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Experimental study of the rotating-disk boundary-layer flow
KTH, School of Engineering Sciences (SCI), Mechanics.
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Rotating-disk flow has been investigated not only as a simple model of cross flow instability to compare with swept-wing flow but also for industrial flow applications with rotating configurations. However the exact nature of laminar-turbulent transi- tion on the rotating-disk flow is still major problem and further research is required for it to be fully understood, in particular, the laminar-turbulent transition process with absolute instability. In addition the studies of the rotating-disk turbulent boundary- layer flow are inadequate to understand the physics of three-dimensional turbulent boundary-layer flow.

In present thesis, a rotating-rotating disk boundary-layer flow has been inves- tigated experimentally using hot-wire anemometry. A glass disk with a flat surface has been prepared to archieve low disturbance rotating-disk environment. Azimuthal velocity measurements using a hot-wire probe have been taken for various conditions. To get a better insight into the laminar-turbulent transition region, a new way to describe the process is proposed using the probability density function (PDF) map of azimuthal fluctuation velocity.

The effect of the edge of the disk on the laminar-turbulent transition process has been investigated. The disturbance growth of azimuthal fluctuation velocity as a function of Reynolds number has a similar trend irrespective of the various edge conditions.

The behaviour of secondary instability and turbulent breakdown has been in- vestigated. It has been found that the kinked azimuthal velocity associated with secondary instability just before turbulent breakdown became less apparent at a cer- tain wall normal heights. Furthermore the turbulent breakdown of the stationary mode seems not to be triggered by its amplitude, however, depend on the appearance of the travelling secondary instability.

Finally, the turbulent boundary layer on a rotating disk has been investigated. An azimuthal friction velocity has been directly measured from the azimuthal velocity profile in the viscous sub-layer. The turbulent statistics normalized by the inner and outer sclaes are presented. 

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. , viii, 50 p.
Series
Trita-MEK, ISSN 0348-467X ; 2012:12
Keyword [en]
Fluid mechanics, boundary layer, rotating disk, laminar-turbulent transition, convective instability, absolute instability, secondary instability, crossflow instability, hot-wire anemometry.
National Category
Fluid Mechanics and Acoustics
Identifiers
URN: urn:nbn:se:kth:diva-95147ISBN: 978-91-7501-409-8 (print)OAI: oai:DiVA.org:kth-95147DiVA: diva2:526665
Presentation
2012-06-08, Seminar room, Brinellvägen 32, KTH, Stockholm, 10:15 (English)
Opponent
Supervisors
Funder
Swedish Research Council, 2010-3886
Note
QC 20120529Available from: 2012-05-29 Created: 2012-05-14 Last updated: 2012-05-29Bibliographically approved
List of papers
1. A new way to describe the transition characteristics of a rotating-disk boundary-layer flow
Open this publication in new window or tab >>A new way to describe the transition characteristics of a rotating-disk boundary-layer flow
2012 (English)In: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Vol. 24, no 3, 031701- p.Article in journal (Refereed) Published
Abstract [en]

A new method of graphically representing the transition stages of a rotating-disk flow is presented. The probability density function contour map of the fluctuating azimuthal disturbance velocity is used to show the characteristics of the boundary-layer flow over the rotating disk as a function of Reynolds numbers. Compared with the variation of the disturbance amplitude (rms) or spectral distribution, this map more clearly shows the changing flow characteristics through the laminar, transitional, and turbulent regions. This method may also be useful to characterize the different stages in the transition process not only for the rotating-disk flow but also for other flows.

National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-93941 (URN)10.1063/1.3696020 (DOI)000302224600001 ()2-s2.0-84859347277 (Scopus ID)
Funder
Swedish Research CouncilStandUp
Note

QC 20120503

Available from: 2012-05-03 Created: 2012-05-03 Last updated: 2017-12-07Bibliographically approved
2. An Experimental Study of Edge Effects on Rotating-Disk Transition
Open this publication in new window or tab >>An Experimental Study of Edge Effects on Rotating-Disk Transition
2012 (English)Report (Other academic)
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-95756 (URN)
Funder
StandUp
Note

QS 2012

Available from: 2012-05-29 Created: 2012-05-29 Last updated: 2013-04-18Bibliographically approved
3. Secondary Instability and Turbulent Breakdown of the Rotating-Disk Flow
Open this publication in new window or tab >>Secondary Instability and Turbulent Breakdown of the Rotating-Disk Flow
2012 (English)Report (Other academic)
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-95757 (URN)
Note
QS 2012Available from: 2012-05-29 Created: 2012-05-29 Last updated: 2012-05-29Bibliographically approved
4. An Experimental Study of a Rotating-Disk Turbulent Boundary-Layer Flow
Open this publication in new window or tab >>An Experimental Study of a Rotating-Disk Turbulent Boundary-Layer Flow
2012 (English)Report (Other academic)
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-95758 (URN)
Funder
StandUp
Note

QS 2012

Available from: 2012-05-29 Created: 2012-05-29 Last updated: 2013-04-18Bibliographically approved

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