Transport Wing Flutter Model Transonic Limit Cycle Oscillation Test

Edwards, John W.; Spain, C. Victor; Keller, Donald F.; Moses, Robert W.; Schuster, David M.

doi:10.2514/1.30079

Cited by 13 publications

(16 citation statements)

References 9 publications

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“…During transonic wind tunnel tests of the HSCT wing [4], a region of "increased response" in the first bending mode was noted, and a narrow "chimney" of LCO-type flutter was observed around Mach 1. Similar narrow regions of natural mode instabilities in 1B, 1T, and 2B were also observed during wind tunnel testing of the MAVRICK wing [14]. Strictly speaking, no "pure" SDOF flutter instabilities are possible in 3D, because aeroelastic deformations will alter the flutter mode slightly, and the flutter will therefore not be SDOF flutter as in the 2D typical section case.…”

Section: B Natural Mode Instabilities and Chimneyssupporting

confidence: 63%

“…This type of model construction was used in several early studies of transonic flutter at NASA Langley, such as the study of the effect of wing thickness on the transonic flutter boundary, by Doggett, et al [13]. It was also used more recently in the MAVRIC flutter model tested by Edwards, et al [14].…”

Section: B Nonlinear Aeroelastic Modeling and Simulationmentioning

confidence: 99%

“…Institute of Aeronautics and Astronautics "bursting" or "pseudorandom", as described by Edwards, et al, in the tests of the MAVRIC wing [14]. In fact, because of the strong sensitivity of the natural mode instabilities to small changes in Mach number in the chimney, a highly nonstationary response would be expected under actual test conditions.…”

Section: B Natural Mode Instabilities and Chimneysmentioning

confidence: 99%

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Transonic Flutter Characteristics of Advanced Fighter Wings

Bendiksen

2015

56th AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

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A study of the flutter characteristics of three different wing planforms representative of present and future generations of fighters is presented. The main objective is to obtain a better understanding of complex transonic flutter behaviors involving LCOs triggered by natural mode instabilities at low dynamic pressures, followed by transitions to strong bending-torsion or multi-mode flutter at higher dynamic pressures. Two of the wings have flutter boundaries with deep "chimneys" in the vicinity of Mach 1. Inside the chimneys, the LCO amplitudes are insensitive to dynamic pressure or density and persist down to very low densities representative of altitudes in the high stratosphere. The Mach number freeze or transonic stabilization phenomenon plays an important role in determining the shape of the SDOF and chimney regions. Near the freeze Mach number, the unsteady aerodynamic forces show rapid reversals in amplitude and phase, which have a profound influence on the flutter boundary and the observed flutter characteristics. The transonic stabilization mechanism appears responsible for the rapid quenching of natural mode LCOs and the creation of deep chimneys in the flutter boundary near Mach 1, as observed in several wind tunnel tests. NomenclatureA = wing aspect ratio a = speed of sound c = airfoil or wing chord = total energy (structure) = T + U M = Mach number m = mass per unit span p = pressure t = time T = kinetic energy = shock location on upper and lower wing surface, respectively, normalized w.r.t local chord U = strain energy = freestream velocity at upstream infinity = total aerodynamic work done on wing = angle of attack = wing thickness to chord ratio  = ratio of specific heats = = relative span = wing elastic twist; also temperature ratio = taper ratio  = sweep angle  = density = transonic similarity parameter = nondimensional time  = circular frequency, rad/s  1T = frequency of first torsion mode in vacuum Subscripts LE, TE = leading and trailing edge, respectively r = wing root = conditions at upstream infinity 1 Professor, Department of Mechanical and Aerospace Engineering.

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Section: B Natural Mode Instabilities and Chimneyssupporting

confidence: 63%

Section: B Nonlinear Aeroelastic Modeling and Simulationmentioning

confidence: 99%

Section: B Natural Mode Instabilities and Chimneysmentioning

confidence: 99%

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Transonic Flutter Characteristics of Advanced Fighter Wings

Bendiksen

2015

56th AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

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“…The winglet was then mounted on a shake table, which was driven by a sinusoidal signal with variable amplitude and at frequencies within the range of 9 to 13 Hz to match the flutter frequencies of the GTW [24]. The amplitude was varied manually so that the relative displacement of the mass remained around 1 to 2 mm.…”

Section: B Winglet and Nonlinear Energy Sinkmentioning

confidence: 99%

Targeted Energy Transfer Between a Swept Wing and Winglet-Housed Nonlinear Energy Sink

et al. 2014

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A prototype nonlinear energy sink, whose design is based upon parameters determined to effectively suppress transonic aeroelastic instabilities of a wind-tunnel wing model (denoted as generic transport wing) via passive targeted energy transfer, is introduced. The lightweight nonlinear energy sink is mounted within a low-profile winglet, which is attached to the tip of the generic transport wing. In addition, safety features and measurement hardware have been built in to the prototype to facilitate a future transonic wind-tunnel experiment. The effects of the nonlinear energy sink on the structural dynamics of the model wing are demonstrated in ground vibration tests, both experimental and computational. Results show that the nonlinear energy sink causes a significant increase in the dissipation rate of energy in the second bending mode of the generic transport wing, even for small wing-tip oscillations. This is a strong indication that the prototype nonlinear energy sink will be effective in wind-tunnel tests because the frequency of the second bending mode is within the range of experimental and computational flutter frequencies of the generic transport wing. Furthermore, accompanying computational analysis is used to show that moderate friction damping in the nonlinear energy sink is unlikely to have a significant effect on the qualitative interaction between the nonlinear energy sink and the generic transport wing. Nomenclature c = nonlinear energy sink viscous damping coefficient E = energy in reduced-order system E j = energy of jth mode E 2;max = maximum energy in the second mode during a response E nes ,Ê nes = nonlinear energy sink energy in the complete and reduced-order systems F ext t = external force vector f nes , F nes = nonlinear energy sink coupling forces and vector of coupling forceŝ f nes = conservative nonlinear energy sink coupling force in reduced system I y r = component of winglet mass moment of inertia applied at the rth wing-tip node k i = nonlinear energy sink polynomial stiffness coefficients k lin , k nl = experimental linear nonlinear stiffness coefficients of nonlinear energy sink l = distance between wing-tip finite-element nodes M r = component of winglet mass applied at the rth wingtip node m = nonlinear energy sink mass M, C, K = mass, damping, and stiffness matrices of wing P = wing-tip location at which the nonlinear energy sink is coupled t = time t max = time at which energy is maximum u = nonlinear energy sink displacement relative to wing tip (y − w) w = wing-tip heave at P x = vector of finite-element wing displacements y = nonlinear energy sink displacement α = exponent of experimental nonlinear stiffness term β = mode-shape rescaling parameter E = normalized second mode energy η j , η = jth modal displacement and modal displacement vector μN = friction force ξ = physical displacement at P due to mode 2 τ = t − t max ϕ j , Φ = jth mass-orthonormalized mode-shape vector and mode-shape matrix ω j = jth modal frequency, rad∕s ζ j = jth modal damping ratio Subscript p = hea...

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“…For instance, dynamics of this sort were reported in the transonic aereolastic test of a transport wing. 5 Apart from random excitations from tunnel turbulence, one can identify different types of variability such as bursting, limit cycle oscillation (LCO) and beating responses. 5 Transonic conditions add to these sources of variability by the appearance of flowfield shocks and shock separation.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Limit Cycle Oscillation Data from the Aeroelastic Test of the SUGAR Truss-Braced Wing Model

Bartels

Funk

Scott

2015

33rd AIAA Applied Aerodynamics Conference

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Research focus in recent years has been given to the design of aircraft that provide significant reductions in emissions, noise and fuel usage. Increases in fuel efficiency have also generally been attended by overall increased wing flexibility. The truss-braced wing (TBW) configuration has been forwarded as one that increases fuel efficiency. The Boeing company recently tested the Subsonic Ultra Green Aircraft Research (SUGAR) Truss-Braced Wing (TBW) wind-tunnel model in the NASA Langley Research Center Transonic Dynamics Tunnel (TDT). This test resulted in a wealth of accelerometer data. Other publications have presented details of the construction of that model, the test itself, and a few of the results of the test. This paper aims to provide a much more detailed look at what the accelerometer data says about the onset of aeroelastic instability, usually known as flutter onset. Every flight vehicle has a location in the flight envelope of flutter onset, and the TBW vehicle is not different. For the TBW model test, the flutter onset generally occured at the conditions that the Boeing company analysis said it should. What was not known until the test is that, over a large area of the Mach number dynamic pressure map, the model displayed wing/engine nacelle aeroelastic limit cycle oscillation (LCO). This paper dissects that LCO data in order to provide additional insights into the aeroelastic behavior of the model.

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Transport Wing Flutter Model Transonic Limit Cycle Oscillation Test

Cited by 13 publications

References 9 publications

Transonic Flutter Characteristics of Advanced Fighter Wings

Transonic Flutter Characteristics of Advanced Fighter Wings

Targeted Energy Transfer Between a Swept Wing and Winglet-Housed Nonlinear Energy Sink

Analysis of Limit Cycle Oscillation Data from the Aeroelastic Test of the SUGAR Truss-Braced Wing Model

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