs), we found the optimal set-up of the single and multiple wing-sails. The design optimization results showed that the total thrust of wing-sails has improved by 27~36% corresponding to the varying the wind directions.

e-science 기반의 항공우주분야 교육·연구용 공력 최적 설계 프레임워크를 활용한 에어포일의 역설계 연구

김태희(T.H. Kim),권형일(H.I. Kwon),최성임(S.I. Choi) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.5

Recently, with advanced computational performance, numerical design optimization including CFD has been developed in aerospace engineering. However it could hardly find the design optimization softwares and contents of which educational purposes in aerospace engineering. In this study, inverse shape design is developed for steady, two dimensional inviscid and compressible flow over airfoils using aerodynamic design optimization framework for an airfoil based on EDISON_CFD(Education-research through Simulation On the Net for Computational Fluid Dynamics). Design optimization is performed for drag minimization in transonic flow. Two target pressure distributions are RAE2822 known as transonic airfoil and previously designed airfoil for drag minimized from NACA0012 airfoil. Both result showed that shape, lift coefficient, and drag coefficient of baseline airfoil got closer to those of target airfoil. From a result, contents of design optimization framework could be expected to help in the lecture.

공동 최적화 기법을 이용한 항공기 날개 설계

김태희(T.H. Kim),권형일(H.I. Kwon),최성임(S.I Choi) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.11

Collaborative optimization is a multi-level methodology for multidisciplinary optimization. The collaborative optimization does not require direct communication between each discipline and secures a disciplinary autonomy. But the collaborative optimization has problem at convergence of objective function and computational cost. In this paper, for better convergence, GA(Genetic Algorithm) is used as both system level optimizer and subspace level optimizer of the Collaborative optimization. In doing so, the performance of Collaborative Optimization is discussed by applying two example problems and aircraft wing design problem.

고효율 EAV 프로펠러의 다분야 최적설계

이슬기(S.G. Yi),권형일(H.I. Kwon),최성임(S.I. Choi),박부민(P.M. Park),강영석(Y.S. Kang) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.5

A multidisciplinary design optimization of EAV (Electric Aerial Vehicle) propeller is carried out to maximize the efficiency of propeller performance. An objective is to minimize torque/power while maintaining a thrust level of baseline configuration at a given RPM and thus to improve propeller efficiency. Structural safety is also calculated during the design process and is ensured to satisfy a safety margin. A high-fidelity CFD and FEM-based structures computation is employed for a design. To test the accuracy of the analysis tools, a wind-tunnel test is conducted for the baseline propeller blade at operating RPM and numerical prediction is validated against experiment data. A derivative-free multidisciplinary design methodology based on the Kriging approximation model is used to achieve the design goal of minimization of torque. Design variables are mostly related to the shape of the blade and include twist distribution at eight cross sections along the blade span as well as the planform shape of the blade around tip area. Design results demonstrate a reduction of torque by almost 5% at constant thrust. Safety margin is well satisfied for a new blade.