Measurement of three-dimensional velocity profiles using forward-scattering particle image velocimetry (FSPIV) and neural net pattern recognition

1995 ◽  
Author(s):  
Ben Ovryn ◽  
Ted Wright ◽  
John D. Khaydarov
Keyword(s):  
Pattern Recognition ◽  
Particle Image Velocimetry ◽  
Particle Image ◽  
Three Dimensional ◽  
Velocity Profiles ◽  
Forward Scattering ◽  
Neural Net ◽  
Image Velocimetry

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.

Particle Image Velocimetry Measurements of Turbulent Jets Issuing From Twin Elliptic Nozzles With Various Orientations

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Ella Marie Morris ◽  
Neelakash Biswas ◽  
Seyed Sobhan Aleyasin ◽  
Mark Francis Tachie
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Symmetry Plane ◽  
Velocity Profiles ◽  
Equivalent Diameter ◽  
Linear Contraction ◽  
Turbulent Characteristics ◽  
Image Velocimetry ◽  
Nozzle Orientation ◽  
Minor Plane

Abstract The effects of nozzle orientation on the mixing and turbulent characteristics of elliptical free twin jets were studied experimentally. The experiments were conducted using modified contoured nozzles with a sharp linear contraction. The centers of the nozzle pair had a separation ratio of 5.5. Two nozzle configurations were tested, twin nozzles oriented along the minor plane (Twin_Minor) and twin nozzles oriented along the major plane (Twin_Major) and the results were compared with a single jet. In each case, the Reynolds number based on the maximum jet velocity and the equivalent diameter was 10,000. A planar particle image velocimetry (PIV) system was used to measure the velocity field in the jet symmetry plane. It was observed that the velocity decay rate is not sensitive to nozzle orientation. However, close to the jet exit, the spread rate was highest in the minor plane. In addition, contour plots of swirling strength, Reynolds shear stress and turbulent intensities revealed significant differences between the minor and major planes. Velocity profiles showed little variation close to the jet exit, while further downstream the variations between the velocity profiles were more pronounced between the major and minor planes.

Application of Long-Distance Forward-Scattering Particle Image Velocimetry in Micro-Scale Turbulent Jet Flow Tests

2006 ◽  
Author(s):  
Lichuan Gui ◽  
Bernard J. Jansen ◽  
John M. Seiner
Keyword(s):  
Particle Image Velocimetry ◽  
High Speed ◽  
Particle Image ◽  
Forward Scattering ◽  
Particle Image Velocimetry System ◽  
Central Plane ◽  
Long Distance ◽  
Micro Scale ◽  
Air Jet ◽  
Image Velocimetry

A new particle image velocimetry system is applied to measure turbulent air jet flows from a micro-scale nozzle. The applied MPIV system includes a long-distance microscope that enables not only a long working distance, but also a forward-scattering optical setup. By using a high repeating rate Nd:YAG laser and an advanced digital camera, particle image recordings can be captured at 60 fps, i.e. 30 PIV recording pairs per second, with an interframing time of 180 ns, so that a high-speed flow measurement is enabled in micro scale. Measurements were conducted in the central plane of an air jet from a nozzle of 500 μm in diameter at flow velocity up to 110 m/s. Mean velocity and Reynolds stress distributions were determined with statistical analyses of thousands of instantaneous velocity maps.

scholarly journals Simultaneous Measurement of Free Surface Elevation and Three-Component Velocity Field Around a Translating Surface-Piercing Foil

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
James Schock ◽  
Jason Dahl
Keyword(s):  
Particle Image Velocimetry ◽  
Free Surface ◽  
Velocity Field ◽  
Numerical Methods ◽  
Flow Field ◽  
Particle Image ◽  
Laser Sheet ◽  
Three Dimensional ◽  
Dynamic Mode ◽  
Image Velocimetry

Two methods are investigated to simultaneously obtain both three-dimensional (3D) velocity field and free surface elevations (FSEs) measurements near a surface piercing foil, while limiting the equipment. The combined velocity field and FSE measurements are obtained specifically for the validation of numerical methods requiring simultaneous field data and free surface measurements for a slender body shape. Both methods use stereo particle image velocimetry (SPIV) to measure three component velocities in the flow field and both methods use an off the shelf digital camera with a laser intersection line to measure FSEs. The first method is performed using a vertical laser sheet oriented parallel to the foil chord line. Through repetition of experiments with repositioning of the laser, a statistical representation of the three-dimensional flow field and surface elevations is obtained. The second method orients the vertical laser sheet such that the foil chord line is orthogonal to the laser sheet. A single experiment is performed with this method to measure the three-dimensional three component (3D3C) flow field and free surface, assuming steady flow conditions, such that the time dimension is used to expand the flow field in 3D space. The two methods are compared using dynamic mode decomposition and found to be comparable in the primary mode. Utilizing these methods produces results that are acceptable for use in numerical methods verification, at a fraction of the capital and computing cost associated with two plane or tomographic particle image velocimetry (PIV).

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