• 제목/요약/키워드: Attack Angle

검색결과 740건 처리시간 0.028초

Study on the Affects of Mounting Axisymmetric Inlet to Airframe

  • Ando, Yohei;Matsuo, Akiko;Kojima, Takayuki;Maru, Yusuke;Sato, Tetsuya
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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    • pp.699-702
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    • 2004
  • In this study, the affect of mounting axisymmetrical supersonic inlet to airfoil, which has 65 degree swept angle was numerically investigated. The parameter for this calculation are tree stream Mach number M=2.0 and 2.5, the distance between inlet spike and airfoil lower surface $L_{sw}$/$R_{cowl}$ = 1.21-1.54 and angle of attack to the airfoil 0-4. The mass capture ratio improved 3points in M=2.0 condition and 1points in M=2.5 while the mass capture ratio without airfoil surface was 57% and 71 % for each case. These are the result from increase of density and change of velocity deflection by the shock wave structure formed between inlet and airfoil surface. On the other hand, the distortion of Mach number at cowl lip plane increased by 13% in M=2.0, 3% in M=2.5 condition. The effects of the angle attack on the mass capture ratio is greater than that of the shock wave interaction between inlet and cowl, but the effects to the distortion is smaller in the range of this calculation condition. In the condition of M=2.0 with 4 degrees of angle of attack, inlet distortion of Mach number is mainly caused by the affects of the shock wave interaction between inlet and airfoil surface, while the largest angle of the velocity vector in the radial direction at cowl lip plane is caused by the affect of angle of attack. This large velocity vector made the flow inside the cowl subsonic and caused spillage, which interfere with the boundary layer of airfoil surface.

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DACS형 직격요격비행체의 비선형 가속도 조종루프 설계 (Nonlinear Acceleration Controller Design for DACS Type Kill Vehicle)

  • 이창훈;김태훈;전병을
    • 한국추진공학회지
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    • 제19권3호
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    • pp.54-64
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    • 2015
  • 본 논문에서는 DACS(Divert and Attitude Control System)를 장착한 KV(kill vehicle)의 비선형 가속도 조종루프 설계에 대해서 다룬다. ACS(Attitude Control System)는 받음각을 0으로 유지시키는 추력을 유발시키며, 받음각 제어를 위해 ACS를 제어명령으로 사용하는 궤환선형화 기반 비선형 받음각 조종루프를 제안한다. 받음각이 0인 조건에서는 비행경로각과 자세각이 일치하기 때문에 DCS(Divert Control System)는 유도루프에서 요구하는 측방향 가속도를 직접 생성하도록 제어한다. 이러한 방식에서는 추력에 의한 공력간섭 효과를 최소화 시킬 수 있으며, DCS와 ACS의 운용로직을 단순화 시킬 수 있다. 수치 시뮬레이션을 통해 제안한 기법의 성능을 검증한다.

받음각이 큰 평판 채널 내의 역류 유동 해석 (Flow Analysis of Reverse Flow in a Channel with High Angle of Attack)

  • 최승;손창현
    • 한국가시화정보학회지
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    • 제5권1호
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    • pp.37-42
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    • 2007
  • Reverse flow occurs in a channel when there is an obstruction at the entry. However it has been shown recently that reverse flow can be realized without an obstruction, by staggering the sides of the channel and placing it at an angle of attack to the oncoming flow. In this study the latter flow is computationally investigated. Studies have been carried out for different widths (gap between the two walls forming the channel), and at an angle of attack of 30. The results have captured all the essential features of this complex phenomenon and show the time dependent pumping mechanism which leads to the occurrence of reverse flow.

대형축류팬의 실속과 대책 (Stall and Counter-measure for Large Size Axial-Flow Fan)

  • 심의보
    • 유체기계공업학회:학술대회논문집
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    • 유체기계공업학회 1998년도 유체기계 연구개발 발표회 논문집
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    • pp.70-77
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    • 1998
  • The rise in pressure across the impeller blade of an axial flow fan depends on the angle of attack. At a low back pressure, the air volume will be large and the angle of attack is small. The gradual increase of the back pressure approached stall zone which is not stationary but travels blade to blade passage. In consequence, a region occurs around these blades with large vibration in the flow. To avoid these stall operation, the stall detector in the axial flow fans has been designed to detect stalling condition with a manometer or differential pressure switch by electric mechanism.

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Calculating Dynamic Derivatives of Flight Vehicle with New Engineering Strategies

  • Mi, Baigang;Zhan, Hao;Chen, Baibing
    • International Journal of Aeronautical and Space Sciences
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    • 제18권2호
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    • pp.175-185
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    • 2017
  • This paper presents new differential methods for computing the combined and single dynamic stability derivatives of flight vehicle. Based on rigid dynamic mesh technique, the combined dynamic stability derivative can be achieved by imposing the aircraft pitching to the same angle of attack with two different pitching angular velocities and also translating it to the same additional angle of attack with two different rates of angle of attack. As a result, the acceleration derivative is identified. Moreover, the rotating reference frame is adopted to calculate the rotary derivatives when simulating the steady pull-up with different pitching angular velocities. Two configurations, the Hyper Ballistic Shape (HBS) and Finner missile model, are considered as evaluations and results of all the cases agree well with reference or experiment data. Compared to traditional ones, the new differential methods are of high efficiency and accuracy, and potential to be extended to the simulation of combined and single stability derivatives of directional and lateral.

적응진화 알고리즘을 이용한 항공기의 고공격각 비행 제어를 위한 퍼지 제어기 설계 (A Design of Fuzzy Logic Controllers for High-Angle-of-Attack Flight Control of Aircraft Using Adaptive Evolutionary Algorithms)

  • 원태현;황기현;박준호;이만형
    • 제어로봇시스템학회논문지
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    • 제6권11호
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    • pp.995-1002
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    • 2000
  • In this paper, fuzzy logic controllers(FLC) are designed for control of flight. For tuning FLC, we used adaptive evolutionary algorithms(AEA) which uses a genetic algorithm(GA) and an evolution strategy (ES) in an adaptive manner in order to take merits of two different evolutionary computations. We used AEA to search for optimal settings of the membership functions shape and gains of the inputs and outputs of FLC. Finally, the proposed controller is applied to the high-angle-of-attack flight system for a supermaneuverable version of the f-18 aircraft and compares with other methods.

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Evaluation of the Performance of Re-entry System for the Typical Uncertainties

  • L., Daewoo;C., Kyeumrae;P., Soohong
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 2001년도 ICCAS
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    • pp.156.4-156
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    • 2001
  • The uncertainties of an atmospheric re-entry flight with respect to stability and controllability are aerodynamic error, measurement error of the angle of attack, variation of dynamic pressure, wind, and trim position of the control surfaces, etc. During hypersonic flight, a future angle of attack is biased from a nominal schedule. In order words, because the angle of attack is estimated from the navigation data, estimation error occurs due to wind, atmospheric density variation, etc. Error models used in this study, include a standard deviation of +-3 sigma, and are the normal distribution of statistics. This paper shows the appraisement of tracking performance onto the reference trajectory, satisfaction of the initial condition of TAEM about the re-entry system.

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Design of FLC for High-Angle-of-Attack Flight Using Adaptive Evolutionary Algorithm

  • Won, Tae-Hyun;Hwang, Gi-Hyun;Park, June-Ho;Lee, Man-Hyung
    • Journal of Mechanical Science and Technology
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    • 제17권2호
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    • pp.187-196
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    • 2003
  • In this paper, a new methodology of evolutionary computations - An Adaptive Evolutionary Algorithm (AEA) is proposed. AEA uses a genetic algorithm (GA) and an evolution strategy (ES) in an adaptive manner in order to take merits of two different evolutionary computations : global search capability of GA and local search capability of ES. In the reproduction procedure, the proportions of the population by GA and ES are adaptively modulated according to the fitness. AEA is used to. designing fuzzy logic controller (FLC) for a high-angle-of-attack flight system for a super-maneuverable version of F-18 aircraft. AEA is used to determine the membership functions and scaling factors of an FLC. The computer simulation results show that the FLC has met both robustness and performance requirements.

주기적 통과 후류가 익형위 박리 유동에 미치는 영향 (Effect of periodic wakes on separated flows over a NACA0012 airfoil)

  • 이희강;박태춘;전우평;강신형
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2004년도 춘계학술대회
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    • pp.1619-1624
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    • 2004
  • Experimental study of separated flow over a NACA0012 airfoil is conducted at $Re=2{\times}10^5$ when periodic wakes pass over the airfoil. The wakes are periodically generated by circular cylinders upstream of the airfoil. The measurement of surface pressure and surface visualization at various angles of attack are carried out without and with passing wakes. Without passing wakes, a separation bubble at the leading edge of the suction surface is formed at an angle of attack, found from a local plateau in the streamwise pressure distribution and two distinct lines in the surface flow visualization. With passing wakes, however, the bubble disappears. Owing to passing wakes, the lift increases at high angle of attack and the angle of stall also increases.

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비선형 와류격자법을 이용한 작은 종횡비 날개의 고받음각 및 지면효과 후류 특성 분석 (Wake Characteristics of High Angle of Attack and Ground Effect for Low Aspect Ratio Wings using NLVLM)

  • 이세욱
    • 융복합기술연구소 논문집
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    • 제4권1호
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    • pp.37-41
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    • 2014
  • For the analysis of lifting surface at high angle of attack, a Nonlinear Vortex Lattice Method(NLVLM) was used. The NLVLM is intented to compute the interactions between lifting surfaces and separated vertical flow. The lifting surfaces are represented by a lattice of discrete vortex rings. And wakes are represented by families of non-lintersecting, semi-infinite vortex line segments. The image method also used to analyze the ground effect. It is found that vortex lines separated from lifting surfaces represent the separated flows successfully. Although the present method is applied for the rectangular wing and delta wing, extensions can be possible for the arbitrary lifting surfaces. The Present results show good agreement with experimental data.