Transonic Reynolds Number and Bluntness Effects for a 65-deg Delta Wing

2003 ◽  
Author(s):  
James Luckring
Keyword(s):  
Reynolds Number ◽  
Delta Wing

Experimental Investigation on Blunt-Edged UTM Delta Wing VFE-2 Configurations at Low Reynolds Number

2018 ◽  
Vol 12 (3) ◽  
pp. 255
Author(s):  
Muhammad Zal Aminullah Daman Huri ◽  
Shabudin Bin Mat ◽  
Mazuriah Said ◽  
Shuhaimi Mansor ◽  
Md. Nizam Dahalan ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Delta Wing ◽  
Low Reynolds Number ◽  
Low Reynolds

Influence of Reynolds Number on Vortex Flow over a Non-slender Delta Wing

AIAA Journal ◽  
2010 ◽  
Vol 48 (12) ◽  
pp. 2831-2839 ◽  
Author(s):  
Lan Chen ◽  
Jinjun Wang ◽  
Lin-xuan Zuo ◽  
Li-Hao Feng
Keyword(s):  
Reynolds Number ◽  
Vortex Flow ◽  
Delta Wing

Reynolds Number Effects on Flow Topology Above Blunt-edged Delta Wing VFE-2 Configurations

2015 ◽  
Author(s):  
Mazuriah Said ◽  
Shabudin B. Mat ◽  
Shuhaimi Mansor ◽  
Ainullotfi Abdul-Latif ◽  
Tholudin Mat Lazim
Keyword(s):  
Reynolds Number ◽  
Delta Wing ◽  
Flow Topology ◽  
Reynolds Number Effects

Tuft Flow Visualisation on UTM-LST VFE-2 Delta Wing Model Configuration at High Angle of Attacks

2020 ◽  
Vol 17 (3) ◽  
pp. 8214-8223
Author(s):  
M. Said ◽  
M. Imai ◽  
S. Mat ◽  
M. N. Dahalan ◽  
S. Mansor ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Surface Pressure ◽  
Delta Wing ◽  
Measurement Techniques ◽  
Initial Point ◽  
Leading Edge ◽  
Flow Visualisation ◽  
Pressure Measurements ◽  
Wing Model ◽  
High Angles Of Attack

This paper reports on flow visualisation and surface pressure measurements over the upper surface of a blunt-edged delta wing model at high angles of attack. The flow structure above the upper surface of the blunt-edged delta wing was found to be different compared to delta wing with sharp leading edge. The flow becomes more complicated especially in the leading edge region of the wing. Currently, there is no data available to verify if the primary vortex could reach the apex of the wing when the angle of attack is further increased. Most prior experiments were performed at the angles of attack, α, below 23° with only a few experiments that had gone to α = 27°. These prior experiments and some CFD works stipulated that the attached flow continue to exist in the apex region of the delta wing even at very high angles of attack above 23°. In order to verify this hypothesis, several experiments at high angles of attack were conducted in Universiti Teknologi Malaysia Low Speed wind Tunnel (UTM–LST), using a specially constructed VFE2 wing model equipped with blunt leading edges. This series of experiments employed two measurement techniques; the first was the long tuft flow visualisation method, followed by surface pressure measurements. The experiments were performed at Reynolds numbers of 1.0×106 and 1.5×106.  During these experiments, several interesting flow characteristics were observed at high angles of attack, mainly that the flow became more sensitive to changes in Reynolds number and the angles of attack of the wing. When the Reynolds number increased from 1×106 to 1.5×106, the upstream progression of the initial point of the main vortex was relatively delayed compared to the sharp-edged delta wing. The experiments also showed that the flow continued to be attached in the apex region up to α = 27º.

scholarly journals Bluff bodies in deep turbulent boundary layers: Reynolds-number issues

2007 ◽  
Vol 571 ◽  
pp. 97-118 ◽  
Author(s):  
HEE CHANG LIM ◽  
IAN P. CASTRO ◽  
ROGER P. HOXEY
Keyword(s):  
Reynolds Number ◽  
Boundary Layers ◽  
Delta Wing ◽  
Body Height ◽  
Turbulent Boundary Layers ◽  
The Body ◽  
Bluff Bodies ◽  
Mean Flow ◽  
Order Of Magnitude ◽  
The Mean

It is generally assumed that flows around wall-mounted sharp-edged bluff bodies submerged in thick turbulent boundary layers are essentially independent of the Reynolds number Re, provided that this exceeds some (2–3) × 104. (Re is based on the body height and upstream velocity at that height.) This is a particularization of the general principle of Reynolds-number similarity and it has important implications, most notably that it allows model scale testing in wind tunnels of, for example, atmospheric flows around buildings. A significant part of the literature on wind engineering thus describes work which implicitly rests on the validity of this assumption. This paper presents new wind-tunnel data obtained in the ‘classical’ case of thick fully turbulent boundary-layer flow over a surface-mounted cube, covering an Re range of well over an order of magnitude (that is, a factor of 22). The results are also compared with new field data, providing a further order of magnitude increase in Re. It is demonstrated that if on the one hand the flow around the obstacle does not contain strong concentrated-vortex motions (like the delta-wing-type motions present for a cube oriented at 45° to the oncoming flow), Re effects only appear on fluctuating quantities such as the r.m.s. fluctuating surface pressures. If, on the other hand, the flow is characterized by the presence of such vortex motions, Re effects are significant even on mean-flow quantities such as the mean surface pressures or the mean velocities near the surfaces. It is thus concluded that although, in certain circumstances and for some quantities, the Reynolds-number-independency assumption is valid, there are other important quantities and circumstances for which it is not.

scholarly journals The leading-edge vortex of swift wing-shaped delta wings

2017 ◽  
Vol 4 (8) ◽  
pp. 170077 ◽  
Author(s):  
Rowan Eveline Muir ◽  
Abel Arredondo-Galeana ◽  
Ignazio Maria Viola
Keyword(s):  
Reynolds Number ◽  
Delta Wing ◽  
Leading Edge ◽  
Trailing Edge ◽  
Delta Wings ◽  
Leading Edge Vortex ◽  
Wing Model ◽  
Image Velocimetry ◽  
Edge Vortex ◽  
First Time

Recent investigations on the aerodynamics of natural fliers have illuminated the significance of the leading-edge vortex (LEV) for lift generation in a variety of flight conditions. A well-documented example of an LEV is that generated by aircraft with highly swept, delta-shaped wings. While the wing aerodynamics of a manoeuvring aircraft, a bird gliding and a bird in flapping flight vary significantly, it is believed that this existing knowledge can serve to add understanding to the complex aerodynamics of natural fliers. In this investigation, a model non-slender delta-shaped wing with a sharp leading edge is tested at low Reynolds number, along with a delta wing of the same design, but with a modified trailing edge inspired by the wing of a common swift Apus apus . The effect of the tapering swift wing on LEV development and stability is compared with the flow structure over the unmodified delta wing model through particle image velocimetry. For the first time, a leading-edge vortex system consisting of a dual or triple LEV is recorded on a swift wing-shaped delta wing, where such a system is found across all tested conditions. It is shown that the spanwise location of LEV breakdown is governed by the local chord rather than Reynolds number or angle of attack. These findings suggest that the trailing-edge geometry of the swift wing alone does not prevent the common swift from generating an LEV system comparable with that of a delta-shaped wing.

Effect of Streamwise Vortex Strength on Heat Transfer Enhancement of a Flat Plate

2016 ◽  
Author(s):  
Aditya Raman ◽  
Siddarth Chintamani ◽  
Brian H. Dennis
Keyword(s):  
Reynolds Number ◽  
Nusselt Number ◽  
Delta Wing ◽  
Angle Of Attack ◽  
Vortex Generator ◽  
Streamwise Vortex ◽  
Reynolds Numbers ◽  
Vortex Center ◽  
Polynomial Fit ◽  
The Right

This paper studies the variation of the streamwise vortex circulation resulting from a delta wing vortex generator. A delta wing vortex generator is employed in the common flow down configuration, this generates an anti-clockwise vortex over the right wing. Two different vortex generators with angle of attack 15° and 30° were considered in this study for a range of Reynolds numbers from 750 to 1500. The average Nusselt number was observed to increase with increasing Reynolds number and angle of attack. The circulation around the vortex core was calculated at different streamwise locations behind the vortex generator. The circulation of the vortex was observed to decrease in the down-stream direction. For a given Reynolds number and angle of attack, circulation at all streamwise locations was averaged in order to compare it with the trends observed by the averaged Nusselt number. The variation in averaged Circulation was identical to the Nusselt number. The vortex center locations were used to plot the trajectories by applying a least squares second order polynomial fit to the data.

Dynamics of revolving wings for various aspect ratios

2014 ◽  
Vol 748 ◽  
pp. 932-956 ◽  
Author(s):  
D. J. Garmann ◽  
M. R. Visbal
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Pressure Gradient ◽  
Centrifugal Force ◽  
Vortex Breakdown ◽  
Delta Wing ◽  
Strong Dependence ◽  
Tip Vortex ◽  
Aspect Ratios ◽  
Gradient Forces

AbstractHigh-fidelity, direct numerical simulations (DNSs) are conducted to examine the vortex structure and aerodynamic loading of unidirectionally revolving wings in quiescent fluid. Wings with aspect ratios $({\mathit{AR}}) = 1$, 2 and 4 are considered at a fixed root-based Reynolds number of 1000. Each wing is shown to generate a coherent leading-edge vortex (LEV) that remains in close proximity to the surface and provides persistent suction throughout the motion. Towards the tip, the LEV lifts off as an arch-like structure and reorients itself along the chord through its connection with the tip vortex. The substantial and sustained aerodynamic loads achieved during the motion saturate with aspect ratio resulting from the chordwise growth of the LEV along the span eventually becoming geometrically constrained by the trailing edge. Further, for ${\mathit{AR}}=4$, substructures develop in the feeding sheet of the LEV, which appear to directly correlate with the local, span-based Reynolds number achieved during rotation. The lower-aspect-ratio wings do not have sufficient spans for these transitional elements to manifest. In contrast, vortex breakdown, which occurs around midspan for each aspect ratio, shows a strong dependence on the spanwise pressure gradient established between the root and tip of the wing and not local Reynolds number. This independent development of shear-layer substructures and vortex breakdown parallels very closely with what has been observed in delta wing flow. Next, the centrifugal, Coriolis and pressure gradient forces are also analysed at several spanwise locations across each wing, and the centrifugal and pressure gradient forces are shown to be responsible for the spanwise flow above the wing. The Coriolis force is directed away from the surface at the base of the LEV, indicating that it is not a contributor to LEV attachment, which is contrary to previous hypotheses. Finally, as a means of emphasizing the importance of the centrifugal force on LEV attachment, the ${\mathit{AR}}=2$ wing is simulated with the addition of a source term in the governing equations to oppose and eliminate the centrifugal force near the surface. The initial formation and development of the LEV is unhindered by the absence of this force; however, later in the motion, the outboard lift-off of the LEV moves inboard. Without the opposing outboard-directed centrifugal force to keep the separation past midspan, the entire vortex eventually separates and moves away from the surface.

Sign in / Sign up

Export Citation Format

Share Document