| dc.contributor |
Hassan , Yassin A . |
|
| dc.creator |
Dominguez Ontiveros , Elvis Efren |
|
| dc.date |
2005 -11 -01T15 :46 :29Z |
|
| dc.date |
2005 -11 -01T15 :46 :29Z |
|
| dc.date |
2004 -08 |
|
| dc.date |
2005 -11 -01T15 :46 :29Z |
|
| dc.date.accessioned |
2013 -03 -12T17 :41 :06Z |
|
| dc.date.available |
2013 -03 -12T17 :41 :06Z |
|
| dc.date.issued |
2013 -03 -12 |
|
| dc.identifier |
http : / /hdl .handle .net /1969 .1 /2582 |
|
| dc.identifier.uri |
http : / /hdl .handle .net /1969 .1 /2582 |
|
| dc.description |
The effects of microbubbles injection in the boundary layer of a turbulent channel flow are investigated . Electrolysis demonstrated to be an effective method to produce microbubbles with an average diameter of 30 ? ?m and allowed the placement of microbubbles at desired locations within the boundary layer .
Measurement of velocity fluctuations and the instantaneous wall shear stress were carried out in a channel flow facility .
The wall shear stress is an important parameter that can help with the characterization of the boundary layer . This parameter can be obtained indirectly by the measurement of the flow pressure at the wall .
The wall shear stress in the channel was measured by means of three different independent methods : measurement of the pressure gradient by a differential pressure transducer , Particle Image Velocimetry (PIV ) , and an optical wall shear stress sensor . The three methods showed reasonable agreement of the wall shear stress values for single -phase flow . However , differences as skin friction reductions were observed when the microbubbles were injected . Several measurements of wall -pressure were taken at various Reynolds numbers that ranged from 300 up to 6154 . No significant drag reduction was observed for flows in the laminar range ; however , a drag reduction of about 16 % was detected for turbulent Reynolds numbers .
The wall -pressure measurements were shown to be a powerful tool for the measurement of drag reduction , which could help with the design of systems capable of controlling the skin friction based on feedback given by the wall -pressure signal .
The proposed measurement system designed in this work has capabilities for application in such diverse fields as multiphase flows , drag reduction , stratified flows , heat transfer among others . The synchronization between independent systems and apparatus has the potential to bring insight about the complicated phenomena involved in the nature of fluid flows . |
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| dc.format |
6644628 bytes |
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| dc.format |
electronic |
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| dc.format |
application /pdf |
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| dc.format |
born digital |
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| dc.language |
en _US |
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| dc.publisher |
Texas A &M University |
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| dc.subject |
drag reduction |
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| dc.subject |
shear stress |
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| dc.subject |
microbubble |
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| dc.subject |
pressure transducer |
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| dc.subject |
optical shear stress sensor |
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| dc.subject |
PIV |
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| dc.title |
Wall -pressure and PIV analysis for microbubble drag reduction investigation |
|
| dc.type |
Book |
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| dc.type |
Thesis |
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| dc.type |
Electronic Thesis |
|
| dc.type |
text |
|