3 edition of Non-linear unsteady wing theory found in the catalog.
Non-linear unsteady wing theory
by National Aeronautics and Space Administration, National Technical Information Service, distributor in [Washington, DC, Springfield, Va
Written in English
|Other titles||Non linear unsteady wing theory|
|Series||NASA contractor report -- NASA CR-181008|
|Contributions||United States. National Aeronautics and Space Administration|
|The Physical Object|
Abstract. This paper extends a previous study by Wu (Adv. Appl. Mech. ; ) to continue developing a fully non-linear theory for calculation of unsteady flow generated by a two-dimensional flexible lifting surface moving in arbitrary manner through an incompressible and inviscid fluid for modelling bird/insect flight and fish swimming. For sub- or super-sonic flow linearized theory is known to hold well for thin wings. For transonic flow, however, the above-mentioned non-linear accumulation of disturbances precludes the use of linearized theory in the steady, non-lifting case no matter how thin the wing is. In the oscillating wing case the situation is somewhat better, though.
A Geometrically Non-Linear Time-Domain Unsteady Lifting-Line Theory M. V. A computational study of a canonical pitch-up, pitch-down wing maneuver. In 39th AIAA Fluid Dynamics Conference. AIAA Paper Fage, A. & Johansen, F. C. On the A Geometrically Non-Linear Time-Domain Unsteady Lifting-Line Theory. CrossRef;. straked wing is considered for post stall ma-noeuvres, and observations of chaotic motion in post stall manoeuvres are guided. 1 Introduction An aircraft is the inherently non-linear and time varying system. Non-linear dynamics is central to several important aircraft .
1 Estimation of unsteady aerodynamics in the wake of a freely flying European starling Hadar Ben-Gida1, Adam Kirchhefer2, Zachary J. Taylor1, Wayne Bezner-Kerr3, Christopher G. Guglielmo3, Gregory A. Kopp2 and Roi Gurka4 1 School of Mechanical Engineering, Tel-Aviv University, Tel-Aviv, , Israel 2 Boundary Layer Wind Tunnel Laboratory, Faculty of Engineering, University of Western. "A method is presented for calculating wing characteristics by lifting-line theory using nonlinear section lift data. Material from various sources is combined with some original work into the single complete method described. Multhopp's systems of multipliers are employed to obtain the induced angle of attack directly from the spanwise lift distribution.
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Ing line theory apply to the method, viz. moderate to high wing aspect ratio, moderate sweep angle and incompressible flow. Additional assumptions are also implicit regard-ing effects of the unsteady now or aection chordwise load distributions and stall.
Arbitrary nonlinear section lft curves may be introduced, and time histories of the. In the first part of this study, analysis of 2D unsteady airfoil behavior was developed along lines analogous to classical theory, except that no linearizing assumptions were admitted. Successful use of certain convective characteristic variables [i] has led to a viable non-linear wing theory for unsteady flow past airfoils in violent motion.
The Prandtl lifting-line theory is a mathematical model that predicts lift distribution over a three-dimensional wing based on its geometry. It is also known as the Lanchester–Prandtl wing theory. The theory was expressed independently by Frederick W. Lanchester inand by Ludwig Prandtl in – after working with Albert Betz and Max Munk.
In this model, the vortex loses. Download Citation | A non‐linear unsteady flexible wing theory | This paper extends a previous study by Wu (Adv. Appl. Mech. ; –) to continue developing a fully non-linear theory. model includes: i) a wing topology inspired by gull wings; ii) a kinematical model to describe the process of wing adaptation based on one mechanism observed in the flight of gulls (folding-wing approach); and iii) a version of the unsteady vortex-lattice methods (UVLM) that allows taking nonlinear and unsteady aerodynamic phenomena into account.
Numerical algorithms and solutions of generalized nonlinear lifting-line theory over an elliptical wing are examined, with emphasis on near/poststall flows.
First, a thorough analysis on the. Non-Linear Unsteady Aerodynamic Response Approximation Using Multi-Layer Functionals Journal of the Brazilian Society of Mechanical Sciences, Vol.
24, No. 1 Reduced-Order Models for Nonlinear Unsteady Aerodynamics. Recently, a nonlinear unsteady wing theory has been introduced by Wu - along this approach to provide an optimally uniﬁed analytical and numerical method for computation of solutions on speciﬁc premises. This nonlinear theory has been applied by Stredie () and Hou et al.
()[7,8] to perform computations of a. A non-linear unsteady flexible wing theory 1 January | Structural Control and Health Monitoring, Vol. 13, No. 1 Unsteady Aerodynamic Modeling with Time-Varying Free-Stream Mach Numbers.
Abstract The essence of this two-part paper is the analytical, aerodynamic modelling of insect-like flapping wings in the hover for micro-air-vehicle applications. A key feature of such flapping-wing flows is their unsteadiness and the formation of a leading-edge vortex in addition to the conventional wake shed from the trailing edge.
What ensues is a complex interaction between the shed wakes. Get this from a library. Non-linear unsteady wing theory. [J E McCune; United States. National Aeronautics and Space Administration.]. Wing morphology. The modelling process begins with definition of the wing shape in terms of chord distribution as a function of span.
In this work, we use the procedure proposed by Ellington  to define the chord distribution through a beta function representation provides a compact analytical description of wing shape using just three variables: wing length, mean.
Non-linear unsteady wing theory, part 1. Quasi two-dimensional behavior: Airfoils and slender wings. By J. Mccune. Abstract. The initial phases of a study of the large-amplitude unsteady aerodynamics of wings in severe maneuver are reported.
The research centers on vortex flows, their initiation at wing surfaces, their subsequent convection. A non‐linear unsteady flexible wing theory A non‐linear unsteady flexible wing theory Housner, George W.; Knowles, James K.; Kobori, Takuji; Masri, Sami F.
This paper extends a previous study by Wu (Adv. Appl. Mech. ; –) to continue developing a fully non‐linear theory for calculation of unsteady flow. Introduction. The classical lifting line theory (LLT), developed by Prandtl a century ago provided the first satisfactory analytical treatment for the evaluation of the aerodynamics of a finite wing [1–6].The LLT laid the foundation for understanding the aerodynamics of flight, and is still widely used today to provide accurate predictions of the lift and induced drag for 3d wings .
The unsteady vortex-lattice method (UVLM) is an efficient computational technique to solve 3D potential flow problems about lifting surfaces. Vortex rings are distributed over the mean surface and the non-penetration boundary condition is imposed at a number of collocation points, leading to a system of algebraic equations.
However, there is no convincing alternative to the Kutta condition, even though it is not mathematically derived. Realizing that the lift generation and vorticity production are essentially viscous processes, we provide a viscous extension of the classical theory of unsteady aerodynamics by.
The aerodynamic analysis of wings and their vortex wakes is discussed from a perspective of its relation to the work of Ka´rma´n and Sears. The key concepts from this early paper on the analysis of airfoils in small amplitude unsteady motion are reviewed. A method is presented to model the incompressible, attached, unsteady lift and pitching moment acting on a thin three-dimensional wing in the time domain.
The model is based on the combination of Wagner theory and lifting line theory through the unsteady Kutta–Joukowski theorem.
The results are a set of closed-form linear ordinary differential equations that can be solved analytically or. Appendix A Unsteady potential flow solution Slender wing theory involves solving the continuity equation for inviscid, irrota- tional flow for wings with A~.
An approach to lifting wing theory at Mach one is presented that utilizes an integral method similar to the Karman-Pohlhausen method in boundary layer theory. As in any integral method the results obtained are approximate in nature. Nonetheless, comparison with experimental data shows good agreement in cases for which experimental data are.unsteady vortex-lattice and panel methods.5,6 Current computational capabilities allow for high- delity, 3D, unsteady Navier-Stokes simulations of apping wings.
A number of detailed CFD studies have been completed, including work by Jones, et. al.,7,8 Shyy et. al.,11 Persson et. al.,9 and Ou et. al There has also been long-standing research interest in optimization of.CiteSeerX - Document Details (Isaac Councill, Lee Giles, Pradeep Teregowda): This paper presents an adjoint method for the optimum shape design of unsteady flows.
The goal is to develop a set of discrete unsteady adjoint equations and the corresponding boundary condition for the non-linear frequency domain method.
First, this paper presents the complete formulation of the time dependent.