Reynolds-number dependence of turbulence structures in a drag-reducing surfactant solution channel flow investigated by particle image velocimetry

2005 ◽  
Vol 17 (7) ◽  
pp. 075104 ◽  
Author(s):  
F.-C. Li ◽  
Y. Kawaguchi ◽  
T. Segawa ◽  
K. Hishida
Keyword(s):  
Reynolds Number ◽  
Particle Image Velocimetry ◽  
Channel Flow ◽  
Particle Image ◽  
Surfactant Solution ◽  
Turbulence Structures ◽  
Image Velocimetry ◽  
Reynolds Number Dependence

Measurement of Velocity Profiles of Laminar to Turbulent Water Flows in a Tube Using Particle Image Velocimetry

2004 ◽  
Author(s):  
Meredith R. Martin
Keyword(s):  
Reynolds Number ◽  
Particle Image Velocimetry ◽  
Particle Image ◽  
Glass Tube ◽  
Reynolds Numbers ◽  
Velocity Profiles ◽  
Reynolds Number Flow ◽  
Image Velocimetry ◽  
Dye Visualization ◽  
Number Flow

The transition from laminar to turbulent in-tube flow is studied in this paper. Water flow in a glass tube with an inside diameter of 21.7 mm was investigated by two methods. First, a dye visualization test using a setup similar to the 1883 experiment of Osborne Reynolds was conducted. For the dye visualization, Reynolds numbers ranging from approximately 1000 to 3500 were tested and the transition from laminar to turbulent flow was observed between Reynolds numbers of 2500 and 3500. For the second method, a particle image velocimetry (PIV) system was used to measure the velocity profiles of flow in the same glass tube at Reynolds numbers ranging from approximately 500 to 9000. The resulting velocity profiles were compared to theoretical laminar profiles and empirical turbulent power-law profiles. Good agreement was found between the lower Reynolds number flow and the laminar profile, and between the higher Reynolds number flow and turbulent power-law profile. In between the flow appeared to be in a transition region and deviated some between the two profiles.

Aerothermal Characterization of a Rotating Ribbed Channel at Engine Representative Conditions—Part I: High-Resolution Particle Image Velocimetry Measurements

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Ignacio Mayo ◽  
Gian Luca Gori ◽  
Aude Lahalle ◽  
Tony Arts
Keyword(s):  
Reynolds Number ◽  
Particle Image Velocimetry ◽  
Cross Section ◽  
Turbulence Intensity ◽  
Particle Image ◽  
Channel Cross Section ◽  
Recirculation Bubble ◽  
Rotation Numbers ◽  
Image Velocimetry ◽  
Static Conditions

The present work is part of a detailed aerothermal investigation in a model of a rotating internal cooling channel performed in a novel facility setup which allows test conditions at high rotation numbers (Ro). The test section is mounted on a rotating frame with all the required instrumentation, resulting in a high spatial resolution and accuracy. The channel has a cross section with an aspect ratio of 0.9 and a ribbed wall with eight ribs perpendicular to the main flow direction. The blockage of the ribs is 10% of the channel cross section, whereas the rib pitch-to-height ratio is 10. In this first part of the paper, the flow over the wall region between the sixth and seventh ribs in the symmetry plane is investigated by means of two-dimensional particle image velocimetry (PIV). Tests were carried out at a Reynolds number (Re) of 15,000 in static and rotating conditions, with a maximum Ro of 0.77. Results are in good agreement with the data present in literature at the same Reynolds number and with rotation numbers of 0 (static conditions) and 0.38 in a channel with the same geometry as in the present work. When Ro is increased from 0.38 to 0.77, the main velocity and turbulence fields show important changes. At a rotation number of 0.77, although the extension of the recirculation bubble after the sixth rib on the trailing side does not vary significantly, it covers the full inter-rib area on the leading side in the streamwise direction. The turbulence intensity on the leading side shows a low value with respect to the static case but roughly at the same level as in the lower Ro case. On the trailing side, the maximum value of the turbulence intensity slightly decreases from Ro  = 0.38 to Ro  = 0.77, the wall shear layer is restabilized along the second half of the pitch due to the high rotation, and the secondary flows are redistributed causing spanwise vortex compression. The observed result is the rapid decay of turbulent fluctuations in the second half of the inter-rib area.

Water Synthetic Jet Driven by a Piezoelectric Actuator – LIF and PIV Experiments

2015 ◽  
Vol 1104 ◽  
pp. 45-50 ◽  
Author(s):  
Zuzana Broučková ◽  
Shu Shen Hsu ◽  
An Bang Wang ◽  
Zdeněk Trávníček
Keyword(s):  
Reynolds Number ◽  
Particle Image Velocimetry ◽  
Piezoelectric Actuator ◽  
Particle Image ◽  
Three Dimensional ◽  
Laser Induced Fluorescence ◽  
Synthetic Jet ◽  
Fluid Exchange ◽  
Image Velocimetry ◽  
Surrounding Fluid

A synthetic jet (SJ) is a fluid jet flow generated from fluid oscillations during a periodical fluid exchange between an actuator cavity and surrounding fluid. A water synthetic jet was generated from submerged piezoelectric-driven SJ actuator. The actuator slot width was 0.36 mm. The experiments were performed using laser induced fluorescence (LIF) flow visualization and particle image velocimetry (PIV) techniques, both in a phase locked setup. The LIF visualization was used to demonstrate three-dimensional nature of the SJ formation process and to estimate SJ velocity. The PIV experiment quantified SJ velocity cycles in chosen plans. The driven frequency was adjusted near the resonance at approximately 46 Hz. It was evaluated theoretically and confirmed experimentally by means of LIF visualization. The time-mean orifice velocity and the Reynolds number were estimated asU0= 0.07–0.10 m/s andRe= 100–150, respectively.

scholarly journals The PIV study of air flow past the counter-swirler 53983

2018 ◽  
Vol 168 ◽  
pp. 05004 ◽  
Author(s):  
Daniel Duda
Keyword(s):  
Reynolds Number ◽  
Particle Image Velocimetry ◽  
Shear Layer ◽  
Particle Image ◽  
Contact Region ◽  
Air Flow ◽  
Swirling Jets ◽  
Flow Past ◽  
Image Velocimetry ◽  
Band Pass

PIV (particle image velocimetry) measurement of the air flow past a counter-swirler 53983 (anticlockwise swirler surrounded by clockwise swirler) is performed. The measurement is focused to an area at the boundary between the inner swirling jet and the outer one rotating oppositely. The Reynolds number Re based on the inner swirler diameter ranged form 1.2·103 to 2.1·104. By using band pass filtering the shear layer and vortices in the contact region between counter-swirling jets is highlighted. The shear layer between these regions shortens and decays into vortices as Reynolds number increases.

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