3 edition of Flutter suppression control law synthesis for the active flexible wing model found in the catalog.
Flutter suppression control law synthesis for the active flexible wing model
1989 by National Aeronautics and Space Administration, Langley Research Center in Hampton, Va .
Written in English
|Statement||Vivek Mukhopadhyay, Boyd Perry III, and Thomas E. Noll.|
|Series||NASA technical memorandum -- 101584.|
|Contributions||Perry, Boyd., Noll, Thomas E., Langley Research Center.|
|The Physical Object|
In Section 4numerical simulations are given to demonstrate the effectiveness and robustness of the proposed active flutter controller against changing flight parameters in a wide transonic regime. Part of the Springer Proceedings in Physics book series SPPHY, volume Abstract This paper presents a fundamental study of flutter characteristics and control performance of an aeroelastic system based on a two-dimensional double wedge wing in the hypersonic regime. The actuators on either side of the neutral axis are commanded to act in unison, rather than in opposition, to produce extensional strains and equivalent extensional forces. Similar performance data was also calculated for each wing skin in a nominal configuration controlled by conventional articulated control surfaces. The induced camber and twist were then calculated for each section. From the results of the calculation, the author obtains the velocity field, pressure field distribution of H-type vertical axis wind turbine airfoil at different moments and analyze the wind wheel blade torque variation.
When only one of the four available actuators is used, a finite stable MIMO zero of the full Hamiltonian system is found and only one pole is able to move along a stable Butterworth pattern. In the configuration described, all the design variables have been fixed except the thickness of the actuator layer. Examples of dynamic aeroelastic phenomena are: Flutter[ edit ] Flutter is a dynamic instability of an elastic structure in a fluid flow, caused by positive feedback between the body's deflection and the force exerted by the fluid flow. In this paper, based on Navier-Stokes equations numerical simulation and two dimensional wind tunnel testing, the drag measuring technique for high lift configuration in low speed wind tunnel is researched. The adaptive airfoils were designed and analyzed by dividing each of the nominal airfoils into several sections and designing induced strain actuators for each section. Very recently, Lee and Singh proposed an adaptive control system for an uncertain aeroelastic system by using leading-edge and trailing-edge control surfaces [ 11 ].
In a linear system"flutter point" is the point at which the structure is undergoing simple harmonic motion —zero net damping —and so any further decrease in net damping will result in a self-oscillation and eventual failure. Both optimal and suboptimal designs will be examined in the trade studies, discussed in Part II of this paper. Four adaptive wing designs were examined for each skin subject to induced twist or camber deformations. Wright, J. In the analysis which follows, the governing relations for both camber and twist control are developed. Greater control is also realized by actuators which have a high elastic modulus, which is evident upon examination of the roll of the relative stiffness parameter in the optimal lift equations, These observations explain why the shape memory alloys outperformed the piezoceramic adaptive structures in the static control analysis performed.
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System Design Turbulence, especially near supersonic speeds, can cause an aircraft's wings to flutter, i. Writing the equations in terms of non-dimensional mass M, stiffness K, forcing f and disturbance d matrices in the Laplace domain yields.
Finally, some conclusions are drawn in Section 5. The percent weight added is found by dividing Eq. Thus, the control objective is to add damping to the modes of the system [Miller, ].
Test Procedure The example uses the following system test procedure: Read a set of flight conditions from an Excel spreadsheet.
The designers only need input some parameters, then the contrarotating propellers model could be produced automatically. Only the steady state aerodynamic terms are retained to simplify the initial examination of the problem.
However, when the flap deflection limits are reached, the close-loop system with the simple discretized control system loses control.
Furthermore, control compensation developed by theoretical analysis was proposed to make the system stable again. Schilling, S. Zhao: Aerospace Science and Technology, Vol. Karpouzian, G. The three solid curves on each plot measure the performance of each induced strain actuator.
In the analysis which follows, the governing relations for both camber and twist control are developed. Even changing the mass distribution of an aircraft or the stiffness of Flutter suppression control law synthesis for the active flexible wing model book component can induce flutter in an apparently unrelated aerodynamic component.
The foregoing study confirmed the utility of distributed actuators for effecting some forms of control of a wing or sheet. By substituting the material and geometric properties of a typical win, actual optimal actuator layer thicknesses can be calculated.
The first six modes are the first bending mode of the wing, the first torsional mode of the wing, the second bending mode of the wing, the in-plane bending mode of the missile, the first bending mode of the missile, and the second torsional mode of the wing, respectively.
This expression, which relates the optimal actuator layer height to the geometrical and material properties of the wing, can be used in two ways. Silvac: Journal of Fluids and Structures, Vol. Compared with the vast body of applications of adaptive controls to aeroelastic systems, only a few adaptive control strategies involving the variation of flight conditions have been available.
The most beneficial actuators are those which produce large actuation strains and are light weight.An adaptive sheet structure with distributed strain actuators is controlled by a dynamic compensator that implements multiple input, multiple output control laws derived by model-based, e.g., Linear Quadratic Gaussian (LQG) control methodologies.
An adaptive lifting surface is controlled for maneuver enhancement, flutter and vibration suppression and gust and load alleviation with piezoceramic Cited by: This is the first book on adaptive aeroservoelasticity and it presents the nonlinear and recursive techniques for adaptively controlling the uncertain aeroelastic dynamics Covers both linear and nonlinear control methods in a comprehensive manner Mathematical presentation of adaptive control concepts is rigorous Several novel applications of adaptive control presented here are not to be found.
System Design Requirement. The design requirement to be tested in this example is that the flutter suppression system damps out wing pitch oscillations caused by turbulence, i.e., momentary disturbances in the aerodynamic forces acting on the aircraft's wing over a range of flight conditions (speed, altitude, and desired wing pitch).The synthesis and experimental validation of a control law for an active flutter suppression system for the active flexible wing mind-tunnel model is presented.MODEL MODIFICATION OF TRANSONIC AERODYNAMIC FORCE ON A HIGH-ASPECT-RATIO AEROELASTIC WING AND ITS ACTIVE FLUTTER where ωn is the natural frequency of the actuator, ζ the damping coefficient, δc the command and w a white noise included in the.Flutter suppression ebook law design and wind-tunnel test results in transonic flow for a NACA wing model, under the benchmark active control technology program at NASA Langley Research.