Experimental investigation of sound generation by a protuberance in a laminar boundary layer

Journal Article · Fri Aug 15 04:00:00 EDT 2014 · Physics of Fluids (1994)

DOI:https://doi.org/10.1063/1.4894011· OSTI ID:22311053

Kobayashi, M.; Asai, M.; Inasawa, A. ^[1]

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1. Department of Aerospace Engineering, Tokyo Metropolitan University, 6-6 Asahigaoka, Hino, Tokyo 191-0065 (Japan)

Sound radiation from a two-dimensional protuberance glued on the wall in a laminar boundary layer was investigated experimentally at low Mach numbers. When the protuberance was as high as the boundary-layer thickness, a feedback-loop mechanism set in between protuberance-generated sound and Tollmien-Schlichting (T-S) waves generated by the leading-edge receptivity to the upstream-propagating sound. Although occurrence of a separation bubble immediately upstream of the protuberance played important roles in the evolution of instability waves into vortices interacting with the protuberance, the frequency of tonal vortex sound was determined by the selective amplification of T-S waves in the linear instability stage upstream of the separation bubble and was not affected by the instability of the separation bubble.

• OSTI ID: 22311053
• Journal Information: Physics of Fluids (1994), Journal Name: Physics of Fluids (1994) Journal Issue: 8 Vol. 26; ISSN 1070-6631; ISSN PHFLE6
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AMPLIFICATION
BOUNDARY LAYERS
BUBBLES
FEEDBACK
INSTABILITY
S WAVES
SOUND WAVES
THICKNESS
TWO-DIMENSIONAL CALCULATIONS
VORTICES
WALLS