• Title/Summary/Keyword: 버펫

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A New Steady Approach to Predict the Transonic Buffet Onset (천음속 버펫 발단 예측을 위한 새로운 정상 접근 방법)

  • Jeong, In-Jae
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.34 no.5
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    • pp.12-18
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    • 2006
  • A new steady approach has been developed to predict the transonic buffet onset of a high speed aircraft. In this paper, the flow is assumed to be steady for the buffet onset. The present study involves the analysis of a distinct change in the variation of various static aerodynamic parameters. These distinct changes indicates the onset of transonic buffet. Among the various aerodynamic parameters considered in this study, the variation in the center of pressure has shown to provide a clearest indicator of transonic buffet onset. This new steady approach can be applied to predict the transonic buffet onset for airfoils with shock induced separation bubble and for large swept wings with small aspect ratios. Good agreements have been obtained compared with unsteady wind tunnel buffet test data. Based on the results obtained the new steady approach, it can be newly suggested that the distinct slope changes of the center of pressure curve can be used as an indicator of buffet onset for the steady experimental method on a full aircraft configuration.

Prediction of Pressure Fluctuations on Hammerhead Vehicle at Transonic Speeds Using CFD and Semi-empirical Formula Considering Spatial Distribution (CFD와 공간분포를 고려한 반경험식을 이용한 해머헤드 발사체의 천음속 압력섭동 예측)

  • Kim, Younghwa;Nam, Hyunjae;Kim, June Mo;Sun, Chul
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.49 no.6
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    • pp.457-464
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    • 2021
  • To analyze the buffet phenomenon that causes serious vibration loads on a satellite launch vehicle, the pressure fluctuations on a hammerhead launch vehicle at transonic speeds are predicted by coupling CFD analysis and semi-empirical methods. From the RANS simulation, shock oscillation region, separation region, and separation reattachment region are identified, and the boundary layer thickness, the displacement thickness, and flow properties at boundary layer edge are calculated. The pressure fluctuations and power spectra on the hammerhead fairing are predicted by coupling RANS results and semi-empirical methods considering spatial distribution, and compared with the experimental data.

NUMERICAL INVESTIGATION OF SHOCK-BUFFET ON TRANSPORT AIRCRAFT WITH CHANGING THE POSITION OF NACELLE/PYLON (항공기 Nacelle/pylon 위치에 따른 Shock-Buffet 현상의 수치적 연구)

  • Kim, S.H.;Yee, K.J.;Oh, S.J.
    • Journal of computational fluids engineering
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    • v.19 no.3
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    • pp.69-76
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    • 2014
  • The shock buffet on a transonic transport aircraft are negative factors that reduce the aerodynamic performance of aircraft. The parametric studies were performed for position of nacelle/pylon to estimate the trend of flow mechanism under the wing that affects shock buffet. To generate external mesh of aircraft configuration that change the position of nacelle, snappyHexMesh provided in OpenFOAM was applied. Implicit density-based solver(ISAAC) was used for flow analysis. The change of nacelle position along horizontal direction dynamically affected the aerodynamic performance of transonic transport aircraft as comparing that of vertical direction. As a result of the parametric study of nacelle/pylon position, it was confirmed that the optimal position of nacelle can be obtained by aerodynamic design.

Structural Vibration Analysis of Helicopter Search Light Considering Aerodynamic Buffet Load (공력 Buffet 하증을 고려한 헬리콥터 탐색등의 구조진동해석)

  • Kim, Yo-Han;Kim, Dong-Man;Kim, Dong-Hyun;Choi, Hui-Ju;Park, Yong-Suk;Kim, jong-Gun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.11a
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    • pp.175-179
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    • 2008
  • In this study, computational structural vibration analysis of helicopter search light exposing unsteady buffet load have been conducted using combined advanced numerical methods. Unsteady CFD method based on Navier-Stokes equations is used to predict viscous buffet load due to flow separation effects. Full three-dimensional finite element model is constructed in order to conduct static and structural dynamic analyses of the search light model for two different typical flight speeds. Also, the correct performance of the search light can be physically estimated to examine the actual lighting area considering the effects of structural deformations.

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Structural Vibration Analysis of a Helicopter Search Light Considering Aerodynamic Buffet Load (공력 Buffet 하중을 고려한 헬리콥터 탐색등의 구조진동해석)

  • Kim, Yo-Han;Kim, Dong-Man;Kim, Dong-Hyun;Choi, Hui-Ju;Park, Yong-Suk;Kim, Jong-Gun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.9
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    • pp.870-875
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    • 2009
  • In this study, computational structural vibration analysis of helicopter search light exposing unsteady buffet load have been conducted using combined advanced numerical methods. Unsteady CFD method based on Navier-Stokes equations is used to predict viscous buffet load due to flow separation effects. Full three-dimensional finite element model is constructed in order to conduct static and structural dynamic analyses of the search light model for two different typical flight speeds. Also, the correct performance of the search light can be physically estimated to examine the actual lighting area considering the effects of structural deformations.