• Title, Summary, Keyword: supercritical airfoil

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Prediction of Transonic Buffet Onset for a Supercritical Airfoil with Shock-Boundary Layer Interactions Using Navier-Stokes Solver

  • Chung, Injae
    • International Journal of Aeronautical and Space Sciences
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    • v.18 no.1
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    • pp.1-7
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    • 2017
  • To predict the transonic buffet onset for a supercritical airfoil with shock-boundary layer interactions, a practical steady approach has been proposed. In this study, it is assumed that the airfoil flow is steady even when buffet onset occurs. Steady Navier-Stokes computations are performed on the supercritical airfoil. Using the aerodynamic parameters calculated from Navier-Stokes solver, various steady approaches for predicting buffet onset are discussed. Among the various steady approaches considered in this study, Thomas' criterion based on Navier-Stokes computation has shown to be the most appropriate indicator of identifying the buffet onset for a supercritical airfoil with shock-boundary layer interactions. Good agreements have been obtained compared with the results of unsteady transonic wind tunnel tests. The present method is shown to be reliable and useful for transonic buffet onset for a supercritical airfoil with shock-boundary layer interactions in terms of practical engineering viewpoint.

Aerodynamic Performance Improvement by Divergent Trailing Edge Modification to a Supercritical Airfoil

  • Yoo, Neung-Soo
    • Journal of Mechanical Science and Technology
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    • v.15 no.10
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    • pp.1434-1441
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    • 2001
  • A computational study has been performed to determine the effects of divergent trailing edge (DTE) modification to a supercritical airfoil in transonic flow field. For this, the computational result with the original DLBA 186 supercritical airfoil was compared to that of the modified DLBA 283. A wavier-Stokes code, Fluent 5. 1, was used with Spalart-Allmaras's one-equation turbulence model. Results in this study showed that the reduction in drag due to the DTE modification is associated with weakened shock and delayed shock appearance. The decrease in drag due to the DTE modification is greater than the increase in base drag. The effect of the recirculating flow region on lift increase was also observed. An airfoil with DTE modification achieved the same lift coefficient at a lower angle of attack while giving a lower drag coefficient. Thus, the lift-to-drag ratio increases in transonic flow conditions compared to the original airfoil. The lift coefficient increases considerably whereas the lift slope increases just a little due to DTE modification.

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Transonic Flutter Characteristics of Supercritical Airfoils Considering Shockwave and Flow Separation Effects (충격파 및 유동박리 효과를 고려한 초임계 에어포일의 천음속 플러터 특성)

  • Kim, Dong-Hyun;Kim, Yu-Sung;Kim, Yo-Han;Kim, Seok-Soo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.167-174
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    • 2008
  • In this study, flutter analyses for supercritical airfoil have been conducted in transonic region. Advanced computational analysis system based on computational fluid dynamics (CFD) and computational structural dynamics (CSD) has been developed in order to investigate detailed static and dynamic responses of supercritical airfoil. Reynolds-averaged Navier-Stokes equations with Spalart-Allmaras (S-A) and SST ${\kappa}-{\omega}$ turbulence models are solved for unsteady flow problems. A fully implicit time marching scheme based on the Newmark direct integration method is used for computing the coupled aeroelastic governing equations of cascades for fluid-structure interaction (FSI) problems. Also, flow-induced vibration (FIV) analyses for various supercritical airfoil models have been conducted. Detailed flutter responses for supercritical are presented to show the physical performance and vibration characteristics in various angle of attack.

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Transonic Flutter Characteristics of Supercritical Airfoils Considering Shockwave and Flow Separation Effects (충격파 및 유동박리 효과를 고려한 초임계 에어포일의 천음속 플러터 특성)

  • Lin, Han;Kim, Dong-Hyun;Kim, Yu-Sung;Kim, Yo-Han;Kim, Seok-Soo
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.17 no.2
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    • pp.8-17
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    • 2009
  • In this study, flutter analyses for supercritical airfoil have been conducted in transonic region. Advanced computational analysis system based on computational fluid dynamics (CFD) and computational structural dynamics (CSD) has been developed in order to investigate detailed static and dynamic responses of supercritical airfoil. Reynolds-averaged Navier-Stokes equations with Spalart-Allmaras (S-A) and SST ${\kappa}-{\omega}$ turbulence models are solved for unsteady flow problems. A fully implicit time marching scheme based on the Newmark direct integration method is used for computing the coupled aeroelastic governing equations of cascades for fluid-structure interaction (FSI) problems. Also, flow-induced vibration (FIV) analyses for various supercritical airfoil models have been conducted. Detailed flutter responses for supercritical are presented to show the physical performance and vibration characteristics in various angle of attack.

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Effect of Divergent Trailing Edge Modification of Supercritical Airfoil in Transonic Flow (천음속유동에서 초임계익형 후연확대수정의 영향)

  • Yoo, Neung-Soo
    • Journal of Industrial Technology
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    • v.17
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    • pp.183-189
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    • 1997
  • The computation of the flow around a supercritical airfoil with a divergent trailing edge(DTE) modification(DLBA 243) is compared to that of original supercritical airfoil(DLBA 186). For this computation, Reynolds-Averaged Navier-Stokes equations are solved with a linearized block implicit ADI method and a mixing length turbulence model. Results show the effects of the shock and separated flow regions on drag reduction due to DTE modification. Results also show that DTE modification accelerates the boundary layer flow near the trailing edges which has an effect similar to a chordwise extension that increases circulation and is consistent with the calculated increase in the recirculation region in the wake. Airfoil with DTE modification achieves the same lift coefficient at a lower incidence and thus at a lower drag coefficient, so that lift-to-drag ratio is increased in transonic cruise conditions compared to the original airfoil. The reduction in drag due to DTE modification is associated with weakening of shock strength and delay of shock which is greater than the increase in base drag.

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Aerodynamic performance of Modified Sonic Arc Airfoil (수정 Sonic Arc 익형의 공력성능)

  • Lee, Jang-Chang
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.35 no.7
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    • pp.581-585
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    • 2007
  • Sonic arc airfoil derived from the TSD theory is modified to new airfoil shape and its aerodynamic performance in transonic flow is investigated. The numerical simulation using Euler equations for the modified sonic arc airfoil is performed. The numerical results are compared with the aerodynamic performance of NACA0012 airfoil, of supercritical airfoil, and of NACA64A210 airfoil. In the same free stream Mach number of transonic flow, the pressure drag of the modified sonic arc airfoil is smaller than that of NACA0012 airfoil and the lift-drag ratio of the modified sonic arc airfoil is much larger than that of NACA0012 airfoil. In the comparison of the drag-divergence Mach number of transonic flow, the drag-divergence Mach number of the modified sonic arc airfoil is larger than that of NACA64A210 airfoil but is smaller than that of supercritical airfoil.

Airfoil Aerodynamic Analysis for Supersonic Business Jet Design (Supersonic Business Jet 설계를 위한 날개 단면 공력 해석)

  • Jang, Won-Geun;Jo, Du-Hyeon;Kim, Chan-Hui;Kim, Hae-Sol;Lee, Jung-Hyeon;Kim, Dong-U;Choe, Seong-Im
    • Proceeding of EDISON Challenge
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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.

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Application of EDISON CFD in The Aerodynamic Design for Supercritical Airfoil (EDISON CFD를 이용한 초임계 에어포일의 공력설계)

  • Yu, Hong-Seok;Lee, Jang-Chang
    • Proceeding of EDISON Challenge
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    • pp.343-348
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    • 2013
  • 초임계 익형은 천음속 영역에서 비행하는 상업용 민간 항공기와 전투기 날개의 공력성능을 향상시키기 위해 Whitcomb R. T.가 제안 하였다. 초임계 익형은 상부표면을 평평하게 디자인하여 임계마하수보다 큰 마하수에서 나타나는 익형 주위의 충격파 출현을 지연시킴으로써 항력을 줄일 수 있고, 상부 표면의 평면 설계로 인한 양력 감소를 보정하기 위하여 하부 표면의 꼬리부분에 캠버가 있는 형상을 하고 있다. 본 연구에서는 EDISON CFD를 이용하여, 초임계 익형의 공력특성을 해석하고 Xfoil의 data와 비교 분석하였다. 또한, 초임계 익형의 형상을 변경하여 두께와 뒷전 캠버가 다른 초임계 익형을 설계하였다. 새로운 초임계 익형의 형상은 상용 프로그램 Maple12을 이용하여 Whitcomb Integral Supercritical Airfoil의 형상을 수정하여 구할 수 있다. 초임계 익형 주위의 유동을 2D압축성 유동으로 가정하고 EDISON CFD의 2D_Comp-2.0 솔버를 사용하여 수치해석을 수행하였다.

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

  • Lee Jae Woo;Lee Young-Ki;Byun Yung-Hwan
    • 한국전산유체공학회:학술대회논문집
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    • pp.61-66
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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 design of the supercritical airfoil, aiming to be used for 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/transonic flow regimes. These testcases demonstrated the efficiency and the robustness of the developed method.

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A Numerical study of flowfield around a transonic airfoil accompanying shock (충격파를 동반한 천음속 에어포일 주위의 유동 수치해석)

  • Kim, Jae-Min;Kim, Mun-Sang
    • Proceeding of EDISON Challenge
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    • pp.415-420
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    • 2013
  • 천음속 영역에서 비행하는 에어포일 주위의 유동은 아음속 영역과는 달리 충격파(Shockwave)를 동반하고 이에 따라 복잡한 유동 현상이 발생한다. 본 연구는 천음속 영역에서 설계된 에어포일 주위의 유동에서 충격파 발생에 따른 유동변화의 특징들을 관찰하였다. 특히, 충격파에 의해서 발생하는 진동(Buffeting)과 경계층 유동 박리(Shock-induced boundary layer separation)현상에 대한 관찰과 일반적인 에어포일과 초임계 에어포일(Supercritical airfoil)간의 유동 특성의 차이점을 분석하였다. 본 연구를 위해서 EDISON CFD코드가 사용되었다.

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