Experimental Study of Jet Flow Impingement Within a Rod Bundle Using PIV Technique

2008 ◽  
Author(s):  
Noushin Amini ◽  
Yassin A. Hassan
Keyword(s):  
Particle Image ◽  
Rectangular Channel ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Reynolds Stresses ◽  
Particle Image Velocimetry Technique ◽  
Time Resolved ◽  
Rod Bundle ◽  
Piv Technique ◽  
Image Velocimetry

In this investigation Particle Image Velocimetry technique was implemented to a matched refractive index facility which was placed in a rectangular channel of L:1016 mm×W:76.2 mm×H:76.2 mm. Water was pumped into either one or both of the inlet jets which were entering the channel’s top wall with several different Reynolds numbers. The instantaneous and time-resolved velocity fields were successfully obtained from which several flow characteristics such as vorticity, turbulence instabilities and Reynolds stresses can be calculated.

A particle image velocimetry study on the pulsatile flow characteristics in straight tubes with an asymmetric bulge

2000 ◽  
Vol 214 (5) ◽  
pp. 655-671 ◽  
Author(s):  
S C M Yu ◽  
J B Zhao
Keyword(s):  
Particle Image Velocimetry ◽  
Steady Flow ◽  
Pulsatile Flow ◽  
Flow Condition ◽  
Particle Image ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Working Fluid ◽  
Flow Conditions ◽  
Image Velocimetry

Flow characteristics in straight tubes with an asymmetric bulge have been investigated using particle image velocimetry (PIV) over a range of Reynolds numbers from 600 to 1200 and at a Womersley number of 22. A mixture of glycerine and water (approximately 40:60 by volume) was used as the working fluid. The study was carried out because of their relevance in some aspects of physiological flows, such as arterial flow through a sidewall aneurysm. Results for both steady and pulsatile flow conditions were obtained. It was found that at a steady flow condition, a weak recirculating vortex formed inside the bulge. The recirculation became stronger at higher Reynolds numbers but weaker at larger bulge sizes. The centre of the vortex was located close to the distal neck. At pulsatile flow conditions, the vortex appeared and disappeared at different phases of the cycle, and the sequence was only punctuated by strong forward flow behaviour (near the peak flow condition). In particular, strong flow interactions between the parent tube and the bulge were observed during the deceleration phase. Stents and springs were used to dampen the flow movement inside the bulge. It was found that the recirculation vortex could be eliminated completely in steady flow conditions using both devices. However, under pulsatile flow conditions, flow velocities inside the bulge could not be suppressed completely by both devices, but could be reduced by more than 80 per cent.

Entrainment and topology of accelerating shear layers

2016 ◽  
Vol 811 ◽  
pp. 37-50 ◽  
Author(s):  
Giuseppe A. Rosi ◽  
David E. Rival
Keyword(s):  
Shear Layer ◽  
Particle Image ◽  
Point Vortex ◽  
Reynolds Numbers ◽  
Shear Layers ◽  
Circular Path ◽  
Entrainment Rate ◽  
Time Resolved ◽  
And Topology ◽  
Image Velocimetry

A constantly accelerating circular plate was investigated towards understanding the effect of non-stationarity on shear-layer entrainment and topology. Dye visualizations and time-resolved particle image velocimetry measurements were collected for normalized accelerations spanning three orders of magnitude. Increasing acceleration acts to organize shear-layer topology. Specifically, the Kelvin–Helmholtz instabilities within the shear layer better adhered to a circular path and exhibited consistent and repeatable spacing. Normalized starting-vortex circulation was observed to collapse with increasing acceleration, which one might not expect due to increased levels of mixing at higher instantaneous Reynolds numbers. The entrainment rate was shown to increase nonlinearly with increasing acceleration. This was attributed to closer spacing between instabilities, which better facilitates the roll-up of fluid between the shear layer and vortex core. The shear-layer organization observed at higher accelerations was associated with smaller spacings between instabilities. Specifically, analogous point-vortex simulations demonstrated that decreasing the spacing between instabilities acts to localize and dampen perturbations within an accelerating shear layer.

PIV Investigation of an Open Channel Flow Over a Forward Facing Step

2007 ◽  
Author(s):  
M. K. Shah ◽  
M. F. Tachie
Keyword(s):  
Open Channel ◽  
Particle Image ◽  
Open Channel Flow ◽  
Reynolds Stresses ◽  
Velocity Measurements ◽  
Particle Image Velocimetry Technique ◽  
Mean Velocity ◽  
Freestream Velocity ◽  
Image Velocimetry ◽  
Forward Facing Step

The characteristics of an open channel turbulent flow over a forward facing step (FFS) are investigated in the present study. Two step heights, h = 6 and 9 mm, at Reynolds number, Reh, (based on the approach freestream velocity, U0, and step height, h) of 1900 and 2800 respectively were studied. Particle image velocimetry technique (PIV) was used to obtain detailed velocity measurements upstream of the FFS, in the reattachment region (x/h = 0, 1, 2) and in the redevelopment region (x/h = 4, 10, 15 and 50). The boundary layer integral parameters, mean velocity profiles and Reynolds stresses obtained in the reattachment and redevelopment region are used to document some of the salient features of the flow.

Effect of inlet port on the flow in the cylinder of an internal combustion engine

2006 ◽  
Vol 220 (1) ◽  
pp. 73-82 ◽  
Author(s):  
A Yasar ◽  
B Sahin ◽  
H Akilli ◽  
K Aydin
Keyword(s):  
Particle Image Velocimetry ◽  
Velocity Distribution ◽  
Particle Image ◽  
Combustion Engine ◽  
Flow Characteristics ◽  
Intake Port ◽  
Intake Valve ◽  
Piv Technique ◽  
Image Velocimetry ◽  
Image Density

In this study, the characteristics of flow emerging from the inlet of the intake port in the cylinder were investigated experimentally. A particle image velocimetry (PIV) technique was used to measure the velocity distribution in order to observe and analyse the flow behaviour. High-image-density PIV provided acquisition of patterns of instantaneous and averaged vorticity and velocity, revealing the detail of the flow characteristics in the cylinder cavity. With this measuring technique, it is possible to study the effect of intake valve geometry on the flow behaviours. The results showed that the flow structure changed substantially along the cylinder stroke due to the geometry of the intake valve port.

The flow around a pipeline with a spoiler

2009 ◽  
Vol 224 (1) ◽  
pp. 109-121 ◽  
Author(s):  
A A Oner
Keyword(s):  
Shear Stress ◽  
Velocity Vector ◽  
Particle Image ◽  
Reynolds Numbers ◽  
Two Dimensional ◽  
Velocity Vector Field ◽  
Smooth Wall ◽  
Particle Image Velocimetry Technique ◽  
Offshore Pipelines ◽  
Image Velocimetry

Offshore pipelines are buried in the seabed to be protected from the damage caused by hydrodynamic forces or by human activities. However, because of soil erosion and interaction of currents with the pipeline on the moveable seabed, the processes of local scouring and, sometimes, self-burial of pipelines take place. To increase the rate and extent of scouring, the technique of attaching a spoiler to the pipeline has been developed. In this study, two-dimensional, steady, turbulent flow around a horizontal pipeline with a spoiler near a smooth wall is investigated experimentally by using the particle image velocimetry technique. The effect of the spoiler was examined for the Reynolds numbers of ReD=840, 1500, 4150, and 9500 based on the pipe diameter. The effect of the spoiler on the process of scouring is investigated through the parameters of the measured instantaneous and time-averaged patterns of the velocity vector field and the streamline topology. The results indicated that the attachment of the spoiler to the pipeline increases the length of the upstream and downstream separation regions and it is also observed that the spoiler does not significantly increase the rate of the flow that passes through the gap and the shear stress acting on the seabed.

PIV Study on the Dimple Mid-Plane of a Narrow Rectangular Channel With Dimples Applied to One Wall

2011 ◽  
Author(s):  
Lucky V. Tran ◽  
Michelle I. Valentino ◽  
Abhishek Saha ◽  
Carson D. Slabaugh ◽  
Mark Ricklick ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Particle Image ◽  
Rectangular Channel ◽  
Reynolds Numbers ◽  
Secondary Flows ◽  
Local Flow ◽  
Flow Disturbances ◽  
Image Velocimetry ◽  
Channel Aspect Ratio ◽  
Effective Channel

This paper presents an investigation of the fluid flow in the fully developed portion of a rectangular channel (Aspect Ratio of 2) with dimples applied to one wall at channel Reynolds numbers of 20,000, 30,000, and 40,000. The dimples are applied in a staggered-row, racetrack configuration. Results for three different dimple geometries are presented: a large dimple, small dimple, and double dimple. Heat transfer and aerodynamic results from preceding works are presented in Nusselt number and friction factor augmentation plots as determined experimentally. Using particle image velocimetry, the region near the dimple feature is studied in detail in the location of the entrainment and ejection of vortical packets into and out of the dimple; the downstream wake region behind each dimple is also studied to examine the effects of the local flow phenomenon that result in improved heat transfer in the areas of the channel wall not occupied by a feature. The focus of the paper is to examine the secondary flows in these dimpled channels in order to support the previously presented heat transfer trends. The flow visualization is also intended to improve the understanding of the flow disturbances in a dimpled channel; a better understanding of these effects would lead the development of more effective channel cooling designs.

An Experimental Investigation of Turbulent Water Flow in Concentric Annulus Using Particle Image Velocimetry Technique

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
F. E. Rodriguez-Corredor ◽  
Majid Bizhani ◽  
Mohammad Ashrafuzzaman ◽  
Ergun Kuru
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Maximum Velocity ◽  
Viscous Sublayer ◽  
Reynolds Stresses ◽  
Flow Loop ◽  
Particle Image Velocimetry Technique ◽  
Mean Velocity ◽  
Number Range ◽  
Image Velocimetry

Fully developed turbulent flow of water through a horizontal flow loop with concentric annular geometry was investigated using high resolution particle image velocimetry (PIV). Reynolds number range varied from 17,700 to 66,900. Axial mean velocity profile was found to be following the universal wall law (u+ = y+) in the viscous sublayer (y+ < 10) and log law away from the wall (y+> 30). Radial position of zero shear stress and maximum velocity were found to be slightly different (2%). Root mean square values of velocity fluctuations velocity, Reynolds stresses, vorticity, and turbulent kinetic energy budget were also analyzed.

Downstream particle image velocimetry measurements of a circular cylinder—plate junction

2009 ◽  
Vol 223 (8) ◽  
pp. 1837-1849 ◽  
Author(s):  
N A Ozturk ◽  
A Akcayoglu ◽  
B Sahin
Keyword(s):  
Particle Image Velocimetry ◽  
Circular Cylinder ◽  
Particle Image ◽  
Flow Characteristics ◽  
Horseshoe Vortex ◽  
Shear Layers ◽  
Wake Flow ◽  
Piv Technique ◽  
Image Velocimetry ◽  
Series Of Experiments

In the present investigation, special attention was given to the flow characteristics downstream of a circular cylinder mounted on a flat surface for Reynolds numbers of 4000 and 7000. A series of experiments were performed in successive end-view planes with the range of 0≤ XL/ d≤5 using the particle image velocimetry (PIV) technique in order to demonstrate characteristics of wake flow structure and interactions between the shear layers caused by shedding vortices and tails of the horseshoe vortex system emanating from the upstream base of the cylinder. The development and growth of primary vortices in the end-view planes caused by the interactions of core flow and wake flow regions along the inner face of the shedding shear layers were examined quantitatively. Finally, it was concluded that the PIV technique was also capable of providing accurate velocity readings in the end-view planes of the wake flow regions.

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