Experimental Study of Flow Structure in Converging–Diverging Axisymmetric Geometry

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Eirik Volent ◽  
Kristian Sagmo ◽  
Bjørn Winther Solemslie ◽  
Ole Gunnar Dahlhaug
Keyword(s):  
Experimental Study ◽  
Flow Structure ◽  
Particle Image ◽  
Fluid Velocity ◽  
Solid Particles ◽  
Fluid Stream ◽  
Vena Contracta ◽  
Image Velocimetry ◽  
High Fluid ◽  
Stream Erosion

Abstract Control valves, nozzles, and other mechanical flow constricting constructions often introduce highly turbulent flow downstream of vena contracta. When solid particles are present in the fluid stream erosion can occur due to the high fluid velocity and turbulence, both in the converging and diverging section of a constriction. This paper presents an experimental study of such flow structure in a converging–diverging valve geometry. The purpose of the study is to obtain velocity profiles downstream of vena contracta by the use of particle image velocimetry measurements. Profiles and flow structure, with and without introduced swirl component, is investigated and discussed with respect to erosion in such specific geometries.

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.

Experimental study on the wake fields of a Panamax Bulker based on stereo particle image velocimetry

2018 ◽  
Vol 165 ◽  
pp. 91-106 ◽  
Author(s):  
Chun-yu Guo ◽  
Tie-cheng Wu ◽  
Wan-zhen Luo ◽  
Xin Chang ◽  
Jie Gong ◽  
...  
Keyword(s):  
Experimental Study ◽  
Particle Image Velocimetry ◽  
Particle Image ◽  
Image Velocimetry ◽  
Stereo Particle Image Velocimetry ◽  
Wake Fields

Computational Fluid Dynamics and Particle Image Velocimetry Supported Examination of Bidirectional Velocity Probes for Measurements in Flames

2013 ◽  
Vol 6 (1) ◽  
Author(s):  
Nadir Yilmaz ◽  
Brian C. Hogan ◽  
Humberto Bocanegra ◽  
A. Burl Donaldson ◽  
Walt Gill
Keyword(s):  
Fluid Dynamics ◽  
Experimental Study ◽  
Reynolds Number ◽  
Wind Tunnel ◽  
Pressure Difference ◽  
Particle Image ◽  
Amplification Factor ◽  
Local Velocity ◽  
Bernoulli’S Equation ◽  
Image Velocimetry

The bidirectional velocity probe has been used in various flames to measure local velocity. The device is based on the pressure difference between a closed forward facing cavity and a closed rearward facing cavity. The probes have been noted to indicate a pressure difference greater than that which would be predicted based on Bernoulli's equation. Each device must be experimentally calibrated in a wind tunnel at similar Reynolds number to determine its “amplification factor.” This study uses PIV, flow visualization and CFD to examine the flow field around the probe, as well as an experimental study which compares various probe configurations for measurement of velocity by pressure differential. The conclusion is that the amplification factor is indeed greater than unity but use of the wind tunnel for calibration is questionable.

Flow Field Analysis of Dielectrophoretically-Suspended Particles

2007 ◽  
Author(s):  
Stuart J. Williams ◽  
Steven T. Wereley
Keyword(s):  
Electric Fields ◽  
Particle Image ◽  
Fluid Velocity ◽  
Microfluidic Channel ◽  
Velocity Fields ◽  
Field Analysis ◽  
Tracer Particles ◽  
Image Velocimetry ◽  
Flow Field Analysis ◽  
Complete Investigation

Understanding the fluid dynamics around a particle in suspension is important for a complete investigation of many hydrodynamic phenomena, including microfluidic models. A novel tool that has been used to analyze fluid velocity fields in microfluidics is micro-resolution particle image velocimetry (μPIV) [1]. Dielectrophoresis (DEP) is a technique that can translate and trap particles by induced polarization in the presence of nonuniform electric fields. In this paper, DEP has been used to capture and suspend a single 10.1μm diameter spherical particle in a microfluidic channel. μPIV is then used with smaller tracer particles (0.5μm) to investigate the hydrodynamics of fluid flow past the trapped particle.

A New Methodology for Generation of Solitary Water Waves in Laboratory

2020 ◽  
Author(s):  
Xiao Liu ◽  
Yong Liu
Keyword(s):  
Solitary Wave ◽  
Wave Height ◽  
Water Waves ◽  
Particle Image ◽  
Fluid Velocity ◽  
Simple System ◽  
Wave Surface ◽  
Wave Flume ◽  
Image Velocimetry ◽  
Laboratory Flume

Abstract In this article, a very simple system based on the enhanced dam-break flows was proposed and implemented to generate solitary wave with larger relative wave height (the ratio of wave height to water depth) in a laboratory flume. The experimental results showed that stable waves with the solitary wave profiles were successfully generated in the wave flume. The wave surface elevations were recorded by a series of wave gauges, and the fluid velocity field of the solitary wave was measured by Particle Image Velocimetry (PIV) system. The measurements of solitary wave profile, celerity and horizontal fluid velocity were also compared with the predictions by three different solitary wave theories. Results demonstrated that the present simple system was reliable and effective for the generation of solitary waves in laboratory.

scholarly journals Experimental Study of Heat Convection From Stationary and Oscillating Circular Cylinder in Cross Flow

2000 ◽  
Vol 123 (1) ◽  
pp. 51-62 ◽  
Author(s):  
H. G. Park ◽  
Morteza Gharib
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Particle Image ◽  
Forced Oscillation ◽  
Oscillation Amplitude ◽  
Cross Flow ◽  
Digital Particle Image Velocimetry ◽  
Image Velocimetry ◽  
Vortex Shedding Frequency ◽  
Shedding Frequency

An experimental study is made on the processes of heat transfer from the surface of a forced oscillating cylinder in a crossflow. A range of oscillation amplitude A/D=0.1,0.2, forced oscillation frequency 0<Stc<1, and Reynolds number (Re=550, 1100, 3500) is covered in water Pr=6. Besides the increase at the natural vortex shedding frequency, large increases in the heat transfer are found at certain superharmonics. By using Digital Particle Image Velocimetry/Thermometry (DPIV/T), the increase in the heat transfer rate is found to correlate inversely with the distance at which vortices roll-up behind the cylinder, i.e., the distance decreases when the heat transfer increases. The cause of the increase is found to be the removal of the stagnant and low heat convecting fluid at the base of the cylinder during the roll-up of the vortices.

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