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AEROELASTIC EFFECTS OF SPOILER SURFACES ON A LOW-ASPECT-RATIO rectangular wing

JOURNAL OF AIRCRAFT 1992年第5期29卷 768-773页

作者： COLE, SR NASA Langley Research Center Hampton Virginia 23665

An experimental research study to determine the effectiveness of spoiler surfaces in suppressing flutter onset for a low-aspect-ratio, rectangular wing has been conducted in the Langley Transonic Dynamics Tunnel (TDT). The wing model used in this flutter test consisted of a rigid wing mounted to the wind-tunnel wall by a flexible, rectangular beam. The flexible beam was connected to the wing root and cantilever mounted to the wind-tunnel wall. The wing had a 1.5 aspect ratio based on wing semispan and a NACA 64A010 airfoil shape. The spoiler surfaces consisted of thin, rectangular aluminum plates that were vertically mounted to the wing surface. The spoiler surface geometry and location on the wing surface were varied to determine the effects of these parameters on the classical flutter of the wing model. Subsonically, the experiment showed that spoiler surfaces increased the flutter dynamic pressure with each successive increase in spoiler height or width. This subsonic increase in flutter dynamic pressure was approximately 15% for the maximum height spoiler configuration and for the maximum width spoiler configuration. At transonic Mach numbers, the flutter dynamic pressure conditions were increased even more substantially than at subsonic Mach numbers for some of the smaller spoiler surfaces. But for larger spoiler sizes (in terms of either height or width) the spoilers forced a torsional instability in the transonic regime that was highly Mach number dependent. This detrimental torsional instability was found at dynamic pressures well below the expected flutter conditions. Variations in the spanwise location of the spoiler surfaces on the wing showed little effect on flutter. Flutter analysis was conducted for the basic configuration (clean wing with all spoiler surface mass properties included). The analysis correlated well with the clean wing experimental flutter results.

关键词： rectangular wing Aspect Ratio Spoilers Aerodynamic Force Stagnation Pressure Strouhal Numbers Wind Tunnel Models wing Root Structural Dynamics NACA 64A010

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VISCOUS SUPERSONIC-FLOW COMPUTATIONS OVER A DELTA-rectangular wing WITH SLANTING SURFACES

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JOURNAL OF SPACECRAFT AND ROCKETS 1992年第2期29卷 159-165页

作者： CHAN, JS BOEING AEROSP & ELECTR SEATTLEWA 98124

A three-dimensional Navier-Stokes code has been applied to calculate flowfields over sharp-edged delta-rectangular wing with slanting surfaces at supersonic conditions. The steady-state solutions were obtained by solving the full compressible Reynolds-averaged Navier-Stokes equations on a three-dimensional multizone grid using the MacCormack finite-volume explicit algorithm and the Baldwin-Lomax turbulence model. The computations were carried out at a fixed freestream Mach number and at various angles of attack. Grid resolution effects were also investigated. The numerical computations were found to agree well with the experimental data.

关键词： rectangular wing Supersonic Viscous Flow Aerodynamic Performance Reynolds Averaged Navier Stokes Aerodynamic Characteristics Baldwin Lomax Turbulence Model Vortex Breakdown Wind Tunnel Tests Turbulent Boundary Layer Thermal Conductivity

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LIFT RESPONSE OF A rectangular wing UNDERGOING A STEP CHANGE IN FORWARD SPEED

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AIAA JOURNAL 1990年第7期28卷 1306-1307页

作者： SAWYER, RS SULLIVAN, JP Purdue University West Lafayette Indiana 47906

The result presented showed the response of an aspect ratio 4 rectangular wing to a rapid acceleration to a constant speed. The wing showed the correct steady-state lift, and when the result was filtered to eliminate unwanted noise, it was matched nearly perfectly by the step response for an aspect ratio 4 wing treated by the same filter. The finite size and influence of the rectangular wing wake then is correctly accounted for by theory. This finding is extremely important since an old analysis has finally been verified by experiment.

关键词： rectangular wing Aspect Ratio Lift Coefficient Data Acquisition Aerodynamic Force Oscilloscope Photodiodes Vorticity Vortices

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Inverse aeroacoustic problem for a rectangular wing

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AIAA JOURNAL 2000年第2期38卷 203-210页

作者： Wood, TH Grace, SM Boston Univ Dept Aerosp & Mech Engn Boston MA 02215 USA

An investigation is made of the feasibility of aeroacoustic inversion, where the pressure on a thin, flat, rigid rectangular wing undergoing rigid oscillations or interacting with unsteady, subsonic flow is to be predicted from the far-field acoustic signal. This problem is ill-posed because small pressure fluctuations in the far field are larger in the near field by a factor equal to the reciprocal of the distance from the wing. In the inverse model, this ill-posedness manifests itself in the kernel of a two-dimensional Fredholm integral equation of the first kind. Discretization of this integral equation using a physically meaningful collocation series results in an ill-conditioned system of equations which is solved using the singular value decomposition (SVD). The SVD generally requires regularization techniques to discard redundant or unphysical information. An algorithm is developed for optimally determining the near-field pressure without relying on a user-specified regularization parameter. Tests using numerically generated input data show the inversion is feasible and accurate for accurate input data, The inversion remains feasible when errors are introduced in the far-field measurements and the measurable parameters of the flow.

关键词： rectangular wing Singular Value Decomposition Freestream Mach Number Aspect Ratio Inverse Problems Sensitivity Analysis Acoustic Measurement Collocation Method Aeroacoustics Freestream Turbulence

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Drag evolution of a rectangular wing with triggered wing-tip separation

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JOURNAL OF AIRCRAFT 2005年第5期42卷 1369-1371页

作者： Ardonceau, PL Trapier, S Ecole Natl Super Mecan & Aerotech LEA F-86961 Chasseneuil France Off Natl Etud & Rech Aerosp F-92322 Chatillon France

A numerical study of the efficiency of a rectangular planar wing, in subsonicviscous or inviscid flow, shows a sensitivity of the lift and drag to the vortical flow separationpattern over the wing tips. A narrow strip, added to trigger the separation over a classical tip,reduces the drag at constant lift of approximately 1% at C_L = 0.56 for a wing of aspect ratio *** effect is associated to the modification of the pressure field over the wing tip, where afavorable pressure differential appears, increasing the lift without a balanced increase of thedrag. From a different point of view, an earlier separation over the tip produces a wider vorticalwake, therefore enhancing the effective span of the wing. The length of the strip should not exceed90% of the tip chord, its trailing edge being located at the trailing edge of the wing. Technicallysuch a device could be added without much difficulty on wing tips with backward-facing fairings.

关键词： wing Tip rectangular wing Aspect Ratio Lift Induced Drag Aerodynamic Efficiency Aeroplane Separated Flows Finite Volume Method Lifting wing Vortices

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Derived Properties of rectangular wing Based on Eigenstructure of Lifting Line Theory

Derived Properties of Rectangular Wing Based on Eigenstructu...

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AIAA Aviation Forum

作者： Yukish, Michael A. Valenti, Justin D. Penn State Univ Dept Aerosp Engn University Pk PA 16803 USA

ISBN: (数字)9781624105982

ISBN: (纸本)9781624105982

At the heart of many numerical implementations of lifting line theory (LLT) is the matrix relating vortex strength to downwash. This type of matrix is a symmetric Toeplitz matrix which has well-studied properties, including recent research that has developed methods to identify the asymptotics of individual eigenvalues and eigenvectors of infinite Toeplitz matrices. This paper explores applying the method to the lifting line matrix to identify its eigenstructure, and demonstrates using them to develop an accurate estimate of the coefficients of lift and induced drag of a rectangular wing.

关键词： rectangular wing Free Stream Velocity Horseshoe Vortex Lift Coefficient Aspect Ratio Aerospace Engineering

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Performance effects of winglets with leading edge protuberances on a rectangular wing

Performance effects of winglets with leading edge protuberan...

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AIAA Science and Technology Forum and Exposition (AIAA SciTech Forum)

作者： Flores-Mezarina, Juan A. Bravo-Mosquera, Pedro D. Ribeiro, Daniel G. Ceron-Munoz, Hernan D. Univ Sao Paulo Sao Carlos Sch Engn Dept Aeronaut Engn BR-13563120 Sao Carlos SP Brazil

ISBN: (数字)9781624106095

ISBN: (纸本)9781624106095

The leading edge protuberances are inspired on the humpback whale pectoral flippers. They act as control flow devices that reduce the flow three dimensional effects on wings and increase their aerodynamic performance at high angles of attack. Although there is plenty research about their dynamics, research on their possible applications is still in emerging phase. In this study, their effects on a winglet performance are assessed. A rectangular wing, a smooth leading edge winglet and three winglets with different leading edge protuberances sizes were designed and 3D printed to carry out CFD simulations, wind tunnel measurements and flow visualization tests. It was shown that the winglets with leading edge protuberances perform similarly to the base one in terms of lift at most angles of attack. In terms of drag, the winglet with the largest protuberances reduced parasite drag while the other two slightly increased it. On the other hand, all of them reduced the induced drag slope inversely proportional to their protuberances' size. Thus, the winglet with the largest protuberances had a significant aerodynamic efficiency improvement at low angles of attack. The CFD velocity curl contours downstream the wing showed that it also reduced the wing tip vortices' intensity. The leading edge protuberances showed the potential to enhance the winglet's performance on a rectangular wing.

关键词： rectangular wing Aircraft Configurations Aerodynamic Performance Aerodynamic Coefficients wingtip Vortices Wind Tunnel Tests Flow Visualization Techniques Numerical Simulation wingtip Device Aspect Ratio

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TRANSONIC PRESSURE DISTRIBUTIONS ON A rectangular SUPERCRITICAL wing OSCILLATING IN PITCH

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JOURNAL OF AIRCRAFT 1984年第8期21卷 576-582页

作者： RICKETTS, RH SANDFORD, MC SEIDEL, DA WATSON, JJ NASA Langley Research Center Hampton Virginia

The purpose of the wind-tunnel test was to measure data for use in the development and assessment of transonic analytical codes. The effects on the wing pressure distribution of Mach number, mean angle of attack, and oscillation frequency and amplitude were measured. Results from the XTRAN3S program (a nonlinear transonic small disturbance code) and from the RHOIV program (a linear lifting surface kernel function code) were compared to data measured for a Mach number of 0. 7 and for oscillation frequencies ranging from 0 to 20 Hz. The XTRAN3S steady and unsteady results agreed fairly well with the measured data. The RHOIV unsteady-result agreement was fair but, of course, did not predict shock effects.

关键词： Lift Coefficient Freestream Mach Number Pressure Coefficient Supercritical Airfoils Data Acquisition System rectangular wing wing Root National Aerospace Laboratories Langley Transonic Dynamics Tunnel Supercritical Flow

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Unsteady Ground Effects On A rectangular And Swept wing Undergoing Heaving And Pitching During Deceleration

Unsteady Ground Effects On A Rectangular And Swept Wing Unde...

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AIAA Science and Technology Forum and Exposition (AIAA SciTech)

作者： Adhikari, Dibya Raj Loubimov, George Bhattacharya, Samik Kinzel, Michael P. Univ Cent Florida Dept Mech & Aerosp Engn Orlando FL 32826 USA

ISBN: (数字)9781624105951

ISBN: (纸本)9781624105951

An experimental study, validated by numerical simulation, has been performed to understand the aerodynamic characteristics of a rectangular and swept wing in ground effect. Here, we consider gradual deceleration to stop from a steady velocity with decreasing ground height applicable to a landing situation. The wing also undergoes a heaving and pitching motion during deceleration. We extend our results at two different initial angles of attack i.e. alpha(0) = 15 and 45. During the heaving motion, the lift and drag forces increase to an initial peak force from the initial force value;this can be attributed to the change in effective angle of attack caused by changes in relative velocity. The initial peak force is even higher in the heaving and pitching motion case;however, in the later stages of this configuration, the aerodynamic forces drop rapidly. At the end of the motion, the leading edge vortex (LEV) on the heaving wing planform is large compared to the heaving and pitching wing planform. The rapid decrease in the lift force on the heaving and pitching wing planform is correlated to the detachment of the LEV and trailing edge vortex (TEV) from the wing surface. In the steady phase, the swept wing produced a relatively higher value of the forces compared to the rectangular wing planform. However, during the growth phase, the forces overlap between both the planform shapes. The fluid physics are explored and discussed in this study.

关键词： rectangular wing High Aspect Ratio Aerodynamic Performance Aerodynamic Characteristics Vortex Shedding Numerical Simulation Oscillating Motions Velocity Profiles Numerical Modeling Cambered Airfoil

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Influence of wingspan on aerodynamic properties of rectangular NACA4412 wing in ground effect

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JOURNAL OF THE BRAZILIAN SOCIETY OF MECHANICAL SCIENCES AND ENGINEERING 2024年第2期46卷 1-15页

作者： Hu, Huan Zhang, Guiyong Shi, Yajun Zhang, Zhifan Sun, Tiezhi Zong, Zhi Dalian Univ Technol Sch Naval Architecture Engn State Key Lab Struct Anal Ind Equipment Dalian 116024 Peoples R China Collaborat Innovat Ctr Adv ship & Deep Sea Explora Shanghai 200240 Peoples R China China Ship Sci Res Ctr Wuxi 200136 Peoples R China

For wing-in- ground vehicles, ground effect increases lift force, which is mostly affected by wingspan. Four rectangular NACA4412 wings with varied aspect ratios were chosen to explore the influence of wingspan on aerodynamic properties in ground effect, and their aerodynamics were studied using CFD modeling. To simulate the flow around the wing in ground effect, SST k- omega model was utilized. The overset technique was used to achieve varied pitch angle and altitude states where the wing operates. Results demonstrate that as wingspan increases, the variation rate of lift coefficient with respect to pitch angle or altitude increases, especially when pitch angle is less than 2 degrees and relative altitude is less than 0.3. While a smaller wingspan causes a greater varying rate of downwash angle with pitch angle or altitude, when a wing has a smaller span and its relative altitude is less than 0.3, the development of the wingtip vortex becomes a stronger restriction for the block of ground, significantly reducing the downwash angle. The distance between the aerodynamic centers of altitude and pitch angle decreases as the wingspan expands, and the maximum magnitudes of change in chord length reach 0.045 and 0.2749 of chord length when the aspect ratio shifts from 1 to 4. The aspect ratio has no discernible effect on the boundary of static stability. When the aspect ratio increases from 1 to 4, the center of gravity must be moved upstream to ensure motion stability, and the maximum distance is 0.098 of the chord length.

关键词： Ground effect rectangular wing Aspect ratio Downwash angle Static and dynamic stability

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