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EFFECT OF wing TIP STRAKES ON wing LIFT-DRAG RATIO

JOURNAL OF AIRCRAFT 1989年第5期26卷 410-416页

作者： MA, EC Beijing Institute of Aeronautics and Astronautics Beijing China

The objective is to increase the wing lift-drag ratio by vortex induction method generated with wing tip strakes. Experimental results for a rectangular wing of aspect ratio 5 equipped with wing tip strakes indicated that the flat-plate strake was worse than a strake with dihedral angle and thickness for increasing the wing liftdrag ratio. Strakes cut off at 45 deg were the best at increasing the wing lift-drag ratio, while strakes with δ = 0 deg were the best at improving the ratio. Also, the experimental results for rectangular wings of aspect ratios 5 and 2 equipped with wing tip strakes, relative to the equivalent simple wings (i.e., the spanwise length of strakes have been calculated into a simple wing aspect ratio), demonstrated that, for C_L =0.3-0.9, 002DK/K was 7-14.4% for wings of A =5 and 9-26.6% for wings of A = 2. The addition of strakes is beneficial for any aspect ratio at any speed (or C_L) up to high subsonic speeds. © 1987 American Institute of Aeronautics and Astronautics, Inc.

关键词： rectangular wing wing Root winglets Aspect Ratio Vortices Subsonic Speed Aeroplane Lift Coefficient Aerodynamic Characteristics Tapered wings

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AEROELASTIC STABILITY CHARACTERISTICS OF A COMPOSITE SWEPT wing WITH TIP WEIGHTS FOR AN UNRESTRAINED VEHICLE

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JOURNAL OF AIRCRAFT 1987年第11期24卷 793-802页

作者： LOTTATI, I Technion—Israel Institute of Technology Haifa Israel

An analytical investigation to determine aeroelastic flutter and divergence behavior of a composite, forwardswept rectangular wing was conducted. It is assumed that the wing is carrying a fuselage at its semispan, a pylon at the wing tip, and that the aircraft is in a free-flight condition (unrestrained vehicle). The influence, due to the variation in the bending-torsion stiffness coupling of the tailored wing on the flutter and divergence critical dynamic pressure, is analyzed. The paper discusses the influence of the warping effect on the system’s flutter and divergence velocities. The aeroelastic stability behavior of the system is obtained by applying an optimization procedure that solves exactly the coupled bending-torsion equations of motion for the unrestrained swept-wing aircraft. The results of the present study indicate that the warping effect significantly influences the system’s aeroelastic characteristics. © 1987 by I. Lottati. Published by the American Institute of Aeronautics and Astronautics, Inc.

关键词： Aeroelastic Stability rectangular wing Fuselages wing Tip Dynamic Pressure Forward Swept wing Aerodynamic Moments Airspeed Composite Aircraft High Aspect Ratio

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ACT WIND-TUNNEL EXPERIMENTS OF A TRANSPORT-TYPE wing

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JOURNAL OF AIRCRAFT 1991年第2期28卷 139-145页

作者： UEDA, T MATSUSHITA, H SUZUKI, S MIYAZAWA, Y National Aerospace Laboratory Chofu Tokyo Japan

This paper summarizes the wind-tunnel experiments on the active control technology that have been conducted in the large low-speed wind tunnel of the National Aerospace Laboratory. The experiments include a gust load alleviation (GLA) and two active flutter suppression (AFS) tests. A wind-tunnel model of the cantilevered elastic wing is designed to simulate an energy efficient transport. The model has two control surfaces, which are individually driven by small electric torque motors. In the GLA tests using the Dryden-type random gust, 25% reduction of bending moment in rms values at the wing root was attained by a single surface control. In the second AFS test, flutter boundary was raised by 13% in speeds when two control surfaces were activated simultaneously. It was found that the leading-edge control surface was effective for the AFS.

关键词： Low Speed Wind Tunnel Control Surfaces rectangular wing Aerodynamic Force Modern Control Theory Bending Moment National Aerospace Laboratories Torque Motors wing Root Mathematical Models

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Limit cycle oscillations of delta wing models in low subsonic flow

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AIAA JOURNAL 1999年第11期37卷 1355-1362页

作者： Tang, DM Henry, JK Dowell, EH Duke Univ Dept Mech Engn & Mat Sci Durham NC 27708 USA Duke Univ Sch Engn Durham NC 27708 USA

A nonlinear, aeroelastic analysis of a low-aspect delta wing modeled as a plate of constant thickness demonstrates that limit cycle oscillations (LCOs) of the order of the plate thickness are possible. The structural nonlinearity arises from double bending in both the chordwise and the spanwise directions. The results using a vortex lattice aerodynamic model for a low-Mach-number how complement earlier studies for rectangular wing platforms that showed similar qualitative results. The theoretical results for the flutter boundary (beyond which LCO occurs) have been validated by comparison to the experimental data reported by other investigators for low aspect-ratio delta wings. Also, the LCOs found experimentally by previous investigators (but not previously quantified prior to the present work) are consistent with the theoretical results reported here. Reduced-order aerodynamic and structural models are used to substantially decrease computational cost with no loss in accuracy. Without the use of reduced-order models, calculations of the LCO would be impractical. A wind-tunnel model is tested to provide a quantitative experimental correlation with the theoretical results for the LCO response itself.

关键词： rectangular wing Supersonic Flow Vortices Aspect Ratio Aerodynamic Coefficients Aeroelastic Analysis Structural Modeling Wind Tunnel Models Structural Nonlinearities Flow Velocity

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Analytic sensitivities and approximations in supersonic and subsonic wing control surface unsteady aerodynamics

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JOURNAL OF AIRCRAFT 1997年第3期34卷 370-379页

作者： Li, WL Livne, E University of Washington Seattle Washington 98195

Development of efficient, design-oriented analysis techniques and associated approximations for wing/control surface unsteady aerodynamics is crucial to the success of any multidisciplinary aeroservoelastic optimization of airplanes including active control technology, A design-oriented capability for unsteady supersonic aerodynamics for planar wing/control surface configurations is presented here, Explicit expressions for aerodynamic influence coefficients make it possible to efficiently obtain analytic sensitivities of generalized aerodynamic loads with respect to planform shape, Examination of the mathematical structure of the discretization used, similar to other aerodynamic panel methods, reveals sources of discontinuity of derivatives with respect to shape in the supersonic case, Sources of nonsmooth behavior of the unsteady aerodynamic loads in subsonic how are identified and eliminated, The accuracy and computational cost of alternative approximation techniques are studied, A second-order approximation technique based on the direct and adjoint solutions at a reference configuration is presented, Experience and insight are gained in the area of design-oriented and approximate unsteady aerodynamics, to be used in the nonlinear programming/approximation concepts approach to engineering optimization.

关键词： Unsteady Aerodynamic Analysis Aerodynamic Characteristics Aeroplane Mach Cones Nonlinear Programming rectangular wing Sensitivity Analysis Linear Time Invariant Control Surfaces MDO

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Minimum Induced Drag for Tapered wings Including Structural Constraints

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JOURNAL OF AIRCRAFT 2020年第4期57卷 782-786页

作者： Taylor, Jeffrey D. Hunsaker, Douglas F. Utah State Univ Mech & Aerosp Engn 4130 Old Main Hill Logan UT 84322 USA

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EFFECTS OF MODAL SYMMETRY ON TRANSONIC AEROELASTIC CHARACTERISTICS OF wing-BODY CONFIGURATIONS

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JOURNAL OF AIRCRAFT 1989年第3期26卷 271-280页

作者： GURUSWAMY, GP TU, EL NASA Ames Research Center Moffett Field California

To study accurately the transonic aeroelastic characteristics, it is important to model the full aircraft configuration, including asymmetry. Recently, an accurate method of computing unsteady transonic flows on full-span wing-body configurations was developed using the transonic potential flow theory. In this work, the method is further developed to account for the aeroelasticity of full-span wing-body configurations. This is accomplished by simultaneously integrating the unsteady aerodynamic forces and modal structural equations of the wing-body configurations. To validate the method, aeroelastic computations are made for a wing-body configuration with a rectangular wing. The aeroelastic responses of this configuration are correlated with the responses of a similar isolated wing. The comparisons are favorable. Aeroelastic computations associated with symmetric and antisymmetric modes are also made to study the influence of modal asymmetry on responses. This new development is further illustrated by computing the aeroelastic characteristics of a typical fighter aircraft. The results from this study will be useful in accurately computing the transonic flutter boundaries of aircraft, including those associated with asymmetric modes. © 1989 American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

关键词： wing Body Configuration Aerodynamic Force Vector Aeroelastic Stability Aircraft Configurations rectangular wing Computing Small Perturbation Flow Fighter Aircraft Finite Element Method Dynamic Pressure

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MEASURED UNSTEADY TRANSONIC AERODYNAMIC CHARACTERISTICS OF AN ELASTIC SUPERCRITICAL wing

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JOURNAL OF AIRCRAFT 1987年第4期24卷 225-230页

作者： SEIDEL, DA SANDFORD, MC ECKSTROM, CV NASA Langley Research Center Hampton Virginia

Transonic steady and unsteady aerodynamic data were measured on a large elastic wing in the NASA Langley Transonic Dynamics Tunnel. The wing had a supercritical airfoil shape and a leading-edge sweepback of 28.8 deg. The wing was heavily instrumented to measure both static and dynamic pressures and deflections. A hydraulically driven outboard control surface was oscillated to generate unsteady airloads on the wing. Representative results from the wind-tunnel tests are presented and discussed. An experimentally predicted dynamic wing instability boundary, sensitive to angle of attack, is reported. © 1987 American Institute of Aeronautics and Astronautics, Inc.

关键词： Supercritical Airfoils Aerodynamic Characteristics Angle of Attack Pressure Coefficient rectangular wing Wind Tunnel Models Langley Transonic Dynamics Tunnel Amplitude Control Bending Moment wing Root

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ANALYSIS OF ROLLED DELTA-wing FLOWS USING EFFECTIVE SWEEP AND ATTACK ANGLES

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JOURNAL OF AIRCRAFT 1995年第5期32卷 978-984页

作者： STEPHEN, EJ Frank J. Seller Research Laboratory U.S. Air Force Academy Colorado 80840-6272

Flow visualization data over the suction surface of a 65-deg swept delta wing were recorded at a 30-deg incidence angle for a range of static roll angles (-42 to 42 deg) and Reynolds number of 9.0 x 10(5). The data were reduced to provide information on the vortex relative position and the burst point location. The results were compared to previously recorded rolling moment data, to provide an understanding of the relationship between now behavior and aerodynamic loading. The combination of roll about the body axis and an axis incidence angle with the flow induced a sideslip angle relative to the wing. Combining the sideslip angle with the nominal leading-edge sweep of the wing provided an effective leading-edge sweep angle. Using the effective sweep angle, along with the previous data for unyawed delta wings, the now behavior over either side of the wing was predicted. Extending this analysis suggested the presence of nonzero trim positions in roll, based on wing movement in and out of a stalled regime. These trim positions have been recorded in free-to-roll experiments.

关键词： rectangular wing Delta wing Vortex Angle of Attack Sweep Angle Flow Visualization Sideslip Angle Aerodynamic Loads Wind Tunnels Separated Flows Image Analysis

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Measurements in the tip vortex roll-up region of an oscillating wing

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AIAA JOURNAL 2000年第6期38卷 1092-1095页

作者： Chang, JW Park, SO Korea Adv Inst Sci & Technol Dept Aerosp Engn Taejon 305701 South Korea

The tip vortex roll-up phenomena behind an oscillating rectangular wing was examined. Phase-averaged mean axial and tangential velocity profiles in the near field of the trailing vortex behind the oscillating wing were obtained. These velocity profiles demonstrate the hysteretic behavior of the wake. To adequately describe the change of circulation during a cycle of oscillation, the phase lag of the measurement signal was taken into account.

关键词： Oscillating wing Tip Vortex Angle of Attack Freestream Velocity Aspect Ratio NACA 0012 Laser Doppler Velocimetry rectangular wing Convection Vorticity Freestream Turbulence

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