• Title, Summary, Keyword: 측풍

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활주로에 불어오는 측풍이 이·착륙 비행 안정성에 미치는 영향에 대한 이차원 유동해석

  • Kim, Si-Jin;Nam, Jeong-Su;Park, Sang-Hyeon
    • Proceeding of EDISON Challenge
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    • pp.594-599
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    • 2015
  • 활주로에서 발생하는 측풍이나 돌풍 등은 항공기의 이 착륙 안정성에 큰 영향을 미친다. 일반적으로 활주로를 건설 할 때 측풍에 대하여 많은 고려를 하지만, 이는 단순히 건설지형 주변에서 발생되는 기상 현상에 대한 데이터를 사용할 뿐 활주로가 완성된 이후에는 활주로 주변 지형 및 환경이 변하게 되어 활주로 건설 초기에 측정된 풍향이나 풍속이 크게 변할 수 있다. 따라서 측풍이 불어올 때, 활주로 주변 시설물에 의한 유동변화가 항공기의 이 착륙 비행 안정성에 미치는 영향이 고려되어야 하다. 본 연구에서는 3차원 형상의 활주로와 주변 시설물을 2차원으로 가정하여 활주로 주위 유동해석을 전산유체역학을 통해 계산하고, 유동변화가 이 착륙하는 비행기에 미치는 영향을 알아본다.

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A Study on Prediction Method of Derailment Behaviors due to Cross-wind Considering Dynamic Effects of Wheel-rail Interaction (차륜-레일의 동적효과를 고려한 측풍 원인 탈선 예측방법 연구)

  • Kim, Myung Su;Koo, Jeong Seo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.7
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    • pp.699-709
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    • 2014
  • This paper proposes a new method for predicting the derailment of a running train under cross-wind conditions, using the single wheelset derailment theory. The conventional theories used for predicting the derailment due to cross-winds were developed under the assumption that derailment will always be of the roll-over type, thus neglecting other possible types such as wheel-climbing, which may occur under special driving conditions. In addition, these theories do not consider running conditions such as dynamic wheel-rail interactions and friction effects. The new method considers the effects of dynamic wheel-rail interaction as well as those of lateral acceleration, rail cant, and cross-winds. The results of this method were compared and verified with those of the conventional methods and numerical simulations.

Experimental Study on the Aerodynamic Characteristics of the Ducted Fan for a Small UAV (소형 무인기 추진용 덕티드 팬의 공력특성에 관한 실험적 연구)

  • Kim, Jae-Kyeong;Choi, Hyun-Min;Cha, Bong-Jun;Lee, Sang-Hyo;Cho, Jin-Soo
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.251-256
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    • 2008
  • The experimental analysis on a ducted fan for the propulsion system of a small UAV were performed. To investigate the aerodynamic characteristics of the ducted fan, flow fields at inlet and outlet were measured using a hot-wire anemometry. Thrusts were measured with the six-component balance with due regard to the cross wind. To reproduce the cross wind effect, the ducted fan was aligned to $90^{\circ}$ rotated direction against flow direction in the wind tunnel. In this paper, the variation of the flow fields and thrust according to the cross wind were analyzed.

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Measurement of Aerodynamic Loads on Railway Vehicles Under Crosswind (측풍 시 철도차량에 가해지는 공기역학적 하중의 측정)

  • Kwon, Hyeok-Bin;You, Won-Hee;Cho, Tae-Hwan
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.1
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    • pp.91-98
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    • 2011
  • In this study, we measure the aerodynamic forces acting on an AREX train in a crosswind by wind tunnel testing. A detailed test model scaled to 5% of the original and including the inter-car, under-body, and the bogie systems was developed. The aerodynamic forces on the train vehicles have been measured in a 4 m $\times$ 3 m test section of the subsonic wind tunnel located in Korea Aerospace Research Institute (KARI). The aerodynamic forces and moments of the train model on two different track models have been plotted for various yaw angles, and the characteristics of the aerodynamic coefficients have been analyzed at the experimental conditions.

An Experimental Study on Aerodynamic Performance of a Rotor-Blade Configuration under Cross-Wind Conditions (측풍 조건을 고려한 로터블레이드 형상의 공력성능에 대한 실험적 연구)

  • Kang, Seung-Hee;Ryu, Ki-Wahn
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.25 no.2
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    • pp.63-68
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    • 2017
  • In the present study, a wind tunnel test for a rotor-blade configuration was conducted to investigate a basic aerodynamic performance and a effect of the cross wind. The diameter of the configuration was 1.46 m and the test was carried out for both a clean and a tripped configurations. The boundary layer for the trip configuration was simulated by zig-zag tape and the test performed on constant-velocity and constant-rotational modes. It was shown that the test result for the tripped configuration reduces the maximum power coefficient by 9.4% ~ 12.1% compared to the clean one. Within $5^{\circ}$ of the flow angle, there is no significant loss of power, however, the coefficient is reduced by 5.3% ~ 36.7% in the range of $10^{\circ}{\sim}30^{\circ}$.

A study on the reduction in angle of attack by the constructions in the vicinity of airport runway with crosswind (활주로 주변 건물을 지나는 측풍에 의한 이.착륙 항공기의 받음각 감소에 관한 연구)

  • Hong, Gyo-Young;Sheen, Dong-Jin;Park, Soo-Bok
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.17 no.2
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    • pp.1-7
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    • 2009
  • This paper illustrates how simulation modeling can be of substantial help in designing constructions in the vicinity of airport runway and presents results about the influence of aircraft wake vortices through computer simulation. The cross-wind energy dissipation rate is estimated from the Y-directional velocity spectrum for a sample in a real meteorological observation data. The eddy region about cross wind in the vicinity of airport runway is highly dependent on the height and shape of the buildings and the AOA of aircraft is greatly influenced by Y-directional velocity occurred by dint of separation region in runway.

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Numerical analysis of flow field around an automobile with variation of yaw angles (측풍의 편향각 변화에 따른 자동차 주위의 유동해석)

  • Kang D. M.;Jung Y. R.;Park W. G.;Ha S. D.
    • Journal of computational fluids engineering
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    • v.4 no.3
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    • pp.1-11
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    • 1999
  • This paper describes the flow field analysis of an automobile with crosswind effects of 15°, 30° 45° and 60° of yaw angles. The governing equations of the 3-D incompressible Navier-Stokes equations are solved by the iterative time marching scheme. The Chimera grid technique has been applied to efficiently simulate the flow around the side-view mirror. The computated surface pressure coefficients have been compared with experimental results and a good agreement has been achieved. The A- and C-pillar vortex and other flow phenomena around the ground vehicle are evidently shown. The variation of aerodynamic coefficients of drag, lift, side force and moments with respect to yaw angle is systematically studied.

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The 3D Numerical Analysis on the Predictions of Flight Stability at Take-off and Landing (Crosswind 60°) (이.착륙 비행 안정성 예측을 위한 3차원 수치해석(측풍 60° 방향))

  • Sheen, Dong-Jin
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.20 no.1
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    • pp.94-102
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    • 2012
  • The aim of this paper is to research the change in the turbulent flow and the AOA occurred by $60^{\circ}$ crosswind to the direction of runway through the three-dimensional numerical analysis and to predict the take-off and landing flight stability. As a result, the maximum amplitude of AOA variation on runway reached $4.88^{\circ}$ within 7 second because of the wake formed by the constructions in the vicinity of the airport, and the overall effects appeared as an irregular aperiodic forms. Additionally, it was observed that the layout and shape of the buildings effected on the strength of turbulence directly, and the rapid flow generated between the buildings changed into stronger wake and eventually expected that the flow raises serious take-off and landing flight instability.

Empennage Design of Solar-Electric Powered High Altitude Long Endurance Unmanned Aerial Vehicle (고고도 장기체공 전기 동력 무인기의 꼬리 날개 설계)

  • Hwang, Seung-Jae;Lee, Yung-Gyo;Kim, Cheol-Wan;Ahn, Seok-Min
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.41 no.9
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    • pp.708-713
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    • 2013
  • KARI is developing a solar-electric powered HALE UAV(EAV-3). For demonstrating the technology, EAV-2H, a down-scaled version of EAV-3, is developed and after EAV-2H's initial flight test, the directional stability and control need to be improved. Thus, the vertical tail and rudder of EAV-2H are redesigned with Advanced Aircraft Analysis(AAA). Size of the rudder is increased from mean chord ratio of rudder to vertical tail, $C_r/C_v(%)=30$ to $C_r/C_v(%)=60$ and size of the vertical tail is reduced 15%. As a result, the directional control to side wind($v_1$) is improved to sideslip angle, ${\beta}(deg)=25^{\circ}$ and $v_1(m/sec)=3.54$. Also, variation of airplane side force coefficient with sideslip angle ($C_{y_{\beta}}$) and variation of airplane side force coefficient with dimensionless rate of change of yaw rate ($C_{y_r}$) are reduced 15% and 22%, respectively to minimize the effect of side wind. The empennage design of EAV-2H is verified with flight tests and applied to design of KARI's solar-electric-powered EAV-3.