Optical Measurement of the Relative Motion of a Spherical Particle in a Micro-Capillary

2011 ◽  
Author(s):  
Debjyoti Sen ◽  
David S. Nobes ◽  
Subir Bhattacharjee ◽  
Sushanta K. Mitra
Keyword(s):  
Velocity Field ◽  
Velocity Profile ◽  
Spherical Particle ◽  
Relative Motion ◽  
Particle Tracking ◽  
Particle Tracking Velocimetry ◽  
Optical Measurement ◽  
Particle Diameter ◽  
Micro Channel ◽  
Neutrally Buoyant

The motion of a neutrally buoyant spherical micro particle suspended in a liquid inside a ‘U’ shaped micro channel is detected using particle tracking velocimetry. The ratio of the particle diameter to the hydraulic diameter of the channel is found to be 0.1. Poiseuille velocity profile is observed inside the micro channel and the spherical particle is convected with the Poiseuille velocity field. The magnitude of the lag factor is determined experimentally and is compared with the values reported in existing literature. The effect of other forces and interactions on the particle is quantitatively studied. It was found that effects of Brownian, Van der Waals and electrostatic forces do not significantly contribute to the velocity of the particle.

scholarly journals Measurements of the Flow in the Vicinity of an Additively Manufactured Turbine Leading-Edge Using X-Ray Particle Tracking Velocimetry

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Alex Ruiz ◽  
Kamel Fezzaa ◽  
Jayanta Kapat ◽  
Samik Bhattacharya
Keyword(s):  
Velocity Field ◽  
Turbine Blade ◽  
Particle Tracking ◽  
High Speed ◽  
Particle Tracking Velocimetry ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Leading Edge ◽  
Inlet Channel ◽  
X Ray

Abstract X-ray particle tracking velocimetry (PTV) is performed, for the first time, to measure the velocity field inside a leading-edge of a turbine blade made by laser-additive-manufacturing (LAM) process. The traditional showerhead holes were replaced by a porous matrix in the leading-edge. The flow through such a leading-edge piece cannot be faithfully recreated by traditional prototype testing methods due to the surface roughness and imperfections caused by LAM process. Hence, direct measurement is the only option. However, it is difficult to measure flow inside such pieces with traditional velocimetry measurements due to the existence of metallic walls. Moreover, small internal size and high flow speeds call for a measurement technique with high spatial and temporal resolutions. To address these issues, we performed time-resolved X-ray PTV using the Advanced Photon Source (APS) synchrotron facility at the Argonne National Laboratory (ANL). A hydraulic system was constructed to run water, mixed with seeding particles, through the leading-edge piece. A high-speed camera captured the images of the seeding particles, which were later processed to create particle tracks. The time-averaged velocity field showed distinct pairs of vortices located in front of the porous outlet inside the leading-edge piece. The inlet channel showed reversed flow due to partial obstruction by the porous inlet of the test piece. Such knowledge of the flow field inside a leading-edge of a turbine blade will help us to design better cooling paths leading to higher cooling efficiency and increased life-span of a turbine blade.

scholarly journals Flow-structure identification in a radially grooved open wet clutch by means of defocusing particle tracking velocimetry

2021 ◽  
Vol 62 (2) ◽  
Author(s):  
Robin Leister ◽  
Thomas Fuchs ◽  
Philipp Mattern ◽  
Jochen Kriegseis
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Velocity Profile ◽  
Particle Tracking ◽  
Particle Tracking Velocimetry ◽  
Structure Identification ◽  
Strong Impact ◽  
Gap Flow ◽  
Wet Clutch ◽  
Wall Shear

AbstractThe volumetric defocusing particle tracking velocimetry (DPTV) approach is applied to measure the flow in the sub-millimeter gap between the disks of a radially grooved open wet clutch. It is shown that DPTV is capable of determining the in-plane velocities with a spatial resolution of $$12\;\upmu \mathrm{m}$$ 12 μ m along the optical axis, which is sufficient to capture the complex and small flow structures in the miniature clutch grooves. A Couette-like velocity profile is identified at sufficient distance from the grooves. Moreover, the evaluation of the volumetric flow information in the rotor-fixed frame of reference uncovers a vortical structure inside the groove, which resembles a cavity roller. This vortex is found to extend well into the gap, such that the gap flow is displaced towards the smooth stator wall. Hence, the wall shear stress at the stator significantly increases in the groove region by up to $$15\%$$ 15 % as compared to the ideal linear velocity profile. Midway between the grooves, the wall shear stress is around $$4\%$$ 4 % lower than the linear reference. Furthermore, significant amounts of positive radial fluxes are identified inside the groove of the rotor; their counterpart are negative fluxes in the smooth part of the gap. The interaction of the roller in the groove and the resulting manipulation of the velocity profile has a strong impact on the wall shear stress and therefore on the drag torque production. In summary, this DPTV study demonstrates the applicability of such particle imaging approaches to achieve new insights into physical mechanisms of sub-millimeter gap flow scenarios in technical applications. These results help to bring the design- and performance-optimization processes of such devices to a new level. Graphic abstract

Simultaneous 3D temperature and velocity field measurements of micro-flow with laser-induced fluorescence and micro-digital holographic particle tracking velocimetry: Numerical study

2015 ◽  
Vol 13 (7) ◽  
pp. 072801-72805
Author(s):  
Longchao Yao Longchao Yao ◽  
Xuecheng Wu Xuecheng Wu ◽  
Jing Yang Jing Yang ◽  
Yingchun Wu Yingchun Wu ◽  
Xiang Gao Xiang Gao ◽  
...  
Keyword(s):  
Velocity Field ◽  
Particle Tracking ◽  
Particle Tracking Velocimetry ◽  
Numerical Study ◽  
Field Measurements ◽  
Laser Induced Fluorescence ◽  
Micro Flow
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