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Author : Earl H. Dowell
Publisher :
ISBN 13 :
Total Pages : 24 pages
Book Rating : 4.3/5 (91 download)
Download or read book Limit Cycle Oscillations and Nonlinear Aeroelastic Wing Response written by Earl H. Dowell and published by . This book was released on 2004 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (946 download)
Download or read book Limit Cycle Oscillations and Nonlinear Aeroelastic Wing Response: Reduced Order Aerodynamic Models written by and published by . This book was released on 2003 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: To develop an eigenmode or proper orthogonal decomposition (POD) modal representation of unsteady aerodynamic forces on oscillating flexible airfoils and wings and thereby reduce the size and cost of mathematical models for such forces by several orders of magnitude. Building on earlier work for two-dimensional inviscid flows, we seek to extend our models to. three-dimensional flows with viscous effects included. Also a novel form of the harmonic balance (HB) method had been developed for determining limit cycle oscillations (LCO) of aeroelastic systems.
Author : Earl Dowell
Publisher :
ISBN 13 :
Total Pages : 15 pages
Book Rating : 4.:/5 (452 download)
Download or read book Limit Cycle Oscillations (LCO) and Nonlinear Aeroelastic Wing Response: Reduced Order Aerodynamic Models written by Earl Dowell and published by . This book was released on 1999 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: A nonlinear, aeroelastic analysis of a low aspect, delta wing modeled as a plate of constant thickness demonstrates that limit cycle oscillations (LCO) of the order of the plate thickness are possible. The structural nonlinearity arises from double bending in both the chordwise and spanwise directions. The present results using a vortex lattice aerodynamic model for a low Mach number flow complement earlier studies for rectangular wing platforms that showed similar qualitative results. The theoretical results for the flutter boundary (beyond which LCO occurs) have been validated by comparison to the experimental data reported by other investigators for the low aspect ratio delta wings. Also the limit cycle oscillations found experimentally by previous investigators (but not previously quantified prior to the present work) are consistent with the theoretical results reported here. Reduced order aerodynamic and structural models are used to substantially decrease computational cost with no loss in accuracy. Without the use of reduced order models, calculations of the LCO would be impractical. A wind tunnel model is tested to provide a quantitative experimental correlation with the theoretical results for the LCO response itself.
Author :
Publisher :
ISBN 13 :
Total Pages : 13 pages
Book Rating : 4.:/5 (946 download)
Download or read book Limit Cycle Oscillations (LCO) and Nonlinear Aeroelastic Response: Reduced Order Models written by and published by . This book was released on 2001 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unsteady aerodynamic computational models for aeroelastic phenomena such as flutter and limit cycle oscillations are complex and high dimensional. Under this grant, reduced order models are being developed that offer increased physical insight and greatly reduced computational cost. Transonic flows are emphasized because of their practical importance and significant technical challenge.
Author :
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (946 download)
Download or read book Limit Cycle Oscillations (LCO) and Nonlinear Aeroelastic Wing Response written by and published by . This book was released on 1996 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Limit cycle oscillations (LCO) have been observed for elastic wings at moderate to high angles of attack where separated flow is thought to occur. At transonic flow conditions with shock waves present, flow separation may occur at moderate angles of attack. For higher angles of attack, separation may occur at (low) subsonic conditions. Empirical quasi steady aerodynamic models based on steady state experimental data have shown some success in predicting the observed LCO. New theoretical aeroelastic models are proposed here to improve the prediction of LCO. Also proposed are simple, flow speed experiments to validate these theoretical models with an option for high speed experiments as well.
Author :
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (227 download)
Download or read book Limit Cycle Oscillations (LCO) and Nonlinear Aeroelastic Wing Response written by and published by . This book was released on 1996 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Limit cycle oscillations (LCO) have been observed for elastic wings at moderate to high angles of attack where separated flow is thought to occur. At transonic flow conditions with shock waves present, flow separation may occur at moderate angles of attack. For higher angles of attack, separation may occur at (low) subsonic conditions. Empirical quasi steady aerodynamic models based on steady state experimental data have shown some success in predicting the observed LCO. New theoretical aeroelastic models are proposed here to improve the prediction of LCO. Also proposed are simple, flow speed experiments to validate these theoretical models with an option for high speed experiments as well.
Author : Atlee M. Cunningham
Publisher :
ISBN 13 :
Total Pages : 154 pages
Book Rating : 4.3/5 (91 download)
Download or read book A Generic Nonlinear Aeroelastic Method with Semi-empirical Nonlinear Unsteady Aerodynamics written by Atlee M. Cunningham and published by . This book was released on 1999 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluid-structure interactions (FSI) that involve nonlinear aerodynamic forces are described which affect both aging aircraft, as well as new aircraft. Several cases are presented which contain aerodynamic non linearities that are important in the FSI process and that require different solution approaches from those taken for linear FSI problems. A time-dependent approach is presented which is based on a semi empirical nonlinear aerodynamic model that is fully coupled with the aircraft elastic equations of motion. An early version of this methodology is applied to a wide variety of Limit Cycle Oscillation (LCO) cases for a fighter configuration carrying large underwing stores. The new method is applied to three classes of problems: (1) LCO for bomber and transport type configurations; (2) LCO for a fighter wing; and (3) large amplitude buffet response of a fin subject to server wake turbulence.
Author : Atlee M. Cunningham
Publisher :
ISBN 13 :
Total Pages : 108 pages
Book Rating : 4.3/5 (91 download)
Download or read book A Generic Nonlinear Aeroelastic Method with Semi-empirical Nonlinear Unsteady Aerodynamics written by Atlee M. Cunningham and published by . This book was released on 1999 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluid-structure interactions (FSI) that involve nonlinear aerodynamic forces are described which affect both aging aircraft, as well as new aircraft. Several cases are presented which contain aerodynamic non linearities that are important in the FSI process and that require different solution approaches from those taken for linear FSI problems. A time-dependent approach is presented which is based on a semi empirical nonlinear aerodynamic model that is fully coupled with the aircraft elastic equations of motion. An early version of this methodology is applied to a wide variety of Limit Cycle Oscillation (LCO) cases for a fighter configuration carrying large underwing stores. The new method is applied to three classes of problems: (1) LCO for bomber and transport type configurations; (2) LCO for a fighter wing; and (3) large amplitude buffet response of a fin subject to server wake turbulence.
Author : Ali H. Nayfeh
Publisher : John Wiley & Sons
ISBN 13 : 3527617590
Total Pages : 720 pages
Book Rating : 4.5/5 (276 download)
Download or read book Nonlinear Oscillations written by Ali H. Nayfeh and published by John Wiley & Sons. This book was released on 2008-09-26 with total page 720 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nonlinear Oscillations is a self-contained and thorough treatment of the vigorous research that has occurred in nonlinear mechanics since 1970. The book begins with fundamental concepts and techniques of analysis and progresses through recent developments and provides an overview that abstracts and introduces main nonlinear phenomena. It treats systems having a single degree of freedom, introducing basic concepts and analytical methods, and extends concepts and methods to systems having degrees of freedom. Most of this material cannot be found in any other text. Nonlinear Oscillations uses simple physical examples to explain nonlinear dispersive and nondispersive waves. The notation is unified and the analysis modified to conform to discussions. Solutions are worked out in detail for numerous examples, results are plotted and explanations are couched in physical terms. The book contains an extensive bibliography.
Author : Robert L. Clark (Jr.)
Publisher :
ISBN 13 :
Total Pages : 16 pages
Book Rating : 4.3/5 (91 download)
Download or read book Dynamics and Control of Nonlinear Fluid-structure Interaction written by Robert L. Clark (Jr.) and published by . This book was released on 2003 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Earl H. Dowell
Publisher :
ISBN 13 :
Total Pages : 56 pages
Book Rating : 4.3/5 (91 download)
Download or read book A Study of Uncertainties in Nonlinear Aeroelastic Systems written by Earl H. Dowell and published by . This book was released on 2007 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: A principal goal of the Air Force research program is to develop accurate, reliable and efficient computational models so that laboratory and flight tests may be decreased and/or the results of such tests may be more effective in reducing design and production costs of new Air Force systems. Key challenges in achieving this goal are the uncertainties that exist in computational models. These uncertainties may be a result of the limitations of the mathematical model in representing physical reality, the numerical uncertainties that arise in obtaining (computational) solitions to these models, and/or the uncertainties in the parameters that enter into such models. Examples of each of these uncertainties have been studied for nonlinear aeroelastic systems and the computational results compared with experiment. New highly computationally efficient methods have been developed.
Author : Robert Clark
Publisher : Springer Science & Business Media
ISBN 13 : 1402021062
Total Pages : 770 pages
Book Rating : 4.4/5 (2 download)
Download or read book A Modern Course in Aeroelasticity written by Robert Clark and published by Springer Science & Business Media. This book was released on 2006-01-24 with total page 770 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this new edition, the fundamental material on classical linear aeroelasticity has been revised. Also new material has been added describing recent results on the research frontiers dealing with nonlinear aeroelasticity as well as major advances in the modelling of unsteady aerodynamic flows using the methods of computational fluid dynamics and reduced order modeling techniques. New chapters on aeroelasticity in turbomachinery and aeroelasticity and the latter chapters for a more advanced course, a graduate seminar or as a reference source for an entrée to the research literature.
Author : Grigorios Dimitriadis
Publisher : John Wiley & Sons
ISBN 13 : 1118756460
Total Pages : 944 pages
Book Rating : 4.1/5 (187 download)
Download or read book Introduction to Nonlinear Aeroelasticity written by Grigorios Dimitriadis and published by John Wiley & Sons. This book was released on 2017-03-10 with total page 944 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduction to Nonlinear Aeroelasticity Introduces the latest developments and technologies in the area of nonlinear aeroelasticity Nonlinear aeroelasticity has become an increasingly popular research area in recent years. There have been many driving forces behind this development, increasingly flexible structures, nonlinear control laws, materials with nonlinear characteristics and so on. Introduction to Nonlinear Aeroelasticity covers the theoretical basics in nonlinear aeroelasticity and applies the theory to practical problems. As nonlinear aeroelasticity is a combined topic, necessitating expertise from different areas, the book introduces methodologies from a variety of disciplines such as nonlinear dynamics, bifurcation analysis, unsteady aerodynamics, non-smooth systems and others. The emphasis throughout is on the practical application of the theories and methods, so as to enable the reader to apply their newly acquired knowledge Key features: Covers the major topics in nonlinear aeroelasticity, from the galloping of cables to supersonic panel flutter Discusses nonlinear dynamics, bifurcation analysis, numerical continuation, unsteady aerodynamics and non-smooth systems Considers the practical application of the theories and methods Covers nonlinear dynamics, bifurcation analysis and numerical methods Accompanied by a website hosting Matlab code Introduction to Nonlinear Aeroelasticity is a comprehensive reference for researchers and workers in industry and is also a useful introduction to the subject for graduate and undergraduate students across engineering disciplines.
Author : Ashley Scott Myers
Publisher :
ISBN 13 :
Total Pages : 46 pages
Book Rating : 4.:/5 (271 download)
Download or read book Variability and Model Adequacy in Simulations of Store-induced Limit Cycle Oscillations written by Ashley Scott Myers and published by . This book was released on 2007 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: A prominent phenomenon of the transonic flight regime is the potential for limit cycle oscillation (LCO) development. LCO is a stable oscillation produced by aeroelastic interactions within a component of the aircraft. Such oscillation shortens the fatigue life of the aircraft and increases the amount of maintenance necessary. These aspects are of great concern to the aerospace industry, particularly with high performance military aircraft that are required to operate beyond their planned service lives. The research here focused specifically on the aircraft wing and the influence of external stores attached to that wing on its aeroelastic properties. Monte Carlo simulations were performed to estimate the probability of a wing undergoing limit cycle oscillations due to external stores. Simulations were conducted with a finite element structural model of a wing coupled with multiple subsonic and transonic unsteady aerodynamics solvers to compare computational cost and accuracy. The results provide guidance for implementing probabilistic analysis methods with industry-standard software to predict dangerous aeroelastic response processes that sometimes occur during flight tests. For the low transitional Mach numbers (between 0.7 and 0.88), the linear aerodynamic model was found to be a viable alternative to the more computationally costly alternatives. For Mach numbers above 0.88, nonlinear, viscous methods were necessary.
Author : David Nixon
Publisher :
ISBN 13 :
Total Pages : 410 pages
Book Rating : 4.3/5 (91 download)
Download or read book Unsteady Transonic Aerodynamics written by David Nixon and published by . This book was released on 1989 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume complements Transonic aerodynamics (v.81 in the series) which is concerned with steady flow. This is the only book to address the subject of unsteady transonic aerodynamics, a field much different from steady aerodynamics. The most pronounced difference is the complex shock wave motions
Author : Grigorios Dimitriadis
Publisher : John Wiley & Sons
ISBN 13 : 1118613473
Total Pages : 597 pages
Book Rating : 4.1/5 (186 download)
Download or read book Introduction to Nonlinear Aeroelasticity written by Grigorios Dimitriadis and published by John Wiley & Sons. This book was released on 2017-05-01 with total page 597 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduces the latest developments and technologies in the area of nonlinear aeroelasticity Nonlinear aeroelasticity has become an increasingly popular research area in recent years. There have been many driving forces behind this development, increasingly flexible structures, nonlinear control laws, materials with nonlinear characteristics, etc. Introduction to Nonlinear Aeroelasticity covers the theoretical basics in nonlinear aeroelasticity and applies the theory to practical problems. As nonlinear aeroelasticity is a combined topic, necessitating expertise from different areas, the book introduces methodologies from a variety of disciplines such as nonlinear dynamics, bifurcation analysis, unsteady aerodynamics, non-smooth systems and others. The emphasis throughout is on the practical application of the theories and methods, so as to enable the reader to apply their newly acquired knowledge. Key features: Covers the major topics in nonlinear aeroelasticity, from the galloping of cables to supersonic panel flutter. Discusses nonlinear dynamics, bifurcation analysis, numerical continuation, unsteady aerodynamics and non-smooth systems. Considers the practical application of the theories and methods. Covers nonlinear dynamics, bifurcation analysis and numerical methods. Accompanied by a website hosting Matlab code. Introduction to Nonlinear Aeroelasticity is a comprehensive reference for researchers and workers in industry and is also a useful introduction to the subject for graduate and undergraduate students across engineering disciplines.
Author : American Institute of Aeronautics and Astronautics
Publisher :
ISBN 13 :
Total Pages : 1380 pages
Book Rating : 4.F/5 ( download)
Download or read book AIAA Journal written by American Institute of Aeronautics and Astronautics and published by . This book was released on 2006 with total page 1380 pages. Available in PDF, EPUB and Kindle. Book excerpt:
