Control of turbulent separated flow in a plane diffuser using periodic perturbation (control effects and response of velocity field)

Nobumasa Ishibashi, Kenta Aoki, Shinnosuke Obi, Shigeaki Masuda

Research output: Contribution to journalArticle

Abstract

The effects of periodic perturbation on turbulent separated flow in a two-dimensional asymmetric diffuser were investigated. Measurements of velocity fields were undertaken using a LDV, and data reduction was conducted on a time-averaged as well as ensemble-averaged manner that made the mean-periodic-turbulent decomposition possible. Effects of imposed perturbation on the velocity field strongly depend on the frequency of the perturbation, and the optimum frequency ranges between 0.01≤St≤0.04, with St being the perturbation frequency normalized by the channel height at the diffuser inlet and the maximum inlet velocity. At the optimum frequency, the effect of perturbation appears as an organized velocity fluctuation along a separated shear flow, resulting in the enhancement of momentum transport, which is the primary effect of imposed perturbation. An increase in the turbulent Reynolds stress component in the recirculation region is also observed, indicating the secondary effect of the organized fluid motion due to periodic perturbation.

Original languageEnglish
Pages (from-to)62-68
Number of pages7
JournalNippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B
Volume63
Issue number605
Publication statusPublished - 1997 Jan
Externally publishedYes

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separated flow
diffusers
Turbulent flow
velocity distribution
perturbation
Shear flow
Data reduction
Momentum
Decomposition
Reynolds stress
data reduction
Fluids
shear flow
frequency ranges
momentum
decomposition
augmentation
fluids

ASJC Scopus subject areas

  • Mechanical Engineering

Cite this

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AU - Aoki, Kenta

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AU - Masuda, Shigeaki

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