Vortex breakdown location over 65° delta wings empiricism and experiment

2004 ◽  
Vol 108 (1087) ◽  
pp. 475-482 ◽  
Author(s):  
C. E. Jobe
Keyword(s):  
Vortex Breakdown ◽  
Leading Edge ◽  
Sudden Expansion ◽  
Navier Stokes ◽  
Prediction Methods ◽  
Data Sets ◽  
Tunnel Wall ◽  
Delta Wings ◽  
Static Tests ◽  
Static Test

Abstract Thirty-eight data sets from static tests of various 65° delta wings in many water and wind tunnels are compared with four empirical vortex breakdown location prediction methods and the results of two Navier-Stokes computations to assess their range of validity in pitch. Vortex breakdown is the sudden expansion and subsequent chaotic evolution of the otherwise orderly, spiraling, leading-edge vortex flow over the upper surface. Large fluctuations occur in vortex breakdown location at static test conditions making accurate experimental determination difficult. The prediction methods do not account for the seemingly minor geometric details that vary between the models such as thickness, leading-edge bevel angle and radius, trailing-edge bevel angle, sting mounting, instrument housings, etc. These geometric variations significantly affect the position of vortex breakdown and degrade the accuracy of the predictions. The large changes in the flow produced by small geometric changes indicate that an efficient flow control strategy may be possible. Many of the data sets are not corrected for tunnel wall effects, which may account for some of the differences. Data presented herein are as published by the original authors, without additional corrections.

Prediction of tunnel wall upwash for delta wings including vortex breakdown effects

1999 ◽  
Vol 103 (1021) ◽  
pp. 139-142 ◽  
Author(s):  
L. W. Traub
Keyword(s):  
Vortex Breakdown ◽  
Side Wall ◽  
Vortical Flow ◽  
Navier Stokes ◽  
Wall Effects ◽  
Integral Expression ◽  
Image System ◽  
Tunnel Wall ◽  
Delta Wings ◽  
Side Walls

AbstractAn incompressible method is presented to predict the upwash corrections associated with vortical flow as a result of wind-tunnel side wall effects. An image system is used to simulate the tunnel side walls which are assumed to be solid. An integral expression is formulated, representing the average upwash induced over the wing by the image system. Wall effects may be determined for flows with and without vortex breakdown. Comparisons of the results with upwash predictions from a Navier-Stokes study show close accord. The upwash expression also displayed the ability to successfully predict corrections for flows involving vortex breakdown.

On the Breakdown at High Incidences of the Leading Edge Vortices on Delta Wings

1960 ◽  
Vol 64 (596) ◽  
pp. 491-493 ◽  
Author(s):  
B. J. Elle
Keyword(s):  
High Speed ◽  
Recent Article ◽  
Vortex Breakdown ◽  
Leading Edge ◽  
Critical Value ◽  
Delta Wings ◽  
Edge Separation ◽  
Leading Edge Vortices

In a recent article, H. Werlé, has described how the free spiral vortices on delta wings with leading edge separation suddenly expand if the incidence is increased beyond a critical value. His description conforms to a great extent with the results, arrived at during an English investigation of the same phenomenon (called the vortex breakdown), but the interpretations of the observations, suggested by the two sources, are different. Against this background it is felt that some further comments and some pertinent high speed observations, may be of interest.

On the Vortex Breakdown Phenomenon in High Angle of Attack Flows Over Delta Wing Geometries

2014 ◽  
Author(s):  
Eric D. Robertson ◽  
Varun Chitta ◽  
D. Keith Walters ◽  
Shanti Bhushan
Keyword(s):  
Vortex Breakdown ◽  
Delta Wing ◽  
Angle Of Attack ◽  
Leading Edge ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
High Angle ◽  
High Angle Of Attack ◽  
Eddy Simulation ◽  
Wing Model

Using computational methods, an investigation was performed on the physical mechanisms leading to vortex breakdown in high angle of attack flows over delta wing geometries. For this purpose, the Second International Vortex Flow Experiment (VFE-2) 65° sweep delta wing model was studied at a root chord Reynolds number (Recr) of 6 × 106 at various angles of attack. The open-source computational fluid dynamics (CFD) solver OpenFOAM was used in parallel with the commercial CFD solver ANSYS® FLUENT. For breadth, a variety of classic closure models were applied, including unsteady Reynolds-averaged Navier-Stokes (URANS) and detached eddy simulation (DES). Results for all cases are analyzed and flow features are identified and discussed. The results show the inception of a pair of leading edge vortices originating at the apex for all models used, and a region of steady vortical structures downstream in the URANS results. However, DES results show regions of massively separated helical flow which manifests after vortex breakdown. Analysis of turbulence quantities in the breakdown region gives further insight into the mechanisms leading to such phenomena.

Circulation criterion to predict leading-edge vortex breakdown over delta wings

1997 ◽  
Author(s):  
X. Huang ◽  
Y. Sun ◽  
E. Hanff ◽  
X. Huang ◽  
Y. Sun ◽  
...  
Keyword(s):  
Vortex Breakdown ◽  
Leading Edge ◽  
Delta Wings ◽  
Leading Edge Vortex ◽  
Edge Vortex

Comparison of Euler and Navier-Stokes solutions for vortex flow over a delta wing

1988 ◽  
Vol 92 (914) ◽  
pp. 145-153 ◽  
Author(s):  
A. Rizzi ◽  
B. Müller
Keyword(s):  
Large Scale ◽  
Stokes Equations ◽  
Delta Wing ◽  
Cross Flow ◽  
Leading Edge ◽  
Navier Stokes ◽  
Delta Wings ◽  
Navier Stokes Equations ◽  
Starting Location ◽  
Secondary Vortices

Summary A numerical method has been developed recently to solve the Navier-Stokes equations for laminar compressible flow around delta wings. A large-scale Navier-Stokes solution on a mesh of 129 × 49 × 65 points for transonic flow Mx = 0·85, α = 10° and Rex = 2·38 × 106 around a 65° swept delta wing with round leading edge is presented and compared with a correspondingly large-scale Euler solution. The viscous results reveal the presence of primary, secondary, and even tertiary vortices. The starting location of the primary vortex is seen to be quite different in the two solutions. In the viscous solution it starts at the wing apex, but in the Euler results it starts about one quarter chord downstream. The secondary reparations are also different, due to the up-lifting of the boundary layer in the viscous results, but to a cross-flow shock in the Euler computation. Comparison with experiment shows that the interaction between the primary and secondary vortices in the Navier-Stokes computation is obtained correctly and that these results are a more realistic simulation than the one given by the Euler equations.

Navier Stokes computation of the flow field over delta wings with spanwise leading edge blowing

1988 ◽  
Author(s):  
DAVID YEH ◽  
DOMINGO TAVELLA ◽  
LEONARD ROBERTS ◽  
KOZO FUJII
Keyword(s):  
Flow Field ◽  
Leading Edge ◽  
Navier Stokes ◽  
Delta Wings

Unsteady Characteristics over Dynamic Delta Wings

2011 ◽  
Vol 128-129 ◽  
pp. 350-353
Author(s):  
Ming Lu Zhang ◽  
Yi Ren Yang ◽  
Zhi Yong Lu
Keyword(s):  
Wind Tunnel ◽  
Vortex Breakdown ◽  
Delta Wing ◽  
Water Channel ◽  
Spiral Wave ◽  
Leading Edge ◽  
Wave Frequency ◽  
Delta Wings ◽  
Static State ◽  
Unsteady Characteristics

A study of flow and frequency characteristics of the leading-edge vortices over a delta wing undergoing pitching up-stop motions is presented. The experiments with the dynamic delta wings were conducted in a water channel and a wind tunnel respectively. Among them, the test of the flow visualization was completed in the water channel with the delta wing with pitching up-stop motions. The result shows that in the case of pitching up-stop movement the vortex breakdown position is dependent on the range of incidence at which the wing is subject to pitching up-stop and the reduced frequency k (k=c/2U∞). Analysis of the pressure signal measured in the wind tunnel shows when the delta wing is subject to pitching-up the nondimensional spiral wave frequency at nominal incidence in post-breakdown is higher than that at corresponding static state and the bigger the k is, the higher the nondimensional spiral wave frequency is. The same conclusion is fitted with different sweep delta wing.

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