Experimental Study of Very Low Aspect Ratio Wings in Slender Bodies

2012 ◽  
Author(s):  
M. A. Arevalo-Campillos ◽  
S. Tuling ◽  
L. Parras ◽  
C. del Pino ◽  
L. Dala
Keyword(s):  
Experimental Study ◽  
Aspect Ratio ◽  
Numerical Simulations ◽  
Water Channel ◽  
Vortex Sheet ◽  
The Body ◽  
Low Aspect Ratio ◽  
Moderate Reynolds Number ◽  
Slender Bodies ◽  
Low Aspect Ratio Wings

The dynamics of very low aspect ratio wings (or strakes) vortices in slender bodies are complex due to the interaction of the shed vortex sheet and the body vortex. For missiles at supersonic speeds these interactions are not easily predicted using engineering level tools. To shed some new light onto this problem, an experimental study in a water channel for moderate Reynolds number (Re = 1000) was performed for a 19D body and strake configuration with strakes having a span to body diameter ratio of 1.25. Comparisons to numerical simulations in supersonic flow are also performed. Flow visualisation has been carried out to characterize the vortex dynamics at different angles of attack; these being 11°, 16°, 22° and 27°. The comparison between a slender body without strakes and the body-strake configuration has given some key indicators in relation to the vortex position of the core. Furthermore, unsteady wing-body interference has been observed at angles of attack above 20° for both experimental and numerical simulations. Consequently, the average position of the vortex core is located at larger distances from the missile in comparison to the body without strakes. The numerical simulations show good correlation with the experimental tests even though the dynamic convective interactions between the body vortex and strake vortex sheet are not predicted.

Experimental study of vortex flow about low aspect ratio wings and circular cones at M = 2

1967 ◽  
Vol 2 (5) ◽  
pp. 74-79 ◽  
Author(s):  
V. I. Alferov ◽  
T. I. Okerblom ◽  
A. I. Sarantsev
Keyword(s):  
Experimental Study ◽  
Aspect Ratio ◽  
Vortex Flow ◽  
Low Aspect Ratio ◽  
Low Aspect Ratio Wings

Experimental Study on Vortex-Induced Vibration of Floating Circular Cylinders With Low Aspect Ratio

2014 ◽  
Author(s):  
Rodolfo T. Gonçalves ◽  
André L. C. Fujarra
Keyword(s):  
Experimental Study ◽  
Aspect Ratio ◽  
Water Channel ◽  
Circular Cylinders ◽  
Structural Damping ◽  
End Effects ◽  
Vortex Induced Vibration ◽  
Low Aspect Ratio ◽  
Aspect Ratios ◽  
Ratio Range

Experiments regarding vortex-induced vibration on floating circular cylinders with low aspect ratio were carried out in a recirculation water channel. The floating circular cylinders were elastic supported by a set of linear springs to provide low structural damping on the system. Eight different aspect ratios were tested, namely L/D = 0.2, 0.3, 0.4, 0.5, 0.75, 1.0, 1.5 and 2.0. These aspect ratios were selected to cover the aspect ratio range of the main offshore circular platforms, such as spar and monocolumn. The aims were understanding the VIM of such platforms; due to this, the cylinders were floating, or m* = 1. The range of Reynolds number covered 2,800 < Re < 55,400. The amplitude results showed a decrease in amplitude with decreasing aspect ratio in both directions. The frequency results confirm a different behavior for cylinders with L/D ≤ 0.5; in these cases, the cylinder free-end effects were predominant. The resonant behaviour was no longer observed for L/D ≤ 0.2. The decrease in Strouhal number with decreasing aspect ratio is also verified. All the results presented here complement the work presented previously for stationary circular cylinder with low aspect ratio presented by Gonçalves et al. (2013), Experimental Study on Flow around Circular Cylinders with Low Aspect Ratio, OMAE2013-10454.

Experimental Study on Vortex-Induced Vibration of Floating Circular Cylinders With Low Aspect Ratio and Different Free-End Corner Shapes

2018 ◽  
Author(s):  
Rodolfo T. Gonçalves ◽  
Keigo Sakata ◽  
Dennis M. Gambarine ◽  
Murilo M. Cicolin ◽  
Shinichiro Hirabayashi ◽  
...  
Keyword(s):  
Experimental Study ◽  
Aspect Ratio ◽  
Water Channel ◽  
Circular Cylinders ◽  
Structural Damping ◽  
End Effects ◽  
Vortex Induced Vibration ◽  
Low Aspect Ratio ◽  
End Conditions ◽  
Elastically Supported

Experiments regarding vortex-induced vibration (VIV) on floating circular cylinders with low aspect ratio, L/D = 0.5, and different free-end conditions were carried out in a recirculation water channel. The floating circular cylinders were elastically supported by a set of linear springs to provide low structural damping on the system. Four different free-end corner shape conditions were tested, namely r/R = 0.0, 0.25, 0.5 and 1.0; where r/R is the relation between chamfer rounding radius, r, and the radius of cylinder, R. These different free-end conditions were selected to promote changes in the structures shedding around the free end of the cylinder. The aims were to understand the free-end effects on the VIV of floating circular cylinders with very low aspect ratio. The range of Reynolds number covered 2,800 < Re < 55,400. All the results presented here complement the work presented previously for a floating circular cylinder with L/D = 2.0 by Gambarine et al. (2016) [6] - Experimental study of the influence of the free end effects on vortex-induced vibration of floating cylinder with low aspect of ratio, OMAE2016-54623. The present results showed that the amplitudes in both directions were the highest for the semi-sphere case, r/R = 1.0. The amplitudes were almost the same for the other radius values, 0.0 < r/R ≤ 0.5; in which the maximum amplitudes decreased with increasing the corner radius. A critical value, L/Dcrit = 0.5, in which only the free-end structures affect the VIV behavior of the cylinder piercing the free-surface could be stated. The conclusion was that the cylinder free-end affects the VIV behavior for cylinders with very low-aspect ratio.

Passive mitigation of roll stall for low aspect ratio wings

2013 ◽  
Vol 27 (9) ◽  
pp. 667-681 ◽  
Author(s):  
Matt Shields ◽  
Kamran Mohseni
Keyword(s):  
Aspect Ratio ◽  
Low Aspect Ratio ◽  
Low Aspect Ratio Wings
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