Quasi-steady doublet-lattice correction for aerodynamic gust response prediction in attached and separated transonic flow

Friedewald, Diliana; Thormann, Reik; Kaiser, Christoph; Nitzsche, Jens

doi:10.1007/s13272-017-0273-0

Cited by 11 publications

(6 citation statements)

References 21 publications

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“…The existence of dynamic overshoots in transonic flow, however, is not well investigated and one of the early dynamic stall publications is even questioning their existence [42]. An evidence of transonic dynamic overshoots can be found in [23] for a clean wing configuration under gust excitation and can also be confirmed by the findings in this study. Mainly low excitation frequencies and large amplitudes lead to an overshoot of the static maximum value, independently of the Mach number, see Figures 10 and 11.…”

Section: Maximum Lift Coefficientsupporting

confidence: 79%

“…Mallik and Raveh [22] suggest that this trend is also present for purely aerodynamic responses of an airfoil. Observations in the frequency-domain reveal that an increase of the gust amplitude leads to smaller response derivatives at lower excitation frequencies, and larger response derivatives at higher frequencies [23]. This study also shows that long '1-cos' gusts are more affected by amplitude effects than shorter gusts, which is in agreement with [22].…”

Section: Introductionsupporting

confidence: 82%

“…After 1983, additional physical insight on transonic unsteady nonlinear effects was gained only in the last decade [9,12,[20][21][22][23], with increasing computational power and growing trust in RANS-based methods for separated flows. Most studies analyze complex three-dimensional, aeroelastically-coupled configurations encountering '1-cos' gusts since these broadband excitations are demanded by the Certification Specifications [24].…”

Section: Introductionmentioning

confidence: 99%

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Numerical Simulations on Unsteady Nonlinear Transonic Airfoil Flow

Friedewald

2020

Aerospace

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Large-amplitude excitations need to be considered for gust load analyses of transport aircraft in cruise flight conditions. Nonlinear amplitude effects in transonic flow are, however, only marginally taken into account. The present work aims at closing this gap by means of systematic unsteady Reynolds-averaged Navier-Stokes simulations. The RAE2822 airfoil is analyzed for a variety of sinusoidal gust excitations at different transonic Mach numbers. Responses are evaluated with respect to lift and moment coefficients, their derivatives and the unsteady shock motion. A strong dependency on inflow Mach number and excitation frequency is observed. Generally, amplitude effects decrease with lower Mach numbers or higher excitation frequencies. The unsteady nonlinear simulations predict lower maximum lift values and lower lift and moment derivatives compared to their linear counterparts for lower frequencies in combination with large-amplitude excitations. For the mid-frequency range, trends are not as clear. Additionally, it is shown that the variables of harmonic distortion and maximum shock motion might not be reasonable indicators to predict a nonlinear response.

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Section: Maximum Lift Coefficientsupporting

confidence: 79%

Section: Introductionsupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

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Numerical Simulations on Unsteady Nonlinear Transonic Airfoil Flow

Friedewald

2020

Aerospace

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“…Під час визначення розподілу аеродинамічних сил та моментів по поверхні ЛА обтікання приймають квазістаціонарним [2,3] або нестаціонарним [4,5]. У першому випадку не враховується передісторія руху, а лише розподіл кутів атаки на даний момент часу.…”

Section: вступunclassified

Influence of flight mode on loads from turbulent air

Hevko¹,

Bondar²

2022

MGS

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This paper investigated the influence of altitude and flight speed on the loads arising on the elastic wing of a turbojet aircraft of conventional layout, which falls into turbulent conditions. The aircraft structure is modeled by elastic beams with appropriate weight and stiffness distribution. Performed a modal analysis of the aircraft design and examined the influence of the number of calculated tones own oscillations on the loading of an aircraft wing. Aerodynamic forces and moments are determined by the dipole lattice and constant pressure method (DLM/CPM). Non-stationary characteristics are also taken into account, as required by certification specification. Determining the effect of flight speed showed the need to consider both the minimum and maximum speeds, because at minimum speed the end zone of the wing is loaded more, and at the cruise speed ‒ the root section. When analyzing the effect of flight altitude on the load, determined that the maximum values of transverse force and bending moment occur when flying at minimum altitude, and the torque on the wing reaches the maximum value at altitudes with the maximum Mach number. Separately highlighted loads of aircraft wing at horizontal balanced flight. Also showed that the speed of flight, namely the Mach number, significantly affects the torque that occurs on the wing.

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“…The dependence of the finite poles with the indices ij in N c,ij and p k,ij refers to the fact that each component of the transfer function matrix H (ω) is dealt with separately. Note that, compared to the classical least-squares fit of the RFA technique which uses real coefficients [3,4,14], Equation 16is able to represent peaks of the aerodynamic transfer functions in the frequency domain which appear in the transonic flow regime [49] by the presence of conjugate pair poles [6]. Additionally, the fit of Equation (16) does not suffer the ill-conditioning present when using an increasing number of real poles.…”

Section: Generalized Realization Of the Aerodynamic Systemmentioning

confidence: 99%

A Generalized State-Space Aeroservoelastic Model Based on Tangential Interpolation

2019

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In this work, a new approach for the generation of a generalized state-space aeroservoelastic model based on tangential interpolation is presented. The resulting system of differential algebraic equations (DAE) is reduced to a set of ordinary differential equations (ODE) by residualization of the non-proper part of the transfer function matrix. The generalized state-space is of minimal order and allows for the application of the force summation method (FSM) for the aircraft loads recovery. Compared to the classical rational function approximation (RFA) approach, the presented method provides a minimal order realization with exact interpolation of the unsteady aerodynamic forces in tangential directions, avoiding any selection of poles (lag states). The new approach is applied first for the generation of an aerodynamic model for the bidimensional unsteady incompressible flow in the time domain. Next, an application on the generation of an aeroservoelastic model for loads evaluation of the flutter reduced order assessment (FERMAT) model under atmospheric disturbances is done, showing an excellent agreement with the reference model in the frequency domain. The proposed aeroservoelastic model of minimal order is suited for loads analysis and multivariable control design, and an application to a gust loads alleviation (GLA) strategy is shown.

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Quasi-steady doublet-lattice correction for aerodynamic gust response prediction in attached and separated transonic flow

Cited by 11 publications

References 21 publications

Numerical Simulations on Unsteady Nonlinear Transonic Airfoil Flow

Numerical Simulations on Unsteady Nonlinear Transonic Airfoil Flow

Influence of flight mode on loads from turbulent air

A Generalized State-Space Aeroservoelastic Model Based on Tangential Interpolation

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