Instantaneous Measurement of Unsteady Three-Dimensional Velocity Fields With Photogrammetric PIV

2005 ◽  
Author(s):  
A. Schimpf ◽  
P. U. Thamsen
Keyword(s):  
Particle Image ◽  
Three Dimensional ◽  
Acoustic Emissions ◽  
Industrial Applications ◽  
Velocity Fields ◽  
Dimensional Structure ◽  
Two Phase ◽  
Image Velocimetry ◽  
Flow Phenomena ◽  
Set Up

Knowledge about the three-dimensional structure of a velocity field is important for understanding multiple flow phenomena associated with off design operation of pumps and turbines, acoustic emissions or two phase flow to name but a few. The measurement of three-dimensional unsteady velocity fields in industrial applications requires a robust, easy to use and universal measurement system. Existing 3D-3C-Particle-Image Velocimetry (PIV) Systems like Holographic PIV (HPIV) or Defocus-PIV suffer from restrictions to the optical accessibility of the volume to be investigated and a sophisticated optical set up. Hence the objective of this paper is to present the advanced Photogrammetric PIV (PPIV), a robust and easy to use 3D-3C-PIV system applicable to flows in areas with limited optical accessibility like in housings of rotary machines.

Different Modes of Gas Entrainment Through Bottom Discharge Branch by Using Three Dimensional Particle Image Velocimetry System

2007 ◽  
Author(s):  
Wael Fairouz Saleh ◽  
Ibrahim Galal Hassan
Keyword(s):  
Particle Image Velocimetry ◽  
Flow Structure ◽  
Particle Image ◽  
Three Dimensional ◽  
Industrial Applications ◽  
Particle Image Velocimetry System ◽  
Three Dimension ◽  
Two Phase ◽  
Mean Velocity ◽  
Image Velocimetry

The discharge of two-phase flow from a stratified region through single or multiple branches is an important process in many industrial applications including the pumping of fluid from storage tanks, shell-and-tube heat exchangers, and the fluid flow through small breaks in cooling channels of nuclear reactors during loss-of-coolant accidents (LOCA). Knowledge of the flow phenomena involved along with the quality and mass flow rate of the discharging stream(s) is necessary to adequately predict the different phenomena associated with the process. Particle Image Velocimetry (PIV) in three dimension was used to provide detailed measurements of the flow patterns involving distributions of mean velocity, vorticity field, and flow structure. The experimental investigation was carried out to simulate two phase discharge from a stratified region through branches located on a semi-circular wall configuration during LOCA scenarios. The semi-circular test section is in close dimensional resemblance with that of a CANDU header-feeder system, with branches mounted at orientation angles of zero, 45 and 90 degrees from the horizontal. The experimental data for the phase development (mean velocity, flow structure, etc.) was done during single discharge through the bottom branch from an air/water stratified region over a three selected Froude numbers. These measurements were used to describe the effect of outlet flow conditions on phase redistribution in headers and understand the entrainment phenomena.

Three-Dimensional Bubble Reconstruction in a Pipe Flow Using Shadow Technique

2002 ◽  
Author(s):  
Javier Ortiz-Villafuerte ◽  
Yassin A. Hassan ◽  
Toru Furukawa
Keyword(s):  
Pipe Flow ◽  
Particle Image ◽  
Three Dimensional ◽  
Bubbly Flows ◽  
Three Dimensional Reconstruction ◽  
Two Phase ◽  
Generalized Hough Transform ◽  
Image Velocimetry ◽  
Dimensional Reconstruction ◽  
Shadow Image Velocimetry

Two different three-dimensional reconstruction techniques for the shape of gas bubbles flowing in a liquid are presented. The first technique is based on the Dynamic Generalized Hough Transform Algorithm, and the second on the Metaball Model. These techniques are suitable for analysis of turbulent two-phase bubbly flows. Both techniques require at least two views of the bubble intended for three-dimensional reconstruction, and can be used in either stereoscopic or orthogonal camera setups. Once the reconstruction is accomplished, the bubble images can be accurately removed from the images acquired during Particle Image Velocimtery or Shadow Image Velocimetry measurements. After removing the bubble images from PIV images, a typical analysis of the liquid phase can be performed. This improves the accuracy of the statistical analysis of the parameters of each phase.

Momentum Distribution in the Wake of a Trapezoidal Pitching Panel

2016 ◽  
Vol 50 (5) ◽  
pp. 9-23 ◽  
Author(s):  
Rajeev Kumar ◽  
Justin T. King ◽  
Melissa A. Green
Keyword(s):  
Strouhal Number ◽  
Particle Image ◽  
Three Dimensional ◽  
Velocity Fields ◽  
Stereoscopic Particle Image Velocimetry ◽  
Vortex Rings ◽  
Vortex Identification ◽  
Freestream Velocity ◽  
Image Velocimetry ◽  
Thrust Production

AbstractThe oscillation of bioinspired fin-like panels in a uniform freestream flow creates chains of vortex rings, including streamwise segments that induce significant three-dimensional effects. With increasing Strouhal number, this wake structure induces flow with increasing nondimensional momentum, defined relative to the freestream velocity, in the downstream direction. This increase in relative momentum with increasing Strouhal number is consistent with greater nondimensional thrust production, which has been shown previously in the literature. These results were obtained via stereoscopic particle image velocimetry water tunnel experiments at Strouhal numbers ranging from 0.17 to 0.56 downstream of a continuously pitching trapezoidal panel. Features of the wake dynamics including spanwise compression, transverse expansion, transverse wake splitting or bifurcation, and wake breakdown are elucidated through analyses of phase-averaged as well as time-averaged velocity fields, in addition to common vortex identification methods.

Hydrodynamic Forces and DPIV on a Towed Pitching Foil

2014 ◽  
Author(s):  
R. Fernandez-Prats ◽  
F. J. Huera-Huarte
Keyword(s):  
Particle Image ◽  
Velocity Fields ◽  
Stepper Motor ◽  
Flow Structures ◽  
Caudal Peduncle ◽  
Hydrodynamic Loads ◽  
Caudal Fin ◽  
Image Velocimetry ◽  
Different Types ◽  
Set Up

More than 90% of the thrust generated by thunniform swimmers is known to be produced by the oscillation of their caudal fin, and the rest by their caudal peduncle. We have designed an experiment in which we can mimic, in a simplified manner, the kinematics of swimmers that mainly use their caudal fin for propulsion. The set-up consists of a rectangular foil attached to a shaft that is controlled by a stepper motor, and the whole assembly can be towed in still water at different controllable speeds. With this system we can study the effect of different types of pitching on the hydrodynamic loads and the performance of the propulsion system. By changing the type of foil, the effects of the flexibility in the propulsion can also be analysed. Hydrodynamic loads were measured with a 6-axes balance, and the flow structures were investigated using a Digital Particle Image Velocimetry (DPIV). Loads and DPIV velocity fields were acquired synchronously.

Flow Field Characterization at the Onset of Gas Entrainment in a Single Downward Discharge Using Particle Image Velocimetry

2007 ◽  
Vol 129 (12) ◽  
pp. 1565-1576 ◽  
Author(s):  
R. C. Bowden ◽  
I. G. Hassan
Keyword(s):  
Particle Image Velocimetry ◽  
Flow Field ◽  
Particle Image ◽  
Particle Image Velocimetry Data ◽  
Industrial Applications ◽  
Liquid Region ◽  
Two Phase ◽  
Gas Entrainment ◽  
Image Velocimetry ◽  
Side Flow

The incipience of two-phase flow in discharging branches from a stratified gas-liquid region has major implications in industrial applications where safety is of concern. An experimental investigation of the liquid side flow field at the onset of gas entrainment, in a single downward oriented discharging branch, was presented. Particle image velocimetry was used to measure the liquid side flow field in horizontal and vertical planes. Averaged velocity profiles were presented and demonstrated a highly radial flow. The particle image velocimetry data were validated using continuity and showed that the mass flow rate to be in the range of 10–25% of the expected value. Further, the vortex-free flow field assumption, used previously in the development of analytical and empirical models, was found to be reasonable.

Three Dimensional Velocity Measurements in an Automotive-Size Evaporator Using Particle Image Velocimetry

Volume 3 ◽  
2004 ◽  
Author(s):  
Steven P. O’Halloran ◽  
B. Terry Beck ◽  
Mohammad H. Hosni ◽  
Steven J. Eckels
Keyword(s):  
Particle Image Velocimetry ◽  
Single Phase ◽  
Particle Image ◽  
Three Dimensional ◽  
Flow Distribution ◽  
Stereoscopic Particle Image Velocimetry ◽  
Experimental Results ◽  
Two Phase ◽  
Volume Fractions ◽  
Image Velocimetry

The flow distribution inside of an evaporator is important to fully understand in order to optimize the design of the evaporator. A stereoscopic particle image velocimetry (PIV) system was used to measure single-phase water flow in a Plexiglas model of an automotive-sized evaporator. The evaporator is a “U-shape” type. Flow enters the inlet header and travels through a series of 26 parallel rectangular tubes. The tubes have a width of 15.5-mm, a flow gap (thickness) of 0.9-mm, and a length of 231-mm. The flow then enters the upper header and flows through another series of 26 parallel tubes to the outlet header. PIV measurements were only made within the headers due to the small size of the tubes, however detailed results were observed. In addition to the single-phase experimental results, computational fluid dynamics (CFD) simulations were conducted using the commercially available software Fluent, and the results compare well to the experimental results. Further work was conducted by injecting nitrogen into the flow to obtain two-phase flow under adiabatic conditions. Due to high vapor volume fractions, PIV could not be used for flow measurement, but a volume collection method was used to measure the flow of water through each tube. Significantly different flow distributions were observed at different inlet volume fractions of nitrogen and further investigation is underway.

PIV MEASUREMENTS AND NUMERICAL VALIDATION OF END-TO-SIDE ANASTOMOSIS

2010 ◽  
Vol 10 (01) ◽  
pp. 123-138 ◽  
Author(s):  
AMAL OWIDA ◽  
HUNG DO ◽  
WILLIAM YANG ◽  
YOS S. MORSI
Keyword(s):  
Particle Image ◽  
Three Dimensional ◽  
Quantitative Information ◽  
Velocity Fields ◽  
Flow Conditions ◽  
Ansys Software ◽  
Piv Measurements ◽  
Piv Technique ◽  
Image Velocimetry ◽  
Glass Model

In this article, particle image velocimetry (PIV) technique was used to determine the instantaneous velocity fields inside a model of end-to-side anastomosis under various physiological flow conditions. Using ANSYS software, a three-dimensional (3D) computational model at the peak systolic blood flow was simulated. The numerical and experimental results were presented and discussed in terms of velocity fields at various locations along the graft and the host artery. The numerical results were then compared with the experimental data and a large difference was found, which was attributed to the imperfection of manufacturing the glass model and measurements error associated with PIV. The findings indicated in general that the analysis at peak systole, steady flow could help in providing essential quantitative information of the hemodynamics in anastomotic artery.

scholarly journals Experimental Validation of Falling Liquid Film Models: Velocity Assumption and Velocity Field Comparison

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1205
Author(s):  
Ruiqi Wang ◽  
Riqiang Duan ◽  
Haijun Jia
Keyword(s):  
Experimental Data ◽  
Particle Image Velocimetry ◽  
Velocity Field ◽  
Experimental Validation ◽  
Particle Image ◽  
Velocity Fields ◽  
Number Range ◽  
Comparison Results ◽  
Image Velocimetry ◽  
Experimental Particle

This publication focuses on the experimental validation of film models by comparing constructed and experimental velocity fields based on model and elementary experimental data. The film experiment covers Kapitza numbers Ka = 278.8 and Ka = 4538.6, a Reynolds number range of 1.6–52, and disturbance frequencies of 0, 2, 5, and 7 Hz. Compared to previous publications, the applied methodology has boundary identification procedures that are more refined and provide additional adaptive particle image velocimetry (PIV) method access to synthetic particle images. The experimental method was validated with a comparison with experimental particle image velocimetry and planar laser induced fluorescence (PIV/PLIF) results, Nusselt’s theoretical prediction, and experimental particle tracking velocimetry (PTV) results of flat steady cases, and a good continuity equation reproduction of transient cases proves the method’s fidelity. The velocity fields are reconstructed based on different film flow model velocity profile assumptions such as experimental film thickness, flow rates, and their derivatives, providing a validation method of film model by comparison between reconstructed velocity experimental data and experimental velocity data. The comparison results show that the first-order weighted residual model (WRM) and regularized model (RM) are very similar, although they may fail to predict the velocity field in rapidly changing zones such as the front of the main hump and the first capillary wave troughs.

scholarly journals A computer-based approach for developing linamarase inhibitory agents

2020 ◽  
Vol 5 (7) ◽  
Author(s):  
Lucas Paul ◽  
Celestin N. Mudogo ◽  
Kelvin M. Mtei ◽  
Revocatus L. Machunda ◽  
Fidele Ntie-Kang
Keyword(s):  
Structure Elucidation ◽  
Three Dimensional ◽  
Data Bank ◽  
Competitive Inhibitor ◽  
Industrial Applications ◽  
Dimensional Structure ◽  
Full Understanding ◽  
The Poor ◽  
Computer Based ◽  
Inhibitory Agents

AbstractCassava is a strategic crop, especially for developing countries. However, the presence of cyanogenic compounds in cassava products limits the proper nutrients utilization. Due to the poor availability of structure discovery and elucidation in the Protein Data Bank is limiting the full understanding of the enzyme, how to inhibit it and applications in different fields. There is a need to solve the three-dimensional structure (3-D) of linamarase from cassava. The structural elucidation will allow the development of a competitive inhibitor and various industrial applications of the enzyme. The goal of this review is to summarize and present the available 3-D modeling structure of linamarase enzyme using different computational strategies. This approach could help in determining the structure of linamarase and later guide the structure elucidation in silico and experimentally.

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