Open this publication in new window or tab >>2022 (English)In: Iutam Laminar-Turbulent Transition / [ed] Sherwin, S Schmid, P Wu, X, Springer Nature , 2022, Vol. 38, p. 193-202Conference paper, Published paper (Refereed)
Abstract [en]
An experimental investigation aimed at detecting the critical roughness Reynolds number (Re-kk,Re-tr) both with and without Tollmien-Schlichting (T-S) waves is described in this paper. As a novel technique to examine Re-kk,Re-tr systematically, we employed isolated, cylindrical roughnesses with automatically adjustable height of micro-meter precision. The experiment was performed using hot-wire anemometry in flat-plate boundary layers developing under close to zero-pressure-gradient conditions in a low-turbulence level wind tunnel. The present data for Re-kk,Re-tr without T-S waves confirmed previous results and showed a strong correlation between the roughness aspect ratio and root Re-kk,Re-tr. Controlling the roughness height while keeping the free-stream velocity fixed revealed noteworthy hysteresis for Re-kk,Re-tr. As expected the critical roughness Reynolds number decreased with the presence of T-S waves. The necessary T-S wave amplitude needed for transition became smaller with increasing the roughness height with a sudden drop when approaching the critical roughness height without T-S waves.
Place, publisher, year, edition, pages
Springer Nature, 2022
Series
IUTAM Bookseries, ISSN 1875-3507
National Category
Fluid Mechanics
Identifiers
urn:nbn:se:kth:diva-304762 (URN)10.1007/978-3-030-67902-6_16 (DOI)000709087600016 ()2-s2.0-85112602527 (Scopus ID)
Conference
9th IUTAM Symposium on Laminar-Turbulent Transition, SEP 02-06, 2019, Imperial Coll London, London, ENGLAND
Note
Part of proceedings: ISBN 978-3-030-67902-6, ISBN 978-3-030-67901-9
QC 20211112
2021-11-122021-11-122025-02-09Bibliographically approved