Velocity Field Over Delta Wings at High Angles of Attack

Velocity Field Over Delta Wings at High Angles of Attack
Author: Devin O. O'Dowd
Publisher:
Total Pages: 66
Release: 1999-02-01
Genre: Airplanes
ISBN: 9781423554370

The study of vortex breakdown over delta wings at high angles of attack (AOA) has been an interest to researchers, mathematicians, and aircraft designers for decades. It is a very hot topic as it relates to many aircraft being designed today and because no complete understanding exists. Most of the understanding that does exist comes in the form of the problems associated with vortex breakdown. Many question if it is possible to control the breakdown to avoid the problems and to aid the aircraft in maneuverability. The purpose of this study is to lay the foundation for future research at the University of Washington, so that the identity to the cause of the vortex breakdown may be found.

Structure and Control of Three-Dimensional Unsteady Flow in Delta Wings at High Angle-of-Attack

Structure and Control of Three-Dimensional Unsteady Flow in Delta Wings at High Angle-of-Attack
Author:
Publisher:
Total Pages: 8
Release: 1995
Genre:
ISBN:

This program has focused on the instantaneous flow structure generated by controlled motion of wings in the pitching and rolling modes, as well as application of local control techniques for mediating the flow structure. The instantaneous flow structure is characterized using high-image-density particle image velocimetry, in conjunction with new types of two and three dimensional imaging techniques. This approach provides instantaneous velocity fields, streamline patterns and vorticity distributions at crucial locations in the flow field and allows a proper basis for eventual control of the flow structure. Characterization of the flow structure in the rolling mode of wing motion has involved definition of the critical states of the flow, based on the static locations of onset of vortex breakdown. The instantaneous crossflow and streamwise topology has been defined as a function of row angle. For pitching motion of the wing, simultaneous maneuver of the wing and application of control in the form of deflection of a leading-edge flap and blowing from the trailing-edge provide an effective, interactive means of altering the onset of vortex breakdown, thereby enhancing the effectiveness of maneuvers at high angle of attack.

Controlled Vortical Flow on Delta Wings Through Unsteady Leading Edge Blowing

Controlled Vortical Flow on Delta Wings Through Unsteady Leading Edge Blowing
Author: National Aeronautics and Space Adm Nasa
Publisher:
Total Pages: 162
Release: 2018-11-18
Genre:
ISBN: 9781731351593

The vortical flow over a delta wing contributes an important part of the lift - the so called nonlinear lift. Controlling this vortical flow with its favorable influence would enhance aircraft maneuverability at high angle of attack. Several previous studies have shown that control of the vortical flow field is possible through the use of blowing jets. The present experimental research studies vortical flow control by applying a new blowing scheme to the rounded leading edge of a delta wing; this blowing scheme is called Tangential Leading Edge Blowing (TLEB). Vortical flow response both to steady blowing and to unsteady blowing is investigated. It is found that TLEB can redevelop stable, strong vortices even in the post-stall angle of attack regime. Analysis of the steady data shows that the effect of leading edge blowing can be interpreted as an effective change in angle of attack. The examination of the fundamental time scales for vortical flow re-organization after the application of blowing for different initial states of the flow field is studied. Different time scales for flow re-organization are shown to depend upon the effective angle of attack. A faster response time can be achieved at angles of attack beyond stall by a suitable choice of the initial blowing momentum strength. Consequently, TLEB shows the potential of controlling the vortical flow over a wide range of angles of attack; i.e., in both for pre-stall and post-stall conditions. Lee, K. T. and Roberts, Leonard BLOWING; DELTA WINGS; FLOW DISTRIBUTION; LEADING EDGES; VORTICES; AIRCRAFT MANEUVERS; ANGLE OF ATTACK; MOMENTUM; NONLINEARITY; STABILITY...

On the Hypersonic Flow Past Blunted, Flat Delta Wings

On the Hypersonic Flow Past Blunted, Flat Delta Wings
Author: Arnold Polak
Publisher:
Total Pages: 48
Release: 1970
Genre: Aerodynamics, Hypersonic
ISBN:

The flow of a perfect gas over the slab portion of a blunted delta wing flying at hypersonic speeds is studied. A set of approximate equations is derived and a solution - for an inviscid flow - is obtained. Using this solution as a representation for the inviscid flow problem, a formulation to the laminar boundary-layer equations is presented; one which is applicable to the flow field's azimuthal planes where the crossflow gradients are not too large. Numerical solutions to these boundary-layer equations have been obtained; however, these are restricted to the azimuthal planes and near to the leading edges. The results indicate the presence of a dividing surface streamline since a numerical solution could not be obtained near the centerplane of the wing, where the crossflow velocity is large. (Author).

High Angle of Attack Aerodynamics

High Angle of Attack Aerodynamics
Author: Josef Rom
Publisher: Springer Science & Business Media
Total Pages: 408
Release: 2012-12-06
Genre: Science
ISBN: 1461228247

The aerodynamics of aircraft at high angles of attack is a subject which is being pursued diligently, because the modern agile fighter aircraft and many of the current generation of missiles must perform well at very high incidence, near and beyond stall. However, a comprehensive presentation of the methods and results applicable to the studies of the complex aerodynamics at high angle of attack has not been covered in monographs or textbooks. This book is not the usual textbook in that it goes beyond just presenting the basic theoretical and experimental know-how, since it contains reference material to practical calculation methods and technical and experimental results which can be useful to the practicing aerospace engineers and scientists. It can certainly be used as a text and reference book for graduate courses on subjects related to high angles of attack aerodynamics and for topics related to three-dimensional separation in viscous flow courses. In addition, the book is addressed to the aerodynamicist interested in a comprehensive reference to methods of analysis and computations of high angle of attack flow phenomena and is written for the aerospace scientist and engineer who is familiar with the basic concepts of viscous and inviscid flows and with computational methods used in fluid dynamics.