Particle image velocimetry studies on the swirling flow structure in the vortex gripper

2012 ◽  
Vol 227 (9) ◽  
pp. 1927-1937 ◽  
Author(s):  
Qiong Wu ◽  
Qian Ye ◽  
GuoXiang Meng
Keyword(s):  
Reynolds Number ◽  
Particle Image Velocimetry ◽  
Turbulent Flow ◽  
Flow Structure ◽  
Particle Image ◽  
Swirling Flow ◽  
Tangential Velocity ◽  
Internal Flow ◽  
Dynamics Simulation ◽  
Image Velocimetry

In this article, particle image velocimetry was used to measure the two-dimensional flow field for vortex gripper. The vortex gripper was divided into two parts for respective research, including vortex cup and the gas film gap. In the part of vortex cup, the tangential velocity increases gradually, and the velocity decreases intensely in the vicinity of the vortex cup’s wall after it reaches maximum. In addition, the velocity decreases gradually with the increase of the gas film gap. In the part of gas film gap, the tangential velocity increases to maximum along the radial direction first; after the air flows into the gas film gap due to the viscous impedance, it decreases gradually. When the gas film gap’s thickness is smaller, the velocity almost decreases to zero at the external edge of the skirt. However, when the gas film gap increases to a certain thickness, the velocity does not decrease to zero, and the flow air still keeps a certain speed out of it. The velocity decreases gradually with the increase of the gas film gap. The radial velocity in the vortex cup and the gas film gap is of very small order of magnitude comparing with the average velocity and tangential velocity. The analysis of the Reynolds number shows that the flow in the vortex cup is the turbulent flow, and at the part of the gas film gap, the Reynolds number increases with the increase of the gas film gap, and the flow changes from the laminar flow to the turbulent flow. Through the particle image velocimetry experiment, the vortex gripper’s internal flow structure is studied. It is the theory support of the computational fluid dynamics simulation study for vortex gripper and the structure optimization in the future work.

Experimental Study of the Flow Structure in Fire-Induced Whirlwinds Downwind of a Fire Using Particle Image Velocimetry

2007 ◽  
Author(s):  
Masahiko Shinohara ◽  
Sanae Matsushima
Keyword(s):  
Experimental Study ◽  
Particle Image Velocimetry ◽  
Flow Visualization ◽  
Flow Structure ◽  
Particle Image ◽  
Reverse Flow ◽  
Tangential Velocity ◽  
Visualization Technique ◽  
Image Velocimetry ◽  
In Fire

The flow structure of fire-induced whirlwinds that occur downwind of a 90-cm-diameter methanol flame was investigated using particle image velocimetry (PIV) and a flow visualization technique. The PIV images showed that the whirlwinds occurred as counter-rotating vortices on both sides of a reverse flow downwind of the flame that moved toward it near the floor. The whirlwinds started near the floor and extended upwards, with a lower tangential velocity near the floor. The radius of the forced vortex region in the whirlwinds increased above a height of 11 cm. Whirlwinds downwind of the 90-cm-diameter methanol flame behaved the same as whirlwinds downwind of a 3-cm-diameter flame that were investigated in a previous study.

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 Experiment and Computational Fluid Dynamics Simulation of Flow Around Rigid Cylinder

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Guangyao Wang ◽  
Ye Tian ◽  
Spyros A. Kinnas
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Particle Image Velocimetry ◽  
Vector Fields ◽  
Particle Image ◽  
Cfd Simulation ◽  
Dynamics Simulation ◽  
Reynolds Stresses ◽  
Rigid Cylinder ◽  
Image Velocimetry

This work focuses on the study of the flow around a rigid cylinder with both particle image velocimetry (PIV) experiment and computational fluid dynamics (CFD) simulation. PIV measurements of the flow field downstream of the cylinder are first presented. The boundary conditions for CFD simulations are measured in the PIV experiment. Then the PIV flow is compared with both Reynolds-averaged Navier–Stokes (RANS) two-dimensional (2D) and large eddy simulation (LES) three-dimensional (3D) simulations performed with ANSYS fluent. The velocity vector fields and time histories of velocity are analyzed. In addition, the time-averaged velocity profiles and Reynolds stresses are analyzed. It is found that, in general, LES (3D) gives a better prediction of flow characteristics than RANS (2D).

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