• 항공우주기술
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• 제1권2호
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• pp.1-10
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• 2002

본 연구에서는 전진익 소형기 항공기 형상에 대한 공력해석을 수행하였다. 전진익 소형 항공기는 주익의 평면형상이 후퇴각을 가진 스트레이크(strake) 형태의 안쪽(inboard) 날개와, 전진각을 가진 바깥쪽(outboard) 날개가 결합되어 있는 형태로 구성되어 있다. 이와 같은 두개의 다른 형태의 날개 평면형상의 결합으로 킹크(kink)로 정의되는 날개의 불연속선이 존재하게 되어, 이 부분에 의한 날개 공력특성의 면밀한 분석이 요구되었다. 전진익 소형 항공기에 대한 기본적 공력계수의 산출 및 유동해석은 해석방법 간의 차이에서 기인하는 정확도를 분석하기 위해 4가지의 방법으로 계산을 수행하였다. 항공기 형상에 대한 격자생성의 용이성을 위해 중첩격자기법(Chimera grid)을 적용하였다. 본 해석을 통하여 전진익 소형기 형상에 대한 기본적인 공력계수의 도출과 함께 주익에 대한 공력특성이 분석되었다.

• 한국항공운항학회지
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• 제18권4호
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• pp.1-8
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• 2010

In the aerospace field, the study on a morphing-wing is in progress to improve flight performance and perform multi flight mission. There are many concepts of morphing-wing such as camber-change, wing-twist, variable-span, and so on. In this study, the aerodynamic characteristics and flight control of an air vehicle with a variable-span morphing wing (VSMW) have been investigated. VSMW with symmetric span control(SSC) can increase cruising range of aircraft by reducing drag in various flight condition. VSMW with anti-symmetric span control(ASSC) can be used in the roll control of an aircraft. The flight control about pure rolling dynamic system and full dynamic system have been performed about the cruise missile.

• 한국항공우주학회지
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• 제45권10호
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• pp.817-824
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• 2017

꼬리날개 조종 유도무기의 주날개-꼬리날개 간섭 현상에 대한 연구를 수행하였다. 풍동시험 데이터를 이용하여 주날개-꼬리날개 간섭 정도를 산출하였으며 날개간의 간섭 현상이 전체 공력에 미치는 영향을 분석하였다. 성분 시험 결과를 이용하여 downwash angle을 산출하였으며 날개간의 간섭 영향을 받음각에 대한 비율로 나타내었다. 날개간의 간섭현상 발생 시 유동 특성을 살펴보기 위해 수치해석을 실시하였으며 받음각에 대한 vorticity 특성을 비교하였다. 실험적, 수치적 연구를 통해 주날개-꼬리날개 간섭현상이 유도무기의 정안정성에 큰 영향을 미침을 확인하였다.

• 한국항공우주학회지
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• 제30권3호
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• pp.37-45
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• 2002

옆미끄럼이 있는 조건에서 LEX를 갖는 $65^{\circ}$ 후퇴각 삼각날개의 와류와 공력 특성을 실험적으로 연구하였다. 자유 유동속도는 40m/sec이고 이 속도와 날개뿌리 시위를 기준으로 한 단위길이당 레이놀즈 수는 $1.76{\times}10^6$이다. 받음각 범위는 $12^{\circ}$ 부터 $28^{\circ}$ 까지 이고, 시험된 옆미끄럼각은 $0^{\circ}$ , $-10^{\circ}$ , $-20^{\circ}$ 이다. 날개의 바람쪽에 있는 LEX 와류는 바람 반대쪽 LEX 와류보다 훨씬 더 강하고 날개면에 더 가깝게 날개 후류영역으로 진입한다. LEX 와류와 날개 와류는 서로 연동하여 집중되고 강한 와류를 형성하거나 날개 하류지역에서 붕괴된다. LEX 와류와 날개 와류의 상호작용으로 인하여 바람쪽 날개면에는 높은 흡입압력이 유지되고, 바람 반대쪽 날개면에는 낮은 흡입압력이 형성된다.

• 한국군사과학기술학회지
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• 제5권3호
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• pp.77-86
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• 2002

An experimental study of the vortex interaction characteristics of a delta wing/LEX configuration was conducted in a wind tunnel using the micro water droplet and laser beam sheet visualization technique. The main focus of this study was to analyze the effect of the angle of attack and sideslip angle on the vortex interaction and vortex breakdown. These tests were accomplished at angles of attack between $16^{\circ}$ and $28^{\circ}$ and sideslip angle between $0^{\circ}$ and $-15^{\circ}$ at free-stream velocity of 6.2 m/s. Flow visualization data provide a description of the vortex interaction between LEX and wing vortices, and of the vortex breakdown. The introduction of LEX vortex stabilized the vortical flow, and delayed the vortex breakdown up to higher angle of attack. The vortex interaction and breakdown was promoted on the windward side, whereas they are suppressed on the leeward side.

• 한국전산유체공학회지
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• 제16권4호
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• pp.47-54
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• 2011

A rotating propeller of turboprop aircraft gives much effect on the aerodynamic characteristics of wing such as lift, moment and stall. Specially propeller effect on the wing surface is much more dominant when aircrafts are in landing or take-off conditions. In the present paper, three dimensional Navier-Stokes simulations for the interaction of propeller and wing were carried out for medium sized turboprop aircraft. For rotating propeller, unsteady sliding mesh method was used to simulate a relative motion between moving and static bodies. For the power effect analysis in landing and take off configurations, double slotted flap was also considered and the aerodynamic characteristics were investigated. It was shown that the propeller slipstream enhanced the lift slope including maximum lift by eliminating local flow separation region and this enhancement was more dominant with high lift device.

• Journal of Mechanical Science and Technology
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• 제18권6호
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• pp.1042-1051
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• 2004

The vortex flow characteristics of a sharp-edged delta wing at high angles of attack were studied using a computational technique. Three dimensional, compressible Reynolds-averaged Navier-Stokes equations were solved to understand the effects of the angle of yaw, angle of attack, and free stream velocity on the development and interaction of vortices and the relationship between suction pressure distributions and vortex flow characteristics. The present computations gave qualitatively reasonable predictions of vortical flows over a delta wing, compared with past wind tunnel measurements. With an increase in the angle of yaw, the symmetry of the pair of leading edge vortices was broken and the vortex strength was decreased on both windward and leeward sides. An increase in the free stream velocity resulted in stronger leading edge vortices with an outboard movement.

• International Journal of Aeronautical and Space Sciences
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• 제3권2호
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• pp.82-87
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• 2002

Aerodynamic analysis of NACA wings moving with a constant speed over guideways are performed using an indirect boundary element method (potential-based panel method). An integral equation is obtained by applying Green's theorem on all surfaces of the fluid domain. The surfaces over the wing and the guideways are discretized as rectangular panel elements. Constant strength singularities are distributed over the panel elements. The viscous shear layer behind the wing is represented by constant strength dipoles. The unknown strengths of potentials are determined by inverting the aerodynamic influence coefficient matrices constructed by using the no penetration conditions on the surfaces and the Kutta condition at the trailing edge of the wing. The aerodynamic characteristics for the wings flying over nonplanar ground surfaces are investigated for several ground heights.

• 한국군사과학기술학회지
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• 제9권4호
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• pp.104-113
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• 2006

To identify aeroelastic characteristics of wings with double-folding mechanism, aeroelastic analyses are performed. There are four wing models which consist of one linear model and three nonlinear models. The nonlinear models have one or two freeplay nonlinearties. The describing function method is used to approximately examine nonlinear effects. The aeroelastic module in MSC/NASTRAN is used to study the aeroelastic characteristics of the considered wing models. The effects of the folding mechanism and amplitude ratio are examined. As the amplitude ratio increases, the flutter speeds approach to those of the wing model with only one nonlinearity. The numerical results show that the flutter speeds of the wings with double-folding mechanism can be lower or higher than those of the wing model with only one folding mechanism depending upon the direction of the second folding mechanism.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.456-459
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• 2010

Icing is one of the most serious hazards for aircraft. The amount and rate of icing depend on a number of meteorogical and aerodynamic factors. Of primary importance are amount of liquid water content of droplets, their size, the temperature of aircraft surfaces, the collection efficiency, and the extent of supercooled droplets. In this study, in-flight icing analysis of low reynolds number high aspect ratio wing is carried out by using FENSAP-ICE. Each liquid water contents with altitude is obtained from FAR 25 Appendix-C. And the collectoin efficiency is calculated to check out the ice accretion position of wing with two angles of attack. The degradation of aerodynamic characteristics of aircraft are figured out by investigating the accretion of rime and glaze ice.