• Journal of Aerospace System Engineering
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• v.10 no.4
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• pp.11-16
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• 2016

In this paper, an experimental study on the aerodynamic characteristics of a variable span wing flying inside a channel guideway is accomplished using wind tunnel testing. A variable span wing with a NACA 0012 airfoil section was fabricated and actuated using a linear servo motor. The aerodynamic effects of 1) wing aspect ratio, 2) ground effect, and 3) the gap between the wingtip and the wing fence were investigated. It was found that both ground effect and wing fence gap increased lift. Also, the wing fence gap does not significantly affect drag. Therefore, it was found that a variable span mechanism can be used as an effective high lift device when flap use is limited.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.257-265
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• 2009

The present study deals with the leading edge shape on a wing-body junction to decrease a horseshoe vortex, one of the main factors to generate the secondary flow losses. The shape of leading-edge is optimized with design variables form the leading-edge shape. Approximate optimization design method is used for the optimization. The study is investigated using $FLUENT^{TM}$ and $iSIGHT^{TM}$. As the result, total pressure coefficient of the optimized design case was decreased about 9.79% compare to the baseline case.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.04a
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• pp.270-275
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• 1995

본 논문에서는 3자유도를 갖는 2차원 강체날개의 플러터 속도를 향상시키는 축차 제어기를 설계하는 기법을 연구하였다. 먼저 2차원 강체날개의 운동방정식을 유도하고 플러터 해석을 수행하였다. 다음 수동계의 플러터 속도를 향상시키는 능동제어기를 설계한 후 제어기의 차수를 축차하는 기법을 적용하여 저차의 능동제어기를 구성하였다. 제어기 축차기법으로는 BACR을 사용하였으며 전차 제어기의 상태변수를 약 80%정도 줄일 수 있다. 축차된 제어기를 사용한 능동시스템과 전차 제어기를 사용한 능동시스템의 제어효과의 차이는 무시 할 수 있을 정도로 매우 작다. 따라서, BACR을 사용하여 얻은 축차된 제어기를 사용하면 상당한 계산량 감소효과와 실시간 단축효과를 얻을 수 있음을 확인하였다. 또한 동일한 돌풍입력에 대한 각각의 능동 시스템의 시간응답도 매우 양호한 결과를 얻을 수 있었으며, 전차 제어기를 사용한 능동시스템의 돌풍응답과 축차된 제어기를 사용한 능동시스템의 돌풍 응답 사이의 차이도 매우 작게 나타났다. 그러므로, 항공기 날개의 능동 플러터억제에는 BACR을 이용하여 설계한 축차된 제어기가 플러터 능동제어에 매우 유용하다고 할 수 있다. 그러나 BACR을 사용하기 위해서는 요구되는 정확도와 계산량에 대한 상호 절충과정이 반드시 필요하다.

• Composites Research
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• v.13 no.2
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• pp.61-71
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• 2000

Today, the use of composite materials become an essential part in the design and manufacturing process of the flight vehicles to reduce the structural weight. Since the structural properties can be varied largely due to the stacking sequence of ply angles, it is very important problem to determine the optimized ply angles under a design objective. Thus, in this study, the analysis of static aeroelastic optimization of a composite wing has been performed. An analytical system to calculate and optimize tile aero-structural equilibrium position has been developed and incorporated with the genetic algorithm. The effects of stacking sequence on the structural deformation and aerodynamic distribution have been studied and calculated with the condition of minimum structural deformation for a swept-back composite wing. For the set of practical stacking angles, the design results to maximize the performance of static aeroelasticity are also presented.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.10
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• pp.984-991
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• 2009

In this study, transonic aeroelastic response analyses have been conducted for the DLR-F4(wing-body) aircraft configuration considering shockwave and flow separation effects. The developed fluid-structure coupled analysis system is applied for aeroelastic computations combining computational structural dynamics(CSD), finite element method(FEM) and computational fluid dynamics(CFD) in the time domain. It can give very accurate and useful engineering data on the structural dynamic design of advanced flight vehicles. For the nonlinear unsteady aerodynamics in high transonic flow region, Navier-Stokes equations using the structured grid system have been applied to wing-body configurations. In transonic flight region, the characteristics of static and dynamic aeroelastic responses have been investigated for a typical wing-body configuration model. Also, it is typically shown that the current computation approach can yield realistic and practical results for aircraft design and test engineers.

• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.3
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• pp.40-46
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• 1999

Aerodynamic performance and starting characteristic of wind turbine blade are important factors that determine the whole system as rated power, operating method, etc. Therefore, starting characteristic according to aerodynamic performance, wind speed and blade pitch angle should be examined while wind turbine blade is designed. In this study, the aerodynamic analysis program of 750㎾ class horizontal axis wind turbine blade was developed and to certify this program, the aerodynamic performance of the commercialized blade was analyzed with it. The analysis result was corresponding to the value presented from manufacturer. And the starting analysis program was developed on the basis of the developed aerodynamic analysis program and starting analysis was performed. As a result, it was confirmed that variable speed operation and variable pitch control are profitable to wind turbine used in low wind speed as our country.

• Journal of the Korea Convergence Society
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• v.12 no.2
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• pp.215-219
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• 2021

The flow analyses around the wing of airplane installed with winglet or sharkelt were carried out in this study. At the model without winglet, it can be seen that the air flows beside the wing and the flow is concentrated at the end of wing. At the model of winglet or sharklet, the pressure on the bottom of the wing happens to be lower in the wide area than for model without winglet. At the analysis result, the air flowing next to the wing can be seen to go over and rotates over the main wing. The model with the sharklet shows that the flow rate is the fastest. In case of model with sharklet, it is thought that the maximum total pressure of flow is distributed at the bottom of the wing, which can further improve the lift force of the wing. It is thought that the analysis results in this study on the air flow due to the configuration of aircraft edge wing can be helped at its convergent research.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.311-314
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• 2007

Aerodynamic characteristics of an insect-type flapping wings were carried out to obtain the design parameters of Micro Hovering Air Vehicle. A pair of wing model was scaled up about 200 times and applied two pairs of 4-bar linkage mechanism to mimic the wing motion of a fruit fly(Drosophila). To verify the Weis-Fogh mechanism, a pair of wings revolved on the 'Delayed Rotation'. Lift and drag were measured in conditions of the Reynolds number based on wing tip velocity of about 1,200 and the maximum angle of attack of 40$40^{\circ}$. Inertia forces of a wing model were also measured by using a 99.98% vacuum chamber and subtracted on measured data in air. In the present study, high lift effect of Weis-Fogh mechanism was appeared in the middle of upstroke motion.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.4
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• pp.287-294
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• 2007

A static aeroelastic analysis for supersonic aircraft wing equipped with external store under the wing lower surface is performed using computational fluid dynamics (CFD) and computational structural technology(CST) coupling methodology. Two mapping algorithms, which are the pressure mapping algorithm and the displacement mapping algorithm, are used for CFD/CST coupling. A three-dimensional unstructured Euler code and finite element analysis program are used to calculate the flow properties and the structural displacements, respectively. The coupling procedure is repeated in an iterative manner until a specified convergence criterion is satisfied. Static aeroelastic analysis for a typical supersonic flight wing is performed and final converged wing configuration is obtained after several iterations.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.217-221
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• 2007

In this study, forced vibrations analysis was performed for main wing of small scale WIG vehicle which is equipped two-stroke pusher type propeller engine, in terms of structural. for the frequency response analysis, excitations were assumed by H-mode(Horizontal mode), X-mode(Twisted mode) which is main vibration mode of engine, and for the transient response analysis, excitations were assumed by L-mode(Longitudinal mode) with propeller thrust which is occurred when it revolution.