• Title/Summary/Keyword: airfoil

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Subsonic/Transonic Airfoil Design Using an Inverse Method (Inverse 기법을 이용한 아음속/천음속 익형 설계)

  • Lee Young-Ki;Lee Jae-Woo;Byun Yung-Hwan
    • Journal of computational fluids engineering
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    • v.3 no.1
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    • pp.46-53
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    • 1998
  • An inverse method for the subsonic and transonic airfoil design was developed using the Euler equations. Two testcases were performed. One was a verification of the method using the supercritical airfoil of the Korean mid-sized (100 passengers class) transport aircraft. The other was the design of an airfoil showing a good cruising performance (L/D ratio) in the high subsonic flow regime. These testcases demonstrated the efficiency and the robustness of the design method in the present study.

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CFD study of an airfoil for small wind turbine applications

  • Wata, Joji;Zullah, Mohammed Asid;Lee, Young-Ho
    • 한국신재생에너지학회:학술대회논문집
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    • 2011.05a
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    • pp.64.1-64.1
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    • 2011
  • Small horizontal axis wind turbines (HAWTs) can be used to produce power in areas where the wind conditions are not favorable or optimal for large HAWTs. A newly designed airfoil for use in small HAWTs was analyzed in CFD to predict the aerodynamic performance at various Reynolds numbers over a various angles of attack. The coefficient of lift and drag, CL and CD, and the pressure distribution over the airfoil was obtained. It was found that the airfoil could achieve very good aerodynamic characteristics. The results of the numerical analysis will be compared against experimental data for validation purposes.

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A Study on Discrete Frequency Noise from a Symmetrical Airfoil in a Uniform Flow (에어포일 이산소음 특성에 관한 연구)

  • Kim, H.J.;Lee, S.B.;Fujisawa, N.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.11b
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    • pp.646-651
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    • 2002
  • The flow field around a symmetrical airfoil in a uniform flow under the generation of noise was studied by experiments and numerical simulation. The experiments are conducted by visualizing the surface flow over the airfoil with a shear-sensitive liquid-crystal coating and by measuring the instantaneous velocity field around the trailing edge of the airfoil. The results indicate that the discrete frequency noise is generated when the separated laminar flow reattaches near the trailing edge of the pressure side and the turbulent boundary layer is formed over the suction side of the airfoil near the trailing edge. The periodic behavior of vortex formation was observed around the trailing edge and it persists further downstream in the wake. The frequency of the vortex formation in the wake was consistent with that of the discrete frequency noise.

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A Numerical Study on Unsteady Flowfield around a NACA 0021 Airfoil at High Angles of Attack (고영각 NACA 0021 익형 주위의 비정상 유동장에 대한 수치해석적 연구)

  • Kim, Sang Dug
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.28 no.2
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    • pp.12-17
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    • 2020
  • Even though the benefit of flight at high angle-of-attack is to be able to reduce the speed of flight and maneuvers in complex flight environment, the flight at high angle-of-attack, however, is easy to be in stall which is characterized by sever unsteady flow separation over an airfoil. Current unsteady numerical analysis using DES was conducted to predict the aerodynamic characteristics of a NACA 0021 airfoil at high angle-of-attack conditions. And this provides the comparison with the steady numerical one with the typical turbulence models. The unsteady calculation by DES is appropriate in terms of predicting the aerodynamic performance of NACA 0021 airfoil at high angle-of-attack conditions.

AERODYNAMIC DESIGN OPTIMIZATION OF ROTOR AIRFOIL WITH MULTIPLE CONSTRAINTS (다중제약조건을 가진 로터익형의 공력 최적 설계)

  • Lee, S.M.;Sa, J.H.;Jeon, S.E.;Kim, C.J.;Park, S.H.;Chung, K.H.
    • 한국전산유체공학회:학술대회논문집
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    • 2010.05a
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    • pp.55-59
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    • 2010
  • Aerodynamic design optimization of rotor airfoil has been performed with advanced design method for improved aerodynamic characteristics of ONERA airfoils as a baseline. A multiple response surface method is used to consider various consider various constraints in rotor airfoil design. Airfoil surface and mean camber line are modified using various shape functions. Numerical simulations are performed using KFLOW, a Navier-Stokes solver with shear stress transport turbulence model. The present design method provides favorable configurations for the high performance rotor airfoil. Resulting optimized air foils give better aerodynamic performance than the baseline airfoils.

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NUMERICAL SIMULATION OF A TRANSONIC AIRFOIL IN THE CLOUD WITH THE DROPLET-LADEN INVISCID AIR FLOW MODEL (액적이 있는 비점성 공기유동 모델을 이용한 구름속의 천음속 에어포일 수치해석)

  • Yeom, G.S.;Chang, K.S.;Baek, S.W.
    • 한국전산유체공학회:학술대회논문집
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    • 2011.05a
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    • pp.291-293
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    • 2011
  • In this paper, the problem of transonic aerodynamic characteristics of a NACA0012 airfoil is numerically investigated in the inviscid gas-droplet two-phase flow with the compressible two-fluid model. In the present study, the airfoil flight in the cloud is simulated by taking account of the viscous drag of the droplets, the heat transfer, the phase change, and the droplet fragmentation The two-fluid equation system is solved by the fractional-step method and the WAF-HIL scheme. The effects of size and volume fraction of the droplets on the flow characteristics of the airfoil in the cloud are elaborated and discussed.

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A Study on Optimal Aerodynamic Shape of Airfoil using a Genetic Algorithm (유전자 알고리즘을 사용한 공기역학적 Airfoil 형상 최적화)

  • Jung, Sung-Ki;Duong, Hoang Anh;Lee, Young-Min;Je, So-Young;Myong, Rho-Shin;Cho, Tae-Hwan
    • 한국전산유체공학회:학술대회논문집
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    • 2008.03b
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    • pp.377-380
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    • 2008
  • In this study, an aerodynamic shape optimization system was developed to study the optimal shape of airfoil. The system consists of GA (Genetic Algorithm) and CFD code based on the Navier-Stokes equation. Lift-drag ratio is chosen as the object function and optimization is conducted for PARSEC airfoil with nine design variables, which is very efficient in representing the surface geometry of airfoil.

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Control of Flow around an Airfoil Using Piezo-ceramic Actuators (압전세라믹 액추에이터를 이용한 익형 후류 제어)

  • Choi, Jin;Jeon, Woo-Pyung;Choi, Hae-Cheon
    • Proceedings of the KSME Conference
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    • 2000.04b
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    • pp.491-496
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    • 2000
  • The objective of this study is to increase lift and decrease drag of an airfoil by delaying flow separation with piezo-ceramic actuators. The airfoil used is NACA 0012 and the chord length is 30cm. An experiment is performed at the freestream velocity of 15m/s at which the Reynolds number is $3{\times}10^5$. Seven rectangular actuators are attached to the airfoil surface and move up and down based on the electric signal. At the attack angle of $16^{\circ}$, the separation point is delayed downstream due to momentum addition induced by the movement of the actuators. Drag and lift are measured using an in-house 2-dimensional load cell and the surface pressures are also measured. Lift is increased by 10%, drag is reduced by 50%, and the efficiency is increased to 170%. The flow fields with and without control are visualized using the smoke-wire and tuft techniques.

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Flow Visualization of an Unsteady Airfoil at Low Reynolds Numbers (저 레이놀즈수에서 비정상 에어포일의 흐름 가시화)

  • Kim, Dong-Ha;Chang, Jo-Won
    • Journal of the Korean Society of Visualization
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    • v.4 no.2
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    • pp.51-58
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    • 2006
  • A boundary layer visualization was carried out in order to investigate the influence of Reynolds number on an oscillating airfoil. An NACA 0012 airfoil is sinusoidally pitched at the quarter chord point with oscillation amplitude of ${\pm}6^{\circ}$. A smoke-wire technique was employed to visualize the boundary layer and the near-wake. The freestream velocities are 1.98, 2.83 and 4.03m/s and corresponding chord Reynolds numbers are $2.3{\times}10^4,\;3.3{\times}10^4$, and $4.8{\times}10^4$, respectively. As the reduced frequency of K=0.1 is fixed, the corresponding frequency of an airfoil was adjusted in each case. The results reveal that the point at which the shear stress in an unsteady boundary layer separation disappears does not correspond with the position of the breakdown of the boundary layer, and that the breakdown of the boundary layer occurs further downstream.

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Effect of the Gurney Flap on NACA 0015 Airfoil (NACA 0015 익형에 대한 Gurney 플랩의 영향)

  • Yoo, Neung-Soo;Lee, Jang-Ho
    • Journal of Industrial Technology
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    • v.20 no.B
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    • pp.71-76
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    • 2000
  • A numerical investigation was performed to determine the effect of the Gurney flap on NACA 0015 airfoil. A Navier-Stokes code. FLUENT, was used to calculate the flow field about the airfoil. The fully-turbulent results were obtained using the standard ${\kappa}-{\varepsilon}$ two-equation turbulence model. The numerical solutions showed the Gurney flap increased both lift and drag. These results suggested that the Gurney flap served to increase the effective camber of the airfoil. Gurney flap provided a significant increase in lift-to-drag ratio relatively at low angle of attack and for high lift coefficient. It turned out that 0.75% chord size of flap was best. The numerical results exhibited detailed flow structures at the trailing edge and provided a possible explanation for the increased aerodynamic performance.

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