The Suppression of Single-Fin Buffeting Using Tangential Leading Edge Blowing on a Delta Wing

1992 ◽  
Vol 206 (2) ◽  
pp. 93-104
Author(s):  
D E Bean ◽  
N J Wood ◽  
D G Mabey
Keyword(s):  
Flow Visualization ◽  
Delta Wing ◽  
Leading Edge ◽  
Light Sheet ◽  
Vortical Flow ◽  
Delta Wings ◽  
Pressure Transducers ◽  
Buffeting Response ◽  
Flexible Fin ◽  
The University

The application of tangential leading edge blowing to reduce levels of single-fin buffeting has been studied. The tests were performed at the University of Bath in the 2.1 m × 1.5 m wind tunnel using two cropped 60° delta wings. To measure the buffet excitation, a rigid fin instrumented with miniature differential pressure transducers was used. A flexible fin of similar planform and size was used to measure the buffeting response. Steady state static pressure data and laser light sheet flow visualization were employed to aid interpretation of the vortical flow over the wings, and hence identify the causes of the buffeting. The profiles of the buffet excitation and response were found to match each other very closely. It was observed that the leading edge blowing modified the leading edge vortices by reducing the ‘effective angle of attack’ of the vortex. Blowing at a constant rate shifted the buffet excitation and response to higher angles of attack. Flow visualization confirmed that the mechanism at peak buffeting had not changed, but had been merely shifted. It has been shown that the use of an optimum blowing programme could completely suppress the buffeting response.

scholarly journals An Initial Investigation of Adjoint-Based Unstructured Grid Adaptation for Vortical Flow Simulations

2011 ◽  
Vol 2011 ◽  
pp. 1-9
Author(s):  
Li Li
Keyword(s):  
Unstructured Grid ◽  
Delta Wing ◽  
Leading Edge ◽  
Grid Resolution ◽  
Vortical Flow ◽  
Delta Wings ◽  
Flow Simulations ◽  
Grid Adaptation ◽  
Grid Points ◽  
Adaptation Method

A computational fluid dynamics (CFDs) method utilizing unstructured grid technology has been employed to compute vortical flow around a65°delta wing with sharp leading edge, which is specially known as the geometry of the second international vortex flow experiment (VFE-2). In VFE-2,65°delta wings with different leading edges had been broadly investigated by experiments, which resulted in a special database for CFDs codes validation. The emphasis of this paper is to investigate the effectiveness of an adjoint-base grid adaptation method for unstructured grid in capturing concentrated vortices generated at sharp edges or flow separation lines of lifting surfaces flying at high angles of attack. Earlier experiences in vortical flow simulations had indicated that the vortex behavior is highly dependent on the local grid resolution both on body surface and space. The adjoint-based adaptation method used here is hoped to save grid points with a reasonable grid resolution for vortical flow simulations. The basic idea is to construct a new adaptive sensor in a grid adaptation process with the intent to tell where the elements should be smaller or larger by introducing an adjoint formulation to relate the estimated functional error to local residual errors of both the primal and adjoint solutions.

Separated Flow Past a Slender Delta Wing at Incidence

1973 ◽  
Vol 24 (2) ◽  
pp. 120-128 ◽  
Author(s):  
J E Barsby
Keyword(s):  
Delta Wing ◽  
Separated Flow ◽  
Leading Edge ◽  
Vortex Sheet ◽  
Simultaneous Equations ◽  
Delta Wings ◽  
Nested Iteration ◽  
Finite Difference Technique ◽  
Flow Past ◽  
Vortex Systems

SummarySolutions to the problem of separated flow past slender delta wings for moderate values of a suitably defined incidence parameter have been calculated by Smith, using a vortex sheet model. By increasing the accuracy of the finite-difference technique, and by replacing Smith’s original nested iteration procedure, to solve the non-linear simultaneous equations that arise, by a Newton’s method, it is possible to extend the range of the incidence parameter over which solutions can be obtained. Furthermore for sufficiently small values of the incidence parameter, new and unexpected results in the form of vortex systems that originate inboard from the leading edge have been discovered. These new solutions are the only solutions, to the author’s knowledge, of a vortex sheet leaving a smooth surface.Interest has centred upon the shape of the finite vortex sheet, the position of the isolated vortex, and the lift, and variations of these quantities are shown as functions of the incidence parameter. Although no experimental evidence is available, comparisons are made with the simpler Brown and Michael model in which all the vorticity is assumed to be concentrated onto an isolated line vortex. Agreement between these two models becomes very close as the value of the incidence parameter is reduced.

A Note on the Vorticity Distribution on the Surface of Slender Delta Wings with Leading Edge Separation

1961 ◽  
Vol 65 (603) ◽  
pp. 195-198 ◽  
Author(s):  
B. J. Elle ◽  
J. P. Jones
Keyword(s):  
Experimental Evidence ◽  
Delta Wing ◽  
Leading Edge ◽  
Water Tunnel ◽  
Delta Wings ◽  
Vorticity Distribution ◽  
Edge Separation

A description is given of the distribution of vorticity in the surface of thin wings with large leading edge sweep. Although the delta wing is chosen as the basic plan form the deductions are general and applicable to other types of wing. The conclusions are illustrated with experimental evidence from a water tunnel.

410 Flow Visualization and Pressure Measurement of Sawtooth Leading Edge Delta Wings

2007 ◽  
Vol 2007.45 (0) ◽  
pp. 133-134
Author(s):  
Susumu KATO ◽  
Makoto OKANO ◽  
Takashi MATSUNO ◽  
Hiroshi IWATA ◽  
Hiromitsu KAWAZOE
Keyword(s):  
Flow Visualization ◽  
Pressure Measurement ◽  
Leading Edge ◽  
Delta Wings

Experimental and Computational Studies of Twin-Vertical-Tail Buffet

2008 ◽  
Vol 33-37 ◽  
pp. 1241-1246
Author(s):  
Qing Yang ◽  
J.J. Li ◽  
Y.N. Yang ◽  
Z.Y. Ye
Keyword(s):  
Euler Equations ◽  
Three Dimensional ◽  
Bending Moment ◽  
Leading Edge ◽  
Light Sheet ◽  
Vortical Flow ◽  
Wind Tunnel Experiments ◽  
Rigid Model ◽  
Tail Buffet ◽  
Low Speed Wind Tunnel

Characteristics and mechanism of twin-vertical-tail buffet response on airplane configuration with wing root leading edge extension (LEX) were studied by both experiment and computation. Low-speed wind tunnel experiments were carried out to measure the root bending moment and tip acceleration of vertical tail. Vortical flow patterns were visualized via laser light sheet technique. Three-dimensional computation was performed to solve the unsteady Euler equations on rigid model. The results indicate that (1) bursting of vortices emanating from LEX is the main source of twin-vertical-tail buffet; (2) the Euler equations is able to predict the general characteristics of vertical-tail buffet response reasonably.

Flow Regimes over Delta Wings at Supersonic and Hypersonic Speeds

1976 ◽  
Vol 27 (1) ◽  
pp. 1-14 ◽  
Author(s):  
L C Squire
Keyword(s):  
Shock Layer ◽  
Delta Wing ◽  
Leading Edge ◽  
Flow Regimes ◽  
Lower Surface ◽  
Delta Wings ◽  
Thin Shock Layer ◽  
Wide Range ◽  
Wing Sweep ◽  
Edge Separation

SummaryThis paper concerns the boundaries between flow regimes for sharp-edged delta wings in supersonic flow and the relation of some predictions of thin-shock-layer theory to these boundaries. In particular, it is shown that the theory predicts that the attachment lines on the lower surface of a thin delta wing at supersonic speeds suddenly jump from just inboard of the leading edges to the centre line in certain flight conditions. In general there is close agreement between the conditions for this jump and the flight conditions corresponding to the change-over from attached flow to the leading-edge separation on the upper surface. Since the movement of the attachment lines on the lower surface must change the position of the sonic line and the nature of the expansion around the edge, it is suggested that the two phenomena are directly related. Thus thin-shock-layer theory can be used to establish the boundaries of the various flow regimes for a wide range of Mach number, incidence and wing sweep. The theory can also be used to predict the effects of wing thickness on leading-edge separation, but here the experimental data is very sparse and somewhat contradictory, so the value of the prediction in the case of thickness requires further investigation.

Lift Force of Delta Wings

1990 ◽  
Vol 43 (9) ◽  
pp. 209-221 ◽  
Author(s):  
Mario Lee ◽  
Chih-Ming Ho
Keyword(s):  
Lift Force ◽  
Delta Wing ◽  
Angle Of Attack ◽  
Leading Edge ◽  
Surface Flux ◽  
Experimental Results ◽  
Geometrical Parameters ◽  
Two Dimensional ◽  
Delta Wings ◽  
Vorticity Balance

On a delta wing, the separation vorticies can be stationary due to the balance of the vorticity surface flux and the axial convection along the swept leading edge. These stationary vortices keep the wing from losing lift. A highly swept delta wing reaches the maximum lift at an angle of attack of about 40°, which is more than twice as high as that of a two-dimensional airfoil. In this paper, the experimental results of lift forces for delta wings are reviewed from the perspective of fundamental vorticity balance. The effects of different operational and geometrical parameters on the performance of delta wings are surveyed.

Fin Buffeting Characteristics of a Generic Single Fin Aircraft

1996 ◽  
Vol 210 (3) ◽  
pp. 247-260 ◽  
Author(s):  
T R Chesneau ◽  
N J Wood
Keyword(s):  
Angle Of Attack ◽  
Leading Edge ◽  
Buffeting Response ◽  
Vortex Pairs ◽  
Wide Range ◽  
Flexible Fin ◽  
Using Data

Experiments have been performed to investigate the fin buffeting characteristics of a generic single fin aircraft. A variety of configurations, including high wing, mid wing and low wing have been examined, some with the addition of leading edge extensions, foreplanes and cheek intakes. The fin buffeting was measured using a flexible fin, which was related to the buffet pressure flowfield using data from an alternative, pressure tapped, rigid fin. Results have been obtained over a wide range of angles of attack at low subsonic speeds. The production of upstream vortices affects the progression of the primary wing vortex with angle of attack to alter the fin buffeting response. The results indicate that the high wing configurations are sensitive to the presence of additional vortex pairs emanating from forebody features. For low wing configurations, peak buffeting magnitudes may be significantly affected by foreplane incidence in a canard configuration. The interaction between foreplane, wing and body vortices is complex and may result in either reduced or increased levels of buffeting response.

Alleviation of pitch-up on delta wings using distributed porosity

1999 ◽  
Vol 103 (1025) ◽  
pp. 339-347 ◽  
Author(s):  
L. W. Traub ◽  
B. Moeller ◽  
S. F. Galls
Keyword(s):  
Experimental Investigation ◽  
Flow Field ◽  
Delta Wing ◽  
Leading Edge ◽  
Surface Flow ◽  
Force Balance ◽  
Flow Visualisation ◽  
Surface Porosity ◽  
Delta Wings ◽  
Field Surveys

Abstract An experimental investigation was undertaken to determine the effectiveness of distributed surface porosity for the alleviation of pitch-up on a delta wing. Tests were undertaken using a 65° sweep delta wing with distributed porosity evaluated at various locations on the wing. Force balance, on and off surface flow visualisation and flow field surveys using a multi-hole probe were undertaken. The data shows that distributed porosity applied along the wing leading edge at the apex is effective in eliminating pitch-up whilst incurring a minimal performance cost. Trailing edge porosity generally degraded performance.

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