MRI investigation and complementary numerical simulations of flow-through random bead packings with low aspect ratio

2005 ◽  
Vol 23 (2) ◽  
pp. 369-370 ◽  
Author(s):  
Claudia Heinen ◽  
Joachim Tillich ◽  
Hans Buggisch ◽  
Thomas Zeiser ◽  
Hannsjörg Freund
Keyword(s):  
Aspect Ratio ◽  
Numerical Simulations ◽  
Low Aspect Ratio ◽  
Flow Through

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.

scholarly journals Numerical Simulations of the Transient Flow Response of a 3D, Low-Aspect-Ratio Wing to Pulsed Actuation

2011 ◽  
Author(s):  
Guillaume Brès ◽  
Ehab Fares ◽  
David Williams ◽  
Tim Colonius
Keyword(s):  
Aspect Ratio ◽  
Numerical Simulations ◽  
Transient Flow ◽  
Low Aspect Ratio ◽  
Flow Response

scholarly journals The effect of aspect ratio on adhesion and stiffness for soft elastic fibres

2011 ◽  
Vol 8 (61) ◽  
pp. 1166-1175 ◽  
Author(s):  
Burak Aksak ◽  
Chung-Yuen Hui ◽  
Metin Sitti
Keyword(s):  
Numerical Analysis ◽  
Aspect Ratio ◽  
Numerical Simulations ◽  
Adhesive Strength ◽  
Polyurethane Elastomer ◽  
Rigid Surface ◽  
Elastic Fibres ◽  
Low Aspect Ratio ◽  
Adhesive Interface

The effect of aspect ratio on the pull-off stress and stiffness of soft elastic fibres is studied using elasticity and numerical analysis. The adhesive interface between a soft fibre and a smooth rigid surface is modelled using the Dugdale–Barenblatt model. Numerical simulations show that, while pull-off stress increases with decreasing aspect ratio, fibres get stiffer. Also, for sufficiently low aspect ratio fibres, failure occurs via the growth of internal cracks and pull-off stress approaches the intrinsic adhesive strength. Experiments carried out with various aspect ratio polyurethane elastomer fibres are consistent with the numerical simulations.

scholarly journals Numerical Simulations of Natural and Actuated Flow over a 3-D, Low-Aspect-Ratio Airfoil

2010 ◽  
Author(s):  
Guillaume Brès ◽  
David Williams ◽  
Tim Colonius
Keyword(s):  
Aspect Ratio ◽  
Numerical Simulations ◽  
Low Aspect Ratio

Unsteady Analysis of Inter-Rows Stator-Rotor Spacing Effects on a Transonic, Low-Aspect Ratio Turbine

2015 ◽  
Author(s):  
Etienne Tang ◽  
Gilles Leroy ◽  
Mickaël Philit ◽  
Jacques Demolis
Keyword(s):  
Experimental Data ◽  
Aspect Ratio ◽  
High Pressure Turbine ◽  
Low Aspect Ratio ◽  
Spacing Effects ◽  
Air Turbine ◽  
Flow Features ◽  
Aerodynamic Performances ◽  
Flow Through ◽  
Transonic Turbine

The aerodynamic performances of an axial turbine are affected by the distance between the stator and the rotor. Previous studies have shown different trends, depending mainly on whether the turbine is subsonic or not. The present paper aims at improving the understanding of the effect of rows spacing on the flow through a transonic turbine. A one-stage, low aspect ratio, high pressure turbine case is investigated using CFD. Steady and unsteady phase-lagged RANS computations are performed on this configuration with different inter-blade rows distances. The results are successfully compared with experimental data from a cold air turbine rig. Entropy production balances are used to emphasize the main loss areas and the loss variations caused by changes in inter-blade rows distance. Two techniques are compared for computing these balances, and one of them appears to perform much better. The flow features causing these losses are then identified. Finally, an optimal inter-rows spacing is found. It is a compromise between the losses created by strong stator-rotor interactions at small inter-rows gaps and the losses generated at the endwalls in the inter-rows space at large distances.

Development of an Ion Beam Probe System for Potential Measurement in the Low Aspect-Ratio Torus Experiment Device

2012 ◽  
Vol 132 (7) ◽  
pp. 567-573
Author(s):  
Hitoshi Tanaka ◽  
Shota Omi ◽  
Jun Katsuma ◽  
Yurie Yamamoto ◽  
Masaki Uchida ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Ion Beam ◽  
Potential Measurement ◽  
Low Aspect Ratio ◽  
Probe System ◽  
Experiment Device

Numerical study of a high-work low-aspect-ratio turbine stage

1995 ◽  
Author(s):  
Suk Kim ◽  
Robert Stubbs
Keyword(s):  
Aspect Ratio ◽  
Numerical Study ◽  
Turbine Stage ◽  
Low Aspect Ratio ◽  
High Work
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