Further Refinement of the Subsonic Doublet-Lattice Method

1998 ◽  
Vol 35 (5) ◽  
pp. 720-727 ◽  
Author(s):  
William P. Rodden ◽  
Paul F. Taylor ◽  
Samuel C. McIntosh
Keyword(s):  
Lattice Method ◽  
Doublet Lattice Method

Numerical Solutions of Nonsteady Two-Dimensional Transonic Flows

1979 ◽  
Vol 101 (3) ◽  
pp. 341-347 ◽  
Author(s):  
M. Couston ◽  
J. J. Angelini
Keyword(s):  
Numerical Solutions ◽  
Low Frequency ◽  
Two Dimensional ◽  
Lattice Method ◽  
Alternating Direction Implicit ◽  
Flow Problems ◽  
Present Procedure ◽  
Alternating Direction ◽  
Trailing Edge Flaps ◽  
Doublet Lattice Method

An alternating-direction implicit algorithm is applied to solve an improved formulation of the low-frequency, small-disturbance, two-dimensional potential equation. Linear solutions are presented for oscillating trailing edge flaps, plunging and pitching flat-plate airfoils, and compared with results obtained by a doublet-lattice-method. Nonlinear calculations for both steady and unsteady flow problems are then compared with results obtained by using the complete Euler equations. The present procedure allows one to solve complex aerodynamic problems, including flows with shock waves.

Modeling and Analysis of Piezoelectric Energy Harvesting From Aeroelastic Vibrations Using the Doublet-Lattice Method

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Carlos De Marqui ◽  
Wander G. R. Vieira ◽  
Alper Erturk ◽  
Daniel J. Inman
Keyword(s):  
Energy Source ◽  
Energy Harvesting ◽  
Frequency Domain ◽  
Electromechanical Coupling ◽  
Lattice Method ◽  
Modeling And Analysis ◽  
Piezoelectric Energy ◽  
Doublet Lattice Method ◽  
Aeroelastic Vibrations ◽  
Air Vehicles

Multifunctional structures are pointed out as an important technology for the design of aircraft with volume, mass, and energy source limitations such as unmanned air vehicles (UAVs) and micro air vehicles (MAVs). In addition to its primary function of bearing aerodynamic loads, the wing/spar structure of an UAV or a MAV with embedded piezoceramics can provide an extra electrical energy source based on the concept of vibration energy harvesting to power small and wireless electronic components. Aeroelastic vibrations of a lifting surface can be converted into electricity using piezoelectric transduction. In this paper, frequency-domain piezoaeroelastic modeling and analysis of a cantilevered platelike wing with embedded piezoceramics is presented for energy harvesting. The electromechanical finite-element plate model is based on the thin-plate (Kirchhoff) assumptions while the unsteady aerodynamic model uses the doublet-lattice method. The electromechanical and aerodynamic models are combined to obtain the piezoaeroelastic equations, which are solved using a p-k scheme that accounts for the electromechanical coupling. The evolution of the aerodynamic damping and the frequency of each mode are obtained with changing airflow speed for a given electrical circuit. Expressions for piezoaeroelastically coupled frequency response functions (voltage, current, and electrical power as well the vibratory motion) are also defined by combining flow excitation with harmonic base excitation. Hence, piezoaeroelastic evolution can be investigated in frequency domain for different airflow speeds and electrical boundary conditions.

Improving the Convergence of the Doublet-Lattice Method Through Tip Corrections

2001 ◽  
Vol 38 (4) ◽  
pp. 772-776 ◽  
Author(s):  
Myles L. Baker ◽  
William P. Rodden
Keyword(s):  
Lattice Method ◽  
Doublet Lattice Method

scholarly journals Aircraft Ditching Loads Simulation Tool

2015 ◽  
Vol 798 ◽  
pp. 531-535
Author(s):  
Antonino Bonanni ◽  
Lorenz Vandewaeter ◽  
Caroline Havill ◽  
Prin Kanyoo ◽  
Dominic Taunton ◽  
...  
Keyword(s):  
Pressure Distribution ◽  
Test Case ◽  
Simulation Tool ◽  
Lattice Method ◽  
Research Project ◽  
Dynamic Simulations ◽  
Proprietary Software ◽  
Steady Pressure ◽  
Doublet Lattice Method ◽  
Multi Phase

The present work presents a novel methodology developed for calculating the steady loads acting on aircraft structures in the event of ditching in water. It represents the preliminary result of Stirling Dynamics as part of a NATEP research project. The overall objective of the project is to expand the capabilities of the Stirling Dynamics proprietary software SD-GLOAD (originally designed for ground and crash loads dynamic simulations) to aircraft ditching simulations. The methodology presented in this paper employs a Doublet Lattice Method (DLM) to calculate the steady pressure distribution acting on the submerged parts of the ditching aircraft. The proposed methodology is validated against a higher-fidelity CFD multi-phase model for a selected test-case and several ditching conditions.

Aeroelastic Response to Gust Using CFD Techniques

2010 ◽  
Author(s):  
Ce´dric Liauzun
Keyword(s):  
Numerical Method ◽  
Inviscid Flow ◽  
Lattice Method ◽  
Aeroelastic Response ◽  
Space And Time ◽  
Grid Deformation ◽  
Deformation Speed ◽  
Doublet Lattice Method ◽  
3D Wing

A numerical method to predict the aeroelastic response of an aircraft to a gust is assessed. It is based on the use of CFD techniques to compute accurately the aerodynamic fields. Gust models are then implemented as a field of grid deformation speed, that depends on both space and time. The numerical method has been first validated for a 2D Naca12 airfoil embedded in an inviscid flow and submitted to a sharp edged gust, by comparisons with results presented by Zaide et al. It has afterwards been validated in the case of a 3D wing submitted to a harmonic gust in the subsonic domain by comparisons with computations using the Doublet Lattice Method. After the validation step, the method has been used first to investigate the influence of the aerodynamic nonlinearities that occurs in the transonic domain, and at last to compute the aeroelastic responses of wings to gust excitations.

Low frequency behaviour of the subsonic doublet lattice method

2005 ◽  
Vol 109 (1096) ◽  
pp. 285-271 ◽  
Author(s):  
L. van Zyl
Keyword(s):  
Imaginary Part ◽  
Low Frequency ◽  
Lattice Method ◽  
Real Roots ◽  
Reduced Frequency ◽  
Qualitative Effect ◽  
Doublet Lattice Method ◽  
Limiting Values ◽  
Limiting Value ◽  
Zero Frequency

Abstract The results of the subsonic doublet lattice method (DLM), i.e. generalised unsteady aerodynamic forces (GAFs) at a set of reduced frequencies, are often used as input to the solution of the flutter equation. Solutions of the flutter equation are usually required at many more reduced frequencies than GAFs are calculated for by the DLM and some form of interpolation is therefore required. In the p-k formulation of Rodden, Harder and Bellinger, the imaginary part of the GAFs appear as QI/k, i.e. the imaginary part of the GAFs divided by the reduced frequency. In the case of real (i.e. non-oscillatory) roots of the flutter equation, the solution is determined entirely by the steady GAFs and the limiting value of QI/k at zero frequency. This is also true of the g-method of flutter solution as the two formulations are equivalent at k = 0. Expressions are derived for calculating the limiting values of QI/k directly from the DLM, thereby making the real roots independent of the interpolation of the GAFs. The exact way in which the low frequency DLM results are interpolated has a small effect on the interpolation quality in the case of the p-k flutter equation, whereas it has a significant qualitative effect on the results of the g-method of flutter solution of Chen.

scholarly journals Numerical Computation of Subsonic Oscillatory Airforce Coefficients for Wing-Winglet Configurations

2007 ◽  
Vol 1 (3) ◽  
pp. 303-328
Author(s):  
C.W. Cheung
Keyword(s):  
Computer Program ◽  
Theoretical Development ◽  
Dihedral Angles ◽  
Aircraft Wing ◽  
Lattice Method ◽  
Surface Theory ◽  
Transport Aircraft ◽  
Harmonic Motion ◽  
Doublet Lattice Method ◽  
Stiffness And Damping

This paper presents the theoretical development and numerical results of a lifting-surface theory for calculating oscillating airforce coefficients for wing-winglet configurations and it follows the author's previous paper on the extension of Davies' T-tail theory for cruciform-tail configurations. The wing-winglet configurations are assumed to vibrate in a simple harmonic motion of infinitesimal amplitude in a subsonic airstream such that linearised aerodynamic theory is applicable for the analysis of the motion. The modes of displacement of the wing-winglet configuration may be either symmetric or antisysmmetric with respect to the centre-line of the configuration in the direction of the flow. A computer program has been developed for the evaluation of oscillatory airforce coefficients for wing-winglet configurations. Aerodynamic stiffness and damping matrices which are normally used for aeroelastic calculations have been obtained for a typical transport aircraft wing-winglet configuration at two winglet dihedral angles and comparisons have been made against those calculated by an alternative doublet-lattice method. The comparisons have been shown to be satisfactory.

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