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ID 119362
Author
Matsudaira, Hayato The University of Tokushima
Fujimura, Hayato The University of Tokushima
Ohno, Hideki The University of Tokushima
Keywords
Pipe Flow
Transition
Boundary Layer
Turbulence
Inlet Region
Isolated Turbulent Patch
Propagation Velocity
Turbulent Spot
Content Type
Journal Article
Description
The laminar-turbulent transition of a boundary layer induced by a jet injection in the inlet region of a circular pipe was experimentally investigated. The jet was periodically injected radially from a small hole in the inlet region into the pipe flow. Axial velocity was measured by a hot-wire anemometer. The turbulence induced by the jet within the boundary layer developed into turbulent patches which then grew in the axial, circumferential and radial directions downstream. The shape of the patches shown by the intermittency factor in the diametrical plane was similar to the turbulent spot in the flat plate boundary layer at first, then became similar to the turbulent slug in the pipe flow developed downstream. The turbulent patches protruded from the boundary layer after they grew and reached the circumferential opposite side, although they stayed within the boundary layer as long as the shape was turbulent spot-like in the diametrical plane. The propagation velocity at the leading edge became faster than the cross-sectional velocity, though it turned slower at the trailing edge. Therefore, the growth rate of its axial length varied downstream. The growth rate of the patches' circumferential length was smaller than that in the turbulent spot under zero pressure gradient and was almost the same as the spot under favorable pressure gradient.
Journal Title
Journal of Fluid Science and Technology
ISSN
18805558
Publisher
日本機械学会
Volume
8
Issue
3
Start Page
436
End Page
451
Published Date
2013
EDB ID
DOI (Published Version)
URL ( Publisher's Version )
FullText File
language
eng
TextVersion
Author
departments
Science and Technology