scholarly journals Vortex Breakdown Control by the Plasma Swirl Injector

2021 ◽  
Vol 11 (12) ◽  
pp. 5537
Author(s):  
Gang Li ◽  
Xi Jiang ◽  
Wei Du ◽  
Jinhu Yang ◽  
Cunxi Liu ◽  
...  
Keyword(s):  
Particle Image ◽  
Vortex Breakdown ◽  
Physical Phenomenon ◽  
Efficient Utilization ◽  
Plasma Actuation ◽  
Breakdown Region ◽  
Image Velocimetry ◽  
Wide Range ◽  
Measurement Results ◽  
Swirl Injector

Vortex breakdown, observed in swirling flows, is an interesting physical phenomenon relevant to a wide range of engineering applications, including aerodynamics and combustion. The concept of using a plasma swirler to control vortex breakdown was proposed and tested in this study. The effect of plasma actuation on controlling the onset and development of the vortex breakdown was captured by particle image velocimetry. Flowfield measurement results suggested that, by varying the strength of the plasma actuation, the location and size of the vortex breakdown region was controlled effectively. The plasma swirl injector offers a method for optimal control and efficient utilization of vortex breakdown. The method being proposed here may represent an attractive way of controlling vortex breakdown using a small amount of energy input, without a moving or intrusive part.

Simultaneous Measurement of Temperature and Velocity in Turbulent Buoyant Plume by Combined LIF and PIV Technique

2006 ◽  
Author(s):  
Yoshie Watanabe ◽  
Yuji Hashizume ◽  
Nobuyuki Fujisawa
Keyword(s):  
Simultaneous Measurement ◽  
Particle Image ◽  
Fluorescent Dyes ◽  
Buoyant Plume ◽  
Thermal Flow ◽  
Piv Technique ◽  
Image Velocimetry ◽  
Wide Range ◽  
High Temperature Sensitivity ◽  
Surrounding Fluid

An experimental technique for simultaneous measurement of temperature and velocity in a thermal flow is described. This technique is based on the two-color laser-induced fluorescence technique combined with the particle image velocimetry. Illumination is provided from Nd:YAG laser and the fluorescent dyes are chosen as Rhodamine B and Fluorescent Sodium, which combination allows the accurate velocity measurement in a wide range of flow velocity and high temperature sensitivity in temperature measurement. The measurement of temperature and velocity in turbulent buoyant plume is carried out by this method, and the structure of the plume is studied in connection with the entrainment of surrounding fluid at the interface.

Microfluidics Supporting an Optical Instrument for Multimodal Single Cell Biomechanics

2007 ◽  
Author(s):  
Nathalie Ne`ve ◽  
James K. Lingwood ◽  
Shelley R. Winn ◽  
Derek C. Tretheway ◽  
Sean S. Kohles
Keyword(s):  
Particle Image Velocimetry ◽  
Hydrostatic Pressure ◽  
Single Cell ◽  
Optical Tweezers ◽  
Particle Image ◽  
Single Cells ◽  
Optical Instrument ◽  
Image Velocimetry ◽  
Wide Range ◽  
Induced Stresses

Interfacing a novel micron-resolution particle image velocimetry and dual optical tweezers system (μPIVOT) with microfluidics facilitates the exposure of an individual biologic cell to a wide range of static and dynamic mechanical stress conditions. Single cells can be manipulated in a sequence of mechanical stresses (hydrostatic pressure variations, tension or compression, as well as shear and extensional fluid induced stresses) while measuring cellular deformation. The unique multimodal load states enable a new realm of single cell biomechanical studies.

Experimental Analysis of the Near Wake from a Ducted Thruster at True and Near Bollard Pull Conditions Using Stereo Particle Image Velocimetry (SPIV)

2005 ◽  
Vol 127 (3) ◽  
pp. 191-196 ◽  
Author(s):  
S. El Lababidy ◽  
N. Bose ◽  
P. Liu ◽  
D. Walker ◽  
F. Di Felice
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Practical Interest ◽  
Stereoscopic Particle Image Velocimetry ◽  
Wake Flow ◽  
Hydrodynamic Characteristics ◽  
Near Wake ◽  
Image Velocimetry ◽  
Wide Range ◽  
Marine Applications

Thrusters working at low advance coefficients are employed in a wide range of offshore and marine applications on Floating, Production, Storage, and Offloading (FPSO) systems; shuttle tankers; tug boats; and mobile offshore units. Therefore, an understanding of the flow around the thrusters is of great practical interest. Despite this interest, there is lack of knowledge in the description of the hydrodynamic characteristics of a ducted thruster’s wake at bollard pull and low advance coefficient values. This work was aimed at providing detailed data about the hydrodynamic characteristics of a Dynamic Positioning (DP) thruster near wake flow at different low advance coefficient values. Wake measurements were made during cavitation tunnel tests carried out on a ducted propeller model at the Italian Ship Model Basin (INSEAN), Rome, Italy. Through these experiments, the DP thruster near wake velocity components at different downstream axial planes, up to 1.5 diameters downstream, were obtained using a Stereoscopic Particle Image Velocimetry (SPIV) system. These experiments were carried out at different advance coefficient (J) values [bollard pull (J=0), J=0.4 and J=0.45].

An Experimental Investigation of the Permeability in Porous Chip Formed by Micropost Arrays Based on Microparticle Image Velocimetry and Micromanometer Measurements

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Haoli Wang ◽  
Pengwei Wang
Keyword(s):  
Cross Section ◽  
Particle Image ◽  
Brinkman Equation ◽  
Two Dimensional ◽  
Micro Particle Image Velocimetry ◽  
Micro Piv ◽  
Image Velocimetry ◽  
Measurement Results ◽  
Microparticle Image Velocimetry ◽  
The Cross

Measurements of velocity and pressure differences for flows in porous chip fabricated with micropost arrays arranged in square pattern were implemented by using micro-particle image velocimetry (micro-PIV) and high precision micromanometer. Based on the measurement results, the permeability was solved by Brinkman equation under the averaged velocities over the cross section, two-dimensional velocities on the center plane of the microchannels, and the averaged velocities on the center plane considering the effect of depth of correlation (DOC), respectively. The experimental results indicate that the nondimensional permeability based on different velocities satisfies the Kozeny–Carman (KC) equation. The Kozeny factor is taken as 40 for the averaged velocity over the cross section and 15 for two kinds of center velocities based on the micropost array of this study, respectively. The permeability calculated by the velocities on the center plane is greater than that by the averaged velocity over the cross section.

scholarly journals Quantitative flow analysis around aquatic animals using laser sheet particle image velocimetry

1995 ◽  
Vol 198 (2) ◽  
pp. 283-294 ◽  
Author(s):  
E Stamhuis ◽  
J Videler
Keyword(s):  
Particle Image Velocimetry ◽  
Flow Field ◽  
Particle Image ◽  
Light Sheet ◽  
Flow Fields ◽  
Image Correlation ◽  
Dissipated Energy ◽  
Two Dimensional ◽  
Image Velocimetry ◽  
Wide Range

Two alternative particle image velocimetry (PIV) methods have been developed, applying laser light sheet illumination of particle-seeded flows around marine organisms. Successive video images, recorded perpendicular to a light sheet parallel to the main stream, were digitized and processed to map the flow velocity in two-dimensional planes. In particle tracking velocimetry (PTV), displacements of single particles in two subsequent images were determined semi-automatically, resulting in flow diagrams consisting of non-uniformly distributed velocity vectors. Application of grid-cell averaging resulted in flow field diagrams with uniform vector distribution. In sub-image correlation PIV (SCPIV), repetitive convolution filtering of small sub-areas of two subsequent images resulted in automatic determination of cross-correlation peaks, yielding flow field diagrams with regularly spaced velocity vectors. In both PTV and SCPIV, missing values, caused by incomplete particle displacement information in some areas of the images or due to rejection of some erroneous vectors by the vector validation procedure, were interpolated using a two-dimensional spline interpolation technique. The resultant vector flow fields were used to study the spatial distribution of velocity, spatial acceleration, vorticity, strain and shear. These flow fields could also be used to test for flow in the third dimension by studying the divergence, and to detect the presence and location of vortices. The results offer detailed quantitative descriptions of the flow morphology and can be used to assess dissipated energy. The versatile character of the technique makes it applicable to a wide range of fluid mechanical subjects within biological research. So far it has been successfully applied to map the flow around swimming copepods, fish larvae and juvenile fish and the ventilation current of a tube-living shrimp.

scholarly journals A ctenophore (comb jelly) employs vortex rebound dynamics and outperforms other gelatinous swimmers

2019 ◽  
Vol 6 (3) ◽  
pp. 181615 ◽  
Author(s):  
Brad J. Gemmell ◽  
Sean P. Colin ◽  
John H. Costello ◽  
Kelly R. Sutherland
Keyword(s):  
High Speed ◽  
Particle Image ◽  
Solid Wall ◽  
Fluid Dynamic ◽  
Propulsion Systems ◽  
Vortex Interactions ◽  
Image Velocimetry ◽  
Wide Range ◽  
Rebound Phenomenon ◽  
Propulsive Mechanism

Gelatinous zooplankton exhibit a wide range of propulsive swimming modes. One of the most energetically efficient is the rowing behaviour exhibited by many species of schyphomedusae, which employ vortex interactions to achieve this result. Ctenophores (comb jellies) typically use a slow swimming, cilia-based mode of propulsion. However, species within the genus Ocyropsis have developed an additional propulsive strategy of rowing the lobes, which are normally used for feeding, in order to rapidly escape from predators. In this study, we used high-speed digital particle image velocimetry to examine the kinematics and fluid dynamics of this rarely studied propulsive mechanism. This mechanism allows Ocyropsis to achieve size-adjusted speeds that are nearly double those of other large gelatinous swimmers. The investigation of the fluid dynamic basis of this escape mode reveals novel vortex interactions that have not previously been described for other biological propulsion systems. The arrangement of vortices during escape swimming produces a similar configuration and impact as that of the well-studied ‘vortex rebound’ phenomenon which occurs when a vortex ring approaches a solid wall. These results extend our understanding of how animals use vortex–vortex interactions and provide important insights that can inform the bioinspired engineering of propulsion systems.

On the Impulse Produced by Chordwise Flexible Pitching Foils in a Quiescent Fluid

2017 ◽  
Vol 140 (4) ◽  
Author(s):  
Francisco J. Huera-Huarte
Keyword(s):  
Particle Image ◽  
Thrust Force ◽  
Particle Image Velocimetry Data ◽  
Reynolds Numbers ◽  
Flexural Stiffness ◽  
Force Measurements ◽  
Vortex Strength ◽  
Image Velocimetry ◽  
Wide Range ◽  
Quiescent Fluid

In this paper, a parametric study showing the impulsive performance of foils with different flexural stiffness pitching in a quiescent fluid is presented. A wide range of Reynolds numbers (different imposed kinematics) and foil rigidities is covered, depicting how flexibility effects on impulse are more important at the largest Reynolds numbers. The impulsive performance of the system is derived from direct thrust force measurements. Passive flexibility alters vortex strength and formation in the wake of the pitching foil. These changes in the wake formation can be used to explain the differences in the measured impulses. The wake dynamics is studied after quantitative analysis of particle image velocimetry data, and it is linked to the momentum transfer generated by the foil.

scholarly journals Experimental Investigation of the Effect of Ice Blockage on Propeller Hydrodynamic Performance

2019 ◽  
Vol 2019 ◽  
pp. 1-19
Author(s):  
Chun-Yu Guo ◽  
Pei Xu ◽  
Chao Wang ◽  
Wei-Peng Xiong
Keyword(s):  
Transverse Direction ◽  
Particle Image ◽  
Fluid Velocity ◽  
Vertical Direction ◽  
Wake Flow ◽  
Hydrodynamic Performance ◽  
Propeller Wake ◽  
Image Velocimetry ◽  
Measurement Results ◽  
Thrust And Torque

This experimental study investigates the influence of different sizes, quantities, and axial positions of model ice on propeller hydrodynamic performance. We used particle image velocimetry measurements to analyze the characteristics of the propeller wake flow field. The measurement results show that ice blockage leads to an increase in propeller thrust, torque, and efficiency. The smaller the advance coefficient of the propeller is, the smaller the influence of model ice on propeller blockage is. As the model ice becomes thicker and the thrust and efficiency of the propeller increase, the propeller torque is smaller for low advance coefficient and higher for high advance coefficient. The wider the model ice is, the larger the thrust and torque of the propeller are. Once the model ice width exceeds the propeller diameter, the change in its width has no effect on propeller efficiency. When the propeller is blocked with model ice, the fluid velocity in the wake flow reduces in the inflow direction, and the increase in fluid velocity in the horizontal transverse direction and variation of fluid velocity in the vertical direction are related to the model ice width.

Comparison Between PIV Results and CFD Simulations of Air Flows in a Thin Electronics Casing Model

2012 ◽  
Author(s):  
Masaru Ishizuka ◽  
Tomoyuki Hatakeyama ◽  
Risako Kibushi ◽  
Yasushi Nishino ◽  
Shinji Nakagawa
Keyword(s):  
Fluid Dynamics ◽  
Particle Image Velocimetry ◽  
Particle Image ◽  
Electronic Equipment ◽  
Cfd Simulations ◽  
Cooling Performance ◽  
Piv Measurement ◽  
Image Velocimetry ◽  
Measurement Results ◽  
Good Agreement

The aim of this study was to acquire benchmark test data for simulating computational fluid dynamics in thin electronic equipment. Flow in the model of thin electronic equipment was measured by using particle image velocimetry PIV). Dummy components were placed in the model and their configurations altered. The temperature rise of a heat source in the model was also measured and the cooling performance examined. The PIV measurement results revealed the changes in flow with changes in the configuration of the components. Comparison of the experimental results with numerical results showed good agreement in terms of the overall velocity field.

scholarly journals THERMOCAPILLARY MONITORING USING PARTICLE IMAGE VELOCIMETRY ASSOCIATED WITH DYNAMIC LASER SPECKLE

2020 ◽  
Vol 5 (1) ◽  
pp. 1-5
Author(s):  
Ellem Waleska Nascimento da Fonseca Contado ◽  
Roberto Alves Braga Júnior ◽  
Henrique Coelho Barbosa ◽  
Renan Oliveira Reis ◽  
Radhakrishna Prabhu
Keyword(s):  
Particle Image Velocimetry ◽  
Laser Beam ◽  
Velocity Distribution ◽  
Particle Image ◽  
Physical Phenomenon ◽  
Flow Analysis ◽  
Ccd Camera ◽  
Laser Speckle ◽  
Piv Technique ◽  
Image Velocimetry

Thermocapillarity is a physical phenomenon used in many industrial processes, mainly in the field of miniaturization. Thermocapillary forces are the base of thermocapillary pumping (TCP), in which a drop of liquid moves through a microchannel or flat surface after temperature gradient occurs. The objective of this work was to study the thermocapillary convection during pumping without inserting external particles, monitored by the Particle Image Velocimetry (PIV) technique. The experiment consisted of a Pasteur tube containing a yellow fluorescein solution (0.02, 0.04, 0.06, 0.08, and 0.1 Molar), illuminated by a laser beam of 545 nm, 40 mW. After 2 minutes of illumination, the thermocapillary movement occurred at a distance of 0.05 mm below the meniscus when using a laser beam of 545 nm, 3 mW. The images were captured by a charge-coupled device (CCD) camera and processed using the PIV technique. The results showed an internal conversion capacity between the intersystem crossing, vibrational, and relaxation phenomena, also demonstrating the potential for applying the proposed approach. The images presented velocity distribution caused by thermocapillarity. The PIV was a useful tool for convective flow analysis if connected to appropriate image processing and enhancement techniques. In conclusion, the research showed the images with velocity distribution caused by thermocapillarity.

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