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On the Effect of Rotational Forces on Rotor Blade Boundary-Layer Transition

Weiss, Armin and Gardner, Anthony and Schwermer, Till and Klein, Christian and Raffel, Markus (2018) On the Effect of Rotational Forces on Rotor Blade Boundary-Layer Transition. In: 2018 AIAA Aerospace Sciences Meeting, pp. 1-17. AIAA SciTech Forum 2018, 07.-11. Jan. 2018, Kissimee, Florida USA. DOI: 10.2514/6.2018-0309

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Official URL: https://arc.aiaa.org/doi/10.2514/6.2018-0309

Abstract

Laminar-turbulent boundary-layer transition is investigated on the suction side of Mach-scaled helicopter rotor blades in climb and analyzed in view of the effect of rotational forces. Spatially highly resolved data and precisely detected transition positions are obtained by means of temperature-sensitive paint and accompanied by local surface pressure measurements at two radial blade sections. The effect of rotational forces is investigated by systematic variation of Rossby number from Ro = 4.76 to 6.95 at Re = 3.7x10^5 and M = 0.22. The findings do not show a measurable effect of rotational forces on boundary-layer transition in the investigated parameter range and suggest predominantly two-dimensional (2D) flow behaviour, which is confirmed by subsequent validation with 2D numerical tools. Based on quantitative agreement between measured and calculated surface pressures, it is shown that experimentally detected transition positions are predicted to within +-4 % chord if a critical amplification factor of N_cr,MSES = 5.6 is used in MSES for transition prediction in the rotor test facility of the DLR Göttingen. The measured transition onset positions are also correlated with the obtained integral growth rates from 2D compressible local linear stability theory to get transition N-factors of N_cr = 8.4 + 0.5 . Correlations are shown to be independent of relative chord Reynolds number and incompressible shape factor at the detected transition onset underlining the capability of 2D numerical techniques based on linear stability theory to model boundary-layer transition in the investigated parameter range.

Item URL in elib:https://elib.dlr.de/119037/
Document Type:Conference or Workshop Item (Speech)
Additional Information:AIAA SciTech Forum; 2018 AIAA Aerospace Sciences Meeting; Copyright 2018 by Armin Weiss; Published by the American Institute of Aeronautics an Astronautics, Inc., with permission; https://scitech.aiaa.org
Title:On the Effect of Rotational Forces on Rotor Blade Boundary-Layer Transition
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Weiss, ArminArmin.Weiss (at) dlr.dehttps://orcid.org/0000-0002-7532-2974
Gardner, Anthonyanthony.gardner (at) dlr.dehttps://orcid.org/0000-0002-1176-3447
Schwermer, TillTill.Schwermer (at) dlr.dehttps://orcid.org/0000-0002-6918-4480
Klein, ChristianChristian.Klein (at) dlr.deUNSPECIFIED
Raffel, MarkusMarkus.Raffel (at) dlr.deUNSPECIFIED
Date:2018
Journal or Publication Title:2018 AIAA Aerospace Sciences Meeting
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
DOI :10.2514/6.2018-0309
Page Range:pp. 1-17
Status:Published
Keywords:boundary-layer transition, helicopter rotor blades, rotational effects, temperature-sensitive paint, e^N ­method
Event Title:AIAA SciTech Forum 2018
Event Location:Kissimee, Florida USA
Event Type:international Conference
Event Dates:07.-11. Jan. 2018
Organizer:American Institute of Aeronautics and Astronautics
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:fixed-wing aircraft
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Simulation and Validation
Location: Göttingen
Institutes and Institutions:Institute for Aerodynamics and Flow Technology > Experimental Methods, GO
Institute for Aerodynamics and Flow Technology > Helicopter, GO
Deposited By: Bachmann, Barbara
Deposited On:20 Mar 2018 15:32
Last Modified:25 Jun 2018 08:41

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