Turbulent characteristics of a flowfield over a heated riblet surface

Kazumi Tsunoda, Mitsuhiro Kurihara

Research output: Contribution to journalArticle

Abstract

Experimental studies of a turbulent flowfield developing over the heated riblet surface were carried out in a low-speed wind tunnel. The instantaneous velocity fields were measured by using a particle image velocimetry (PIV) in a plane that was parallel to the riblet surface, and compared with those over a heated smooth surface. The reduction ratio of the skin friction coefficient over the heated riblet surface reached up to 8% for the riblet spacing of about 13 viscous wall units. This is almost the same spacing as that obtained for the non-heated condition. The streamwise and wall-normal turbulent intensities against the local time-mean velocity were decreased in their peak values for the heated riblet. The instantaneous fluctuating velocity fields obtained by subtracting the ensemble-averaged velocity from instantaneous velocity vectors revealed that the appearance of a low-speed streaky structure became more intermittent over the riblet surface. This fact suggested a reduction in turbulence production in the near-wall region. Furthermore, it was also found that a perturbation of the spanwise velocity fluctuation was restricted near the riblet surface.

Original languageEnglish
Pages (from-to)818-825
Number of pages8
JournalNihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B
Volume74
Issue number4
Publication statusPublished - 2008 Apr

Fingerprint

riblets
velocity distribution
spacing
low speed wind tunnels
Skin friction
skin friction
Velocity measurement
Wind tunnels
particle image velocimetry
Turbulence
coefficient of friction
low speed
turbulence
perturbation

Keywords

  • Particle image velocimetry
  • Riblet
  • Skin friction coefficient
  • Streaky structure
  • Turbulence
  • Turbulent flow

ASJC Scopus subject areas

  • Mechanical Engineering

Cite this

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title = "Turbulent characteristics of a flowfield over a heated riblet surface",
abstract = "Experimental studies of a turbulent flowfield developing over the heated riblet surface were carried out in a low-speed wind tunnel. The instantaneous velocity fields were measured by using a particle image velocimetry (PIV) in a plane that was parallel to the riblet surface, and compared with those over a heated smooth surface. The reduction ratio of the skin friction coefficient over the heated riblet surface reached up to 8{\%} for the riblet spacing of about 13 viscous wall units. This is almost the same spacing as that obtained for the non-heated condition. The streamwise and wall-normal turbulent intensities against the local time-mean velocity were decreased in their peak values for the heated riblet. The instantaneous fluctuating velocity fields obtained by subtracting the ensemble-averaged velocity from instantaneous velocity vectors revealed that the appearance of a low-speed streaky structure became more intermittent over the riblet surface. This fact suggested a reduction in turbulence production in the near-wall region. Furthermore, it was also found that a perturbation of the spanwise velocity fluctuation was restricted near the riblet surface.",
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AU - Kurihara, Mitsuhiro

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AB - Experimental studies of a turbulent flowfield developing over the heated riblet surface were carried out in a low-speed wind tunnel. The instantaneous velocity fields were measured by using a particle image velocimetry (PIV) in a plane that was parallel to the riblet surface, and compared with those over a heated smooth surface. The reduction ratio of the skin friction coefficient over the heated riblet surface reached up to 8% for the riblet spacing of about 13 viscous wall units. This is almost the same spacing as that obtained for the non-heated condition. The streamwise and wall-normal turbulent intensities against the local time-mean velocity were decreased in their peak values for the heated riblet. The instantaneous fluctuating velocity fields obtained by subtracting the ensemble-averaged velocity from instantaneous velocity vectors revealed that the appearance of a low-speed streaky structure became more intermittent over the riblet surface. This fact suggested a reduction in turbulence production in the near-wall region. Furthermore, it was also found that a perturbation of the spanwise velocity fluctuation was restricted near the riblet surface.

KW - Particle image velocimetry

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KW - Streaky structure

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