Unsteady Aerodynamic Modeling of Aircraft Response to Atmospheric Turbulence PDF Download
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Author: Jilu Li
Publisher:
ISBN:
Category :
Languages : en
Pages : 118
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Book Description
Author: Jilu Li
Publisher:
ISBN:
Category :
Languages : en
Pages : 118
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 17
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Author: Pau Castells Marin
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
The prediction of the aircraft response to gust and turbulence is of major importance for different purposes. Gust load analysis is an essential part of aircraft design and certification. The effect of gust and turbulence on aircraft flight dynamics is also of interest. Models able to capture relevant effects at these conditions in early design phases are essential in order to anticipate and assess the aircraft response and flight control laws in realistic atmospheric disturbances before flight test. This work proposes a modelling strategy to capture relevant physics when simulating the aircraft response to gust and turbulence for flight dynamics investigations. The model provides accuracy at a low computational cost as well as consistency with gust loads analysis enabling multidisciplinary design. The approach is based on the integration of a nonlinear quasi-steady flexible flight dynamics model with an unsteady aeroelastic model linearized around a nonlinear steady state. The gust-induced forces have a significant impact on aircraft flight dynamics. Low computing times are required to cover several flight conditions and aircraft parameters. A computationally efficient multipoint aerodynamic model, which captures both unsteady aerodynamic and gust propagation effects, is generated from linearized Computational Fluid Dynamics (CFD) simulations in the frequency domain. The model is identified through a rational function approximation allowing for time domain simulations. A reduced number of additional aerodynamic states is sufficient to capture the main effects at low frequencies for flight dynamics analysis. The impact of dynamic flexibility on the response is also evaluated. Only the most energetic flexible modes are retained to reduce the number of states and ensure a low computation time. The approach is applied to simulate the vertical and lateral response of a passenger aircraft to theoretical disturbance profiles as well as realistic atmospheric turbulence at different flight conditions. Aerodynamic nonlinear effects, such as local stalls due to shock motion, in transonic conditions may appear. The linearized model is able to capture the global aircraft response at these conditions with low amplitude shock motions. Results are compared and validated with a CFD simulation based approach, coupled with a structural dynamics and flight mechanics solver. Measures from flight test are also used to assess the modelling approach. The effect of uncertainties on the response is analysed, in terms of the turbulence variation along the wingspan. Simulation results show that relevant aerodynamic effects due to gust and turbulence are captured in the frequency range of interest for flight dynamics investigations.
Author: Ellwood L. Peele
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 52
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A method is presented for estimating some lateral and longitudinal rigid-body responses of airplanes to random atmospheric turbulence. Estimates of center-of-gravity load factors and motion responses can be made simply and easily through the use of parametric charts. Sample calculations are included to illustrate the method.
Author: J.M.H. Dunn
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Elijah W. Turner
Publisher:
ISBN:
Category : Atmospheric turbulence
Languages : en
Pages : 150
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 30
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Author: J. C. van der Vaart
Publisher:
ISBN:
Category :
Languages : en
Pages : 11
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Book Description
Results of a theoretical study on the effects of unsteady aerodynamics on symmetric aircraft responses due to elevator and vertical turbulence inputs, are presented. Several linear models were developed to describe unsteady lift and downwash and delays due to horizontal tail length. Results for three example aircraft types show that calculated normal acceleration levels due to turbulence are very 'little affected by including unsteady wing lift and downwash. However, there appears to be a noticable influence on plunging acceleration and pitch rate response to elevator or vertical turbulence inputs.
Author: Elijah William Turner
Publisher:
ISBN:
Category : Aeronautics in meteorology
Languages : en
Pages : 60
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Book Description
The traditional power spectral density design procedure is reviewed. The evolution of modeling atmospheric turbulence is traced from the discrete gust to the present continuous representation. The modeling of an aircraft structure as a lumped parameter linear system excited by oscillatory air forces is outlined, and solutions to the resulting equations of motion are indicated. Expressions for the number of exceedances of specified load levels are presented and compared for stationary Gaussian turbulence and for stationary Gaussian patch turbulence. The motivation for modeling atmospheric turbulence as a nonstationary process is addressed, and several models for nonstationary turbulence are reviewed.
Author: Frederick O. Smetana
Publisher:
ISBN:
Category : Gust loads
Languages : en
Pages : 60
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Book Description
