scholarly journals An Experimental Study on Unsteady Jets. Observation on the Behaviour of the Tip of Unsteady Region and the Vortex Pair by Means of Flow Visualization.

1996 ◽  
Vol 16 (63) ◽  
pp. 266-271
Author(s):  
Tosihiko IKEDA ◽  
Tetsu NAGABAYASHI ◽  
Yoshiaki TSUCHIYA ◽  
Tadanobu NAGASAWA ◽  
Tyozi HORIKOSI
Keyword(s):  
Experimental Study ◽  
Flow Visualization ◽  
Vortex Pair ◽  
Unsteady Jets

Visualization of transition

1969 ◽  
Vol 38 (3) ◽  
pp. 473-480 ◽  
Author(s):  
F. X. Wortmann
Keyword(s):  
Boundary Layer ◽  
Experimental Study ◽  
Flow Visualization ◽  
Three Dimensional ◽  
Vortex Pair ◽  
Instability Mode ◽  
Vortex Pattern ◽  
Görtler Vortices ◽  
Instability Modes ◽  
Gortler Vortices

In an experimental study the development of transition downstream of Görtler vortices was investigated. With the tellurium method it was possible to distinguish beyond the Görtler vortices to successive instability modes. The first deforms the vortex pattern in a steady way and produces between each vortex pair boundary-layer profiles with two points of inflexion. When this has been established another instability mode starts, consisting of regular three-dimensional oscillations. By detailed flow visualization a nearly complete picture of the different flow patterns can be obtained.

An Experimental Study of Local Wall Shear Stress, Surface Static Pressure, and Flow Visualization Upstream, Alongside, and Downstream of a Blade Endwall Corner

1991 ◽  
Vol 113 (4) ◽  
pp. 626-632 ◽  
Author(s):  
A. K. Abdulla ◽  
R. K. Bhargava ◽  
R. Raj
Keyword(s):  
Experimental Study ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Flow Visualization ◽  
Static Pressure ◽  
Leading Edge ◽  
Chord Length ◽  
Corner Region ◽  
Wall Shear ◽  
Blade Leading Edge

The experimental study reported in this paper was performed to acquire information on the distribution of wall shear stress and surface static pressure in a blade endwall corner. The blade endwall corner region investigated was divided into three sections: 0.4 chord length upstream of the blade leading edge, inside the endwall corner region, and one chord length downstream of the blade trailing edge. The maximum increases in the values of wall shear stress were found to exist on the endwall, in the corner region, between the blade leading edge and the location of maximum blade thickness (≈ 140 percent maximum increase, compared to its far upstream value, at x/D = 6). Surface flow visualization defined the boundaries of the vortex system and provided information on the direction and magnitude of the wall shear stress. The acquired results indicated that the observed variations of wall shear stress and surface static pressure were significantly influenced by the interaction of secondary flows with pressure gradients induced by the presence of blade curvature.

scholarly journals Experimental study on flow visualization of hypersonic flat plate boundary layer

2015 ◽  
Vol 64 (1) ◽  
pp. 014704
Author(s):  
Fu Jia ◽  
Yi Shi-He ◽  
Wang Xiao-Hu ◽  
Zhang Qing-Hu ◽  
He Lin
Keyword(s):  
Boundary Layer ◽  
Experimental Study ◽  
Flow Visualization ◽  
Flat Plate ◽  
Plate Boundary ◽  
Flat Plate Boundary Layer

Synchronous Vortex Shedding (Vortex Pumping) Downstream of a Flat Plate Array

1999 ◽  
Vol 122 (1) ◽  
pp. 183-185 ◽  
Author(s):  
D. W. Guillaume ◽  
J. C. LaRue
Keyword(s):  
Flow Visualization ◽  
Vortex Pair ◽  
Flat Plates ◽  
Mean Velocity ◽  
Trailing Edges ◽  
The Mean ◽  
Plate Array ◽  
Adjacent Channels ◽  
Bounding Surfaces ◽  
Zero Time

Flow visualization and statistics, obtained downstream of an array of flat plates, are presented. Flow visualization shows that the mean separation between streaklines for the flow downstream of adjacent channels is negatively correlated. Consistent with this observation, the zero-time cross correlation of the fluctuating velocity between adjacent plates is negative. Vortices shed at the trailing edges of the bounding surfaces that form a channel in the plate array are in-phase, but they are nearly 180 deg out-of-phase with the vortices shed at the trailing edges of the bounding surfaces of adjacent channels. Relative to the mean velocity, the axial velocity on the midplane of the channel increased in the region between each pair of vortices. At downstream positions not near the vortex pair, the velocity on the midplane is relatively decreased. Hence, vortices shed at the trailing edges of the channel surfaces lead to “vortex pumping,” which is consistent with the negative correlation of the fluctuating velocity on the midplanes between adjacent channels. [S0098-2202(00)01701-6]

An Experimental Study of Streamwise Vortices in a Compressor Cascade

1988 ◽  
Author(s):  
Chen Fang ◽  
Chen Mao-Zhang ◽  
Jiang Hao-Kang
Keyword(s):  
Experimental Study ◽  
Vortex Pair ◽  
Secondary Vortex ◽  
Streamwise Vortices ◽  
Reynolds Stresses ◽  
Compressor Cascade ◽  
Suction Surface ◽  
Mean Velocity ◽  
Passage Vortex ◽  
Corner Vortex

An experimental study on the production and development of streamwise vortices in a compressor cascade is reported. At four locations inside and one location outside the blade passage, the mean velocity components, three turbulent intensities and three Reynolds stresses were measured with a “x” hot wire probe. The results obtained describe the flow structure in the corner between the end-wall and blade suction surface in detail. Besides a passage vortex within the passage, there exist a shed corner vortex pair and a secondary vortex pair in the corner. The characteristics of two vortex pairs were different from that of the passage vortex. The mechanism causing the shed corner vortex pair and secondary vortex pair and the effect of these vortices on the cascade losses are discussed.

Unsteady Jets in Crossflow

Volume 4 ◽  
2004 ◽  
Author(s):  
K. B. M. Q. Zaman
Keyword(s):  
Shear Layer ◽  
Perturbation Technique ◽  
Cross Flow ◽  
Vortex Pair ◽  
Perturbation Techniques ◽  
Mechanical Perturbation ◽  
Unsteady Jets ◽  
Counter Rotating Vortex Pair ◽  
Vortex Systems ◽  
Ongoing Experiment

The effect of periodic perturbation on a jet in a cross-flow (JICF) is reviewed. In the first part of the paper, flow visualization results from several past works are discussed. Beginning with a description of the characteristic vortex systems of a JICF it is shown that specific perturbation techniques work by organizing and intensifying specific vortex systems. Oscillatory blowing works primarily through an organization of the shear layer vortices. A mechanical perturbation technique is found to organize the wake vortices. In the second part of the paper, results of an ongoing experiment involving another mechanical perturbation technique are discussed. It involves two tabs at the orifice exit whose asymmetry in placement is reversed periodically. It directly modulates the counter-rotating vortex pair (CVP). Effects of the perturbation for an array of three adjacent orifices are explored. The flowfield data show an improvement in mixing compared to the unperturbed case.

Sign in / Sign up

Export Citation Format

Share Document