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Effects of spatial resolution on PIV investigation of a turbulent orifice jet
Sapienza University of Rome.ORCID iD: 0000-0002-8038-1127
Sapienza University of Rome.ORCID iD: 0000-0002-5125-3337
2012 (English)In: 16th International Symposium on Applications of Laser Techniques to Fluid Mechanics, Lisbon, 2012Conference paper, Published paper (Refereed)
Abstract [en]

Some of the most interesting turbulent phenomena are jets, the study of which is useful to reach a deep knowledge of mixing in fluids. Among all jets, there exists one, the orifice jet, which is still not fully understood because of its intrinsic complexity, e.g. the "vena contracta" phenomenon, though its wide range of applications ranging over underwater propulsion, pollution dispersion and studies on the cardiocirculatory system. In this work, the attention is focused to the large-scale statistics (mean field and higher statistical moments of the velocity) and to the small-scale statistics (velocity derivative statistical moments), with a special care regarding the effect of spatial resolution on Particle Image Velocimetry (PIV) measurements. To investigate the effect of spatial resolution on the measurements, framed areas of different size have been considered by changing the magnification factor (namely the object plane distance). Making reference to the orifice diameter D, squared regions 2D x 2D, 3D x 3D, 4D x 4D and 5D x 5D have been framed on the acquisition camera. Regarding to the large scales, first of all the occurrence of the vena contracta phenomenon for an orifice jet has been shown in several ways. In addition, it has been highlighted the small influence of spatial resolution on low order statistical moments, which slightly rises, due to local averaging, as the order of the statistics becomes higher. Then small scale features of the jet have been examined, particularly with interest to the evaluation of spatial derivatives of velocity components and then to the fulfillment of isotropy hypotheses of the jet. Based on those data, an incomplete local isotropy condition is attained, although restricted to the near zone, and an influence of spatial resolution high on the determination of local features of such a jet and moderate on the overall behavior of spatial derivatives and to the deductions about symmetry hypotheses.

Place, publisher, year, edition, pages
2012.
National Category
Aerospace Engineering
Identifiers
URN: urn:nbn:se:kth:diva-223697OAI: oai:DiVA.org:kth-223697DiVA, id: diva2:1186526
Conference
16th International Symposium on Applications of Laser Techniques to Fluid Mechanics
Note

QC 20180312

Available from: 2018-02-28 Created: 2018-02-28 Last updated: 2018-03-12Bibliographically approved

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Lacagnina, GiovanniRomano, Giovanni Paolo
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  • apa
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