scholarly journals Flow visualization of vortex structure in a pulsed rectangular jet

2008 ◽  
Vol 11 (2) ◽  
pp. 125-132 ◽  
Author(s):  
S. Iio ◽  
K. Takahashi ◽  
Y. Haneda ◽  
T. Ikeda
Keyword(s):  
Flow Visualization ◽  
Vortex Structure ◽  
Rectangular Jet

Three-dimensional Vortex structure of Rectangular Jet with Tapered Triangular Tubes at Nozzle Four Corners

2021 ◽  
Vol 2021.58 (0) ◽  
pp. F023
Author(s):  
Naoki KAJITANI ◽  
Takahiro KIWATA ◽  
Takaaki KONO ◽  
Nobuyoshi KOMATSU ◽  
Riku OUCHI
Keyword(s):  
Vortex Structure ◽  
Three Dimensional ◽  
Rectangular Jet ◽  
Four Corners

Experimental Analysis of Opposing Flow in Mixed Convection in a Channel With an Open Cavity Below

2005 ◽  
Author(s):  
Oronzio Manca ◽  
Sergio Nardini ◽  
Kambiz Vafai
Keyword(s):  
Reynolds Number ◽  
Mixed Convection ◽  
Flow Visualization ◽  
Vortex Structure ◽  
Open Cavity ◽  
Forced Flow ◽  
Heated Wall ◽  
Heated Plate ◽  
Thermal Plume ◽  
Recirculation Flow

In this paper mixed convection in an open cavity with a heated wall bounded by a horizontal unheated plate is investigated experimentally. The cavity has the heated wall on the opposite side of the forced inflow. The results are reported in terms of wall temperature profiles of the heated wall and flow visualization for Reynolds number (Re) from 100 to 2000 and Richardson number (Ri) in the range 4.3–6400; the ratio between the length and the height of cavity (L/D) is in the range 0.5–2.0 and the ratio between the channel and cavity height (H/D) is equal to 1.0. The present results show that at the lowest investigated Reynolds number the surface temperatures are lower than the corresponding surface temperature for Re = 2000, at same the ohmic heat flux. The flow visualization points out that for Re = 1000 there are two nearly distinct fluid motions: a parallel forced flow in the channel and a recirculation flow inside the cavity. For Re = 100 the effect of a stronger buoyancy determines a penetration of thermal plume from the heated plate wall into the upper channel. Moreover, the flow visualization points out that for lower Reynolds numbers the forced motion penetrates inside the cavity and a vortex structure is adjacent to the unheated vertical plate. At higher Reynolds number the vortex structure has a larger extension at same L/D value.

Flow visualization of vortex structure of an excited coaxial jet

2001 ◽  
Vol 4 (1) ◽  
pp. 99-107 ◽  
Author(s):  
T. Kiwata ◽  
A. Okajima ◽  
S. Kimura
Keyword(s):  
Flow Visualization ◽  
Vortex Structure

0632 Vortex Structure in an Excited Rectangular Jet

2013 ◽  
Vol 2013 (0) ◽  
pp. _0632-01_-_0632-02_
Author(s):  
Megumi TSUTSUI ◽  
Yusuke KATAYAMA ◽  
Shouishiro IIO
Keyword(s):  
Vortex Structure ◽  
Rectangular Jet

313 Effect of Flow Pulsation on the Vortex Structure in a Rectangular Jet(1)

2007 ◽  
Vol 2007 (0) ◽  
pp. _313-a_
Author(s):  
Shouichiro Iio ◽  
Kiyoshi Takahashi ◽  
Toshihiko Ikeda
Keyword(s):  
Vortex Structure ◽  
Flow Pulsation ◽  
Rectangular Jet

0512 Three-dimensional Vortex Structure in a Rectangular Jet Controlled by Sinusoidal Excitation

2012 ◽  
Vol 2012.49 (0) ◽  
pp. 051201-051202
Author(s):  
Shinnosuke TABUCHI ◽  
Keisuke MATSUMOTO ◽  
Shouichiro IIO ◽  
Yoshiaki HANEDA ◽  
Toshihiko IKEDA
Keyword(s):  
Vortex Structure ◽  
Three Dimensional ◽  
Rectangular Jet ◽  
Sinusoidal Excitation

scholarly journals Structure of the vortex wake in hovering Anna's hummingbirds ( Calypte anna )

2013 ◽  
Vol 280 (1773) ◽  
pp. 20132391 ◽  
Author(s):  
M. Wolf ◽  
V. M. Ortega-Jimenez ◽  
R. Dudley
Keyword(s):  
Flow Visualization ◽  
Vortex Structure ◽  
Force Production ◽  
Vortex Rings ◽  
Vortex Wake ◽  
Secondary Vortex ◽  
Single Vortex ◽  
Discrete Vortex ◽  
Weight Support ◽  
Calypte Anna

Hummingbirds are specialized hoverers for which the vortex wake has been described as a series of single vortex rings shed primarily during the downstroke. Recent findings in bats and birds, as well as in a recent study on Anna's hummingbirds, suggest that each wing may shed a discrete vortex ring, yielding a bilaterally paired wake. Here, we describe the presence of two discrete rings in the wake of hovering Anna's hummingbirds, and also infer force production through a wingbeat with contributions to weight support. Using flow visualization, we found separate vortices at the tip and root of each wing, with 15% stronger circulation at the wingtip than at the root during the downstroke. The upstroke wake is more complex, with near-continuous shedding of vorticity, and circulation of approximately equal magnitude at tip and root. Force estimates suggest that the downstroke contributes 66% of required weight support, whereas the upstroke generates 35%. We also identified a secondary vortex structure yielding 8–26% of weight support. Lift production in Anna's hummingbirds is more evenly distributed between the stroke phases than previously estimated for Rufous hummingbirds, in accordance with the generally symmetric down- and upstrokes that characterize hovering in these birds.

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