• 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.

• The Journal of the Convergence on Culture Technology
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• v.6 no.1
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• pp.501-506
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• 2020

In this experimental study, we have analyzed aerodynamic performance of the four representative types of passenger car vehicles, different types of side window angles, different types of engine hood angles, and the angle difference of the roof line in order to comprehensively analyze how the aerodynamic performance varies with different shape of vehicle. Experiment results showed that the rear window falling at aa certain angle lowered aerodynamic performance, angle difference of the lowered roof line did not affect aerodynamic performance, and the back window line falling at certain angles had no visible effect on aerodynamic performance. Back window line leaning towards front side may help enhance styling aesthetics, but aerodynamic performance decreased. In case of rear diffuser installation, aerodynamic performance also decreased.

• Journal of Aerospace System Engineering
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• v.9 no.1
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• pp.7-11
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• 2015

최근 무인기와 초소형비행체를 위한 프로펠러 연구수요가 증가하고 있다. 일반적인 프로펠러와 다른 점은 저 레이놀즈수 유동조건에서 구동된다는 점이다. 본 연구는 저 레이놀즈수 유동조건에서 비행하는 인간 동력 항공기를 위한 프로펠러 공력설계 및 성능해석에 관한 연구다. 저 레이놀즈수 유동조건에서 발생하는 공력천이현상을 고려한 3차원 공력특성 변화를 정확히 반영하지 못하는 상용 프로그램의 단점을 보완하여 프로펠러 공력설계 및 성능해석이 가능한 프로그램을 개발했다. 개발된 프로그램으로 인간 동력 항공기 설계요구조건에 충족하는 프로펠러 공력설계 및 성능해석을 수행하였다. 또한 프로펠러 회전수와 장착각도 변화에 따른 성능변화를 예측하여 비행당시 상황에 따라 비행 가능한 성능출력이 가능하도록 하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1998.10a
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• pp.39-39
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• 1998

본 연구는 500KW급 수평축 풍력발전기용으로 개발된 회전날개의 시제품 제작에 앞서 축소모델에 대한, 이론적으로 예측된 공력성능과 신축에 의한 공력성능을 비교 검토함으로서, 설계결과를 검증하고, 필요한 경우 설계를 보완하여 개발위험도를 최소화하기 위해 수행되었다. 시험모델의 크기는 실제의 5%로서 직경이 2.1m이며 날개의 시위길이는 0.2r/R에서 0.101m, 날개끝에서 0.043m 이고, 날개단면형 상온 FX-S-03-182이다. 블레이드의 재질은 Glass/Epoxy 복합재료로 제작되었으며, 실제 풍황을 모사하기 위해 자연풍 상태에서 실험하였다. 실험장치의 구성은 15m 높이의 타워에 회전날개와 전자브레이크 및 각종 센서를 장착하였고, 날개가 회전하기 시작하면 제동장치에 의해 부하를 주면서 토크, 회전수, 풍속 등을 각각의 센서로부터 자료획득장치를 통해 자료처리를 할 수 있도록 하였다. 실험하는 동안 풍속은 4m/s-13m/s 정도로서 시동 풍속인 4m/s와 정격풍속인 12m/s를 포함하여 회전날개의 전체적인 특성을 파악하기 용이하였고, 이론적인 예측성능과 측정된 성능을 비교 검토한 결과 비슷한 결과를 얻어 공력설계 및 해석 방법을 검증하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.7
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• pp.13-18
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• 2004

This paper describes an efficient and robust optimization method for helicopter rotor airfoil design in forward flight. Navier-Stokes analysis was employed to compute the dynamic response of an airfoil, which simulates the unsteady rotor flow-field in forward flight. The optimization system consists of two categories; Response Surface Method to construct the response surface model based on D-optimal 3-level factorial design, and Genetic Algorithm to obtain the optimum solution of a defined objective function including penalty terms of constraints. The influence of design variables and their interactions on the aerodynamic performance was examined through the optimization process.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.8
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• pp.26-33
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• 2005

Smart UAV, which adopting tiltrotor aircraft concept, requires vertical take-off and landing, long endurance and high speed capability. These contradictable flight performances are hard to meet unless the operation of flap system which should reveal optimal performance for each flight mode. In order to design SUAV flaperon satisfying the three performance requirements, various configurations are generated and their aerodynamic performances are analyzed using numerical flow computations around flap systems. Considering aerodynamic performance and structural simplicity, a final flap configuration is selected and the performance is validated through the wind tunnel testing for 40% scale model.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.1
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• pp.9-19
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• 2017

In this study, stator shroud injection in a single-stage transonic axial compressor is proposed. A parametric study of the effect of stator shroud injection on aerodynamic performances was conducted using the three-dimensional Reynolds-averaged Navier-Stokes equations. The curvature, length, width, and circumferential angle of the stator shroud injector and the air injection mass flow rate were selected as the test parameters. The results of the parametric study show that the aerodynamic performances of the single-stage transonic axial compressor were improved by stator shroud injection. The aerodynamic performances were the most sensitive to the injection mass flow rate. Further, the total pressure ratio and adiabatic efficiency were the maximum when the ratio of circumferential angle was 10％.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.10
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• pp.891-898
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• 2007

Optimal aerodynamic design for the pitch-controlled horizontal axis wind turbine and its aerodynamic performance for various pitch angles are performed numerically by using the blade element momentum theory. The numerical calculation includes effects such as Prandtl‘s tip loss, airfoil distribution, and wake rotation. Six different airfoils are distributed along the blade span, and the special airfoil i.e. airfoil of 40% thickness ratio is adopted at the hub side to have structural integrity. The nonlinear chord obtained from the optimal design procedure is linearized to decrease the weight and to increase the productivity with very little change of the aerodynamic performance. From the comparisons of the power, thrust, and torque coefficients with corresponding values of different pitch angles, the aerodynamic performance shows delicate changes for just $3^{\circ}$ increase or decrease of the pitch angle. For precisive pitch control, it requires the pitch control algorithm and its drive mechanism below $3^{\circ}$ increment of pitch angle. The maximum torque is generated when the speed ratio is smaller than the designed one.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.9
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• pp.16-26
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• 2005

The aerodynamic design of a proprotor for the Smart UAV adopting tiltrotor aircraft concept is conducted in this study. Since proprotor of tiltrotor aircraft is operated at both rotary and fixed wing mode with single configuration rotor, the proprotor has to be designed to meet performance requirements for both flight modes. The aerodynamic design of proprotor is accomplished by combining three sources of data - the proprotor performance data, the aerodynamic data of vehicle, and the performance data of engine. The performance analysis code for proprotor is based on the combined momentum and blade element theory and validated by comparison with the TRAM data. In order to design configuration for a proprotor satisfying requirements for both rotary and fixed wing mode, various kind of performance maps are constructed for many performance and configuration parameters. From the analysis the twist angle of 38 degrees and the solidity of 0.118 are decided to be the optimal geometric parameters for both operating conditions.

• Proceeding of EDISON Challenge
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• 2012.04a
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• pp.89-92
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• 2012

초음속 항공기를 설계하는데 있어서 일반적인 항공기와는 다른 성능이 요구되는데 그것은 바로 초음속에 의한 충격파가 발생시키는 추가적인 항력을 감소시키는 일이다. 날개의 Airfoil 형상을 결정하기 위해서는 공력 특성을 파악해야 하는데, 이를 알아보는 데 있어서 EDISON_CFD를 사용하였다. 충격파의 생성을 지연시키는 Supercritical Airfoil의 여러 형상에 필요한 격자를 생성하여 비점성, 압축성 유동 해석을 수행하였다. 비교에 필요한 다섯 개의 NASA Supercritical Airfoil을 선정하여, 아음속과 초음속으로 나누어 받음각에 따른 양력계수와 항력계수를 도출하고, 이를 토대로 양항비를 추정해 보았다. 추려진 것 중 가장 우수한 공력성능을 보이는 airfoil을 선정하였는데 그 결과 NASA SC-0403 airfoil의 공력 성능이 가장 뛰어나 그것을 선정하기로 하였고, 또한 2차원 공력 해석에서 얻은 양력계수를 면적에 대하여 적분하여 날개에서의 양력과 항력을 추정하였다.