Numerical investigation into vortical flow about a delta-wing configuration up to incidences at which vortex breakdown occurs in experiment

Abstract Recent developments in delta wing aerodynamics are reviewed. For slender delta wings, recent investigations shed more light on the unsteady aspects of shear-layer structure, vortex core, breakdown and its instabilities. For nonslender delta wings, substantial differences in the structure of vortical flow and breakdown may exist. Vortex interactions are generic to both slender and nonslender wings. Various unsteady flow phenomena may cause buffeting of wings and fins, however, vortex breakdown, vortex shedding, and shear layer reattachment are the most dominant sources. Dynamic response of vortex breakdown over delta wings in unsteady flows can be characterised by large time lags and hysteresis, whose physical mechanisms need further studies. Unusual flow–structure interactions for nonslender wings in the form of self-excited roll oscillations have been observed. Recent experiments showed that substantial lift enhancement is possible on a flexible delta wing.

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APPLICATION OF AN EULER SOLVER TO SELECTED PROBLEMS IN FLIGHT DYNAMICS

Aviation ◽

10.3846/16487788.2007.9635956 ◽

2007 ◽

Vol 11 (2) ◽

pp. 13-22

Author(s):

Janusz Sznajder ◽

Jerzy Zółtak

Keyword(s):

Unsteady Flow ◽

Steady Flow ◽

Vortex Breakdown ◽

Delta Wing ◽

Flow Analysis ◽

Vortical Flow ◽

Flow Equations ◽

Euler Solver ◽

Unsteady Flow Analysis

Several applications of a Euler solver with the formulation of the flow equations in the noninertial reference system with steady and unsteady flow analysis are presented. The steady‐flow applications include determination of aerodynamic derivatives with respect to angular velocity and analysis of vortical flow over a delta wing at high angles of attack with the determination of aerodynamic coefficients and analysis of vortex breakdown. The unsteady flow analysis is applied in the simulation of a rapid manoeuvre for the determination of unsteady forces. The results of this simulation are compared with results of simulations using steady‐flow approximation in order to assess the advantages of unsteady flow analysis in the simulation of aircraft manoeuvres.

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A Multidisciplinary Analysis of Tail Buffeting Alleviation Using Streamwise Fences

Journal of Vibration and Control ◽

10.1177/1077546303009005005 ◽

2003 ◽

Vol 9 (5) ◽

pp. 583-604 ◽

Cited By ~ 1

Author(s):

Essam F. Sheta

Keyword(s):

Data Transfer ◽

Vortex Breakdown ◽

Delta Wing ◽

Vortical Flow ◽

Geometrical Shape ◽

Fighter Aircraft ◽

Grid Deformation ◽

Multidisciplinary Analysis ◽

Wide Range ◽

High Angles Of Attack

A multidisciplinary analysis of vertical tail buffeting and buffeting alleviation of generic fighter aircraft is conducted. This complex multidisciplinary problem is solved for the fluid dynamics, structure dynamics, fluid-structure coupling, and grid deformation using a computing environment that controls the temporal synchronization of the data transfer between the analysis modules. The generic fighter aircraft consists of a sharp-edged delta wing with an aspect ratio of one and a swept-back, flexible, vertical twin tail with a taper ratio of 0.23. Twin streamwise fences are located at the 30% chord-station of the delta wing. The fences are used to alter the vortical flow and to delay the onset of vortex breakdown above the delta wing, in order to alleviate the twin-tail buffeting. The effect of the geometrical shape of the fences on the buffeting responses is investigated. The performance of the fences over a wide range of high angles of attack is also investigated. The trapezoidal configuration of the fences at a taper ratio of 0.7 produced the most favorable results. The results indicated that the fences are effective in reducing the aeroelastic loads and responses, especially at angles of attack less than 30°.

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