Development of a High-Speed Three-Dimensional Flow Visualization Technique

AIAA Journal ◽  
2009 ◽  
Vol 47 (12) ◽  
pp. 2857-2865 ◽  
Author(s):  
Brian S. Thurow ◽  
Kyle P. Lynch
Keyword(s):  
Flow Visualization ◽  
High Speed ◽  
Three Dimensional ◽  
Visualization Technique ◽  
Three Dimensional Flow ◽  
Dimensional Flow

J0510102 Three dimensional flow visualization of wake structure behind of a twisted Savonius turbine

2015 ◽  
Vol 2015 (0) ◽  
pp. _J0510102--_J0510102-
Author(s):  
Susumu OSUKA ◽  
Hiroaki KOBAYASHI ◽  
Yoshihiko OISHI ◽  
Yuji TASAKA ◽  
Yuichi MURAI
Keyword(s):  
Flow Visualization ◽  
Three Dimensional ◽  
Three Dimensional Flow ◽  
Wake Structure ◽  
Dimensional Flow

Three-dimensional flow structure and string cavitation in a fuel injector and their effects on discharged liquid jet

2019 ◽  
Vol 22 (1) ◽  
pp. 243-256 ◽  
Author(s):  
Rubby Prasetya ◽  
Akira Sou ◽  
Junichi Oki ◽  
Akira Nakashima ◽  
Keiya Nishida ◽  
...  
Keyword(s):  
Vortex Ring ◽  
Flow Structure ◽  
High Speed ◽  
Three Dimensional ◽  
Liquid Jet ◽  
Fuel Injector ◽  
High Speed Imaging ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Stereo Particle Image Velocimetry

Two kinds of cavitation may occur in mini-sac type diesel injectors. The first is geometrical cavitation, which can usually be seen as a film-like structure in the nozzle. The second is the filament-like string cavitation. Both types of cavitation are known to affect fuel spray characteristics, although the effects of geometrical cavitation and that of string cavitation have not been individually clarified. Moreover, the mechanism behind string cavitation occurrence is still unclear. String cavitation usually occurs at low needle lift, which might indicate the existence of a vortex ring flow in the sac. However, because of the difficulty in precise flow measurement of the three-dimensional flow structure in the sac, the link between vortex ring flow and string cavitation occurrence in the sac has not been proven. In this study, high-speed imaging of string cavitation, geometrical cavitation, and discharged liquid jet of an enlarged three-hole mini-sac diesel fuel injector was conducted to individually clarify the effects of string cavitation and geometrical cavitation on the discharged liquid jet angle. Furthermore, tomographic–stereo particle image velocimetry was carried out on the sac. The experiments were conducted at two different needle lifts, to clarify the link between needle lifts and flow structure in the sac, as well as how it affects string cavitation occurrence and liquid jet angle. The results confirmed that at low needle lift, vortex ring flow forms in the sac, which may induce helical flow in the nozzle, resulting in a large jet angle. Vortex strength varies with time, and string cavitation occurs when the vortex is particularly strong. As a result, the magnitude of the jet angle increase at low needle lift is enhanced when string cavitation occurs. At high needle lift, flow pattern in the sac becomes relatively uniform, which makes it harder for string cavitation to form.

Three-dimensional flow visualization and vorticity dynamics in revolving wings

2013 ◽  
Vol 54 (1) ◽  
Author(s):  
Bo Cheng ◽  
Sanjay P. Sane ◽  
Giovanni Barbera ◽  
Daniel R. Troolin ◽  
Tyson Strand ◽  
...  
Keyword(s):  
Flow Visualization ◽  
Three Dimensional ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Vorticity Dynamics

scholarly journals Three-dimensional flow and lift characteristics of a hovering ruby-throated hummingbird

2014 ◽  
Vol 11 (98) ◽  
pp. 20140541 ◽  
Author(s):  
Jialei Song ◽  
Haoxiang Luo ◽  
Tyson L. Hedrick
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Leading Edge ◽  
Dynamics Simulation ◽  
Vertical Force ◽  
Imaging Data ◽  
High Speed Imaging ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Wake Interaction

A three-dimensional computational fluid dynamics simulation is performed for a ruby-throated hummingbird ( Archilochus colubris ) in hovering flight. Realistic wing kinematics are adopted in the numerical model by reconstructing the wing motion from high-speed imaging data of the bird. Lift history and the three-dimensional flow pattern around the wing in full stroke cycles are captured in the simulation. Significant asymmetry is observed for lift production within a stroke cycle. In particular, the downstroke generates about 2.5 times as much vertical force as the upstroke, a result that confirms the estimate based on the measurement of the circulation in a previous experimental study. Associated with lift production is the similar power imbalance between the two half strokes. Further analysis shows that in addition to the angle of attack, wing velocity and surface area, drag-based force and wing–wake interaction also contribute significantly to the lift asymmetry. Though the wing–wake interaction could be beneficial for lift enhancement, the isolated stroke simulation shows that this benefit is buried by other opposing effects, e.g. presence of downwash. The leading-edge vortex is stable during the downstroke but may shed during the upstroke. Finally, the full-body simulation result shows that the effects of wing–wing interaction and wing–body interaction are small.

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