Measurement of developing turbulent flow in a U-bend of circular cross-section

Gun Hyee Lee, Young Don Choi, Seong Ho Han

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Hot-wire measurements of the full mapping of the velocity and Reynolds stress components are reported for developing turbulent flow in a strongly curved 180 deg pipe and its tangents. A slanted wire is rotated into 6 orientations and the voltage outputs from wires are combined to obtain the mean velocity and Reynolds stress components. The strength of secondary flow reaches up to the 28% of bulk mean velocity. The strong counter-rotating vortex pair induced by the transverse pressure gradient and centrifugal force imbalance grows up to θ=67.5°into the bend. But the vortex pair breaks down into two cell pattern after θ=90° Core vortex formation and reversal of secondary flow direction along the bend symmetry plane is cleanly found in the secondary vector plot. At θ=67.5° and θ=90° into bend a large "trough" develops in the longitudinal velocity toward the inside of the bend due to the breakdown of secondary flow. In the bend, the mean longitudinal velocity component changes little after θ=90°, but secondary flow never achieves fully-developed state. Similar behaviors are observed in the radial and circumferential stresses.

Original languageEnglish
Pages (from-to)348-359
Number of pages12
JournalJournal of Mechanical Science and Technology
Volume21
Issue number2
DOIs
Publication statusPublished - 2007 Feb 1

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Turbulent flow
Secondary flow
Vortex flow
Wire
Pressure gradient
Pipe
Electric potential

Keywords

  • Air jet loom
  • Backward facing step
  • Recirculating flow
  • Transonic/supersonic flows
  • Unsteady flow

ASJC Scopus subject areas

  • Mechanical Engineering

Cite this

Measurement of developing turbulent flow in a U-bend of circular cross-section. / Lee, Gun Hyee; Choi, Young Don; Han, Seong Ho.

In: Journal of Mechanical Science and Technology, Vol. 21, No. 2, 01.02.2007, p. 348-359.

Research output: Contribution to journalArticle

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N2 - Hot-wire measurements of the full mapping of the velocity and Reynolds stress components are reported for developing turbulent flow in a strongly curved 180 deg pipe and its tangents. A slanted wire is rotated into 6 orientations and the voltage outputs from wires are combined to obtain the mean velocity and Reynolds stress components. The strength of secondary flow reaches up to the 28% of bulk mean velocity. The strong counter-rotating vortex pair induced by the transverse pressure gradient and centrifugal force imbalance grows up to θ=67.5°into the bend. But the vortex pair breaks down into two cell pattern after θ=90° Core vortex formation and reversal of secondary flow direction along the bend symmetry plane is cleanly found in the secondary vector plot. At θ=67.5° and θ=90° into bend a large "trough" develops in the longitudinal velocity toward the inside of the bend due to the breakdown of secondary flow. In the bend, the mean longitudinal velocity component changes little after θ=90°, but secondary flow never achieves fully-developed state. Similar behaviors are observed in the radial and circumferential stresses.

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