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Application of the eN method of linear boundary layer stability theory to a natural laminar flow engine nacelle

Riedel, H. and Sitzmann, M. (2015) Application of the eN method of linear boundary layer stability theory to a natural laminar flow engine nacelle. DLR-Interner Bericht. DLR-IB 124-2015/1, 45 S.

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Abstract

A stability analysis of the laminar boundary layer on a natural laminar flow engine nacelle flight tested on the DLR VFW614/ATTAS is performed. Since the flow on this nacelle is effectively two-dimensional, only the flow transition due to Tollmien-Schlichting waves is considered. The e^N method of the local linear boundary layer stability theory is applied to determine the limiting N factors N_LIM for various flight Mach numers Ma and chord Reynolds numbers Rec making use of the SALLY code. The flight trials covered a flight Mach number regime 0.26 < Ma < 0.59 and the nacelle fan cowl chord Reynolds number range was 5.5x10hoch6 < Rec < 8.9x10hoch6. Key objective of the analysis was the determination of the effect of flight and engine operating conditions on the calculated limiting N factor. The results of the investigation show that the type of external surface static pressure distribution on the nacelle fan cowl has a marked effect on the magnitude of the limiting N factor. A comparison of the limiting N factors for the VFW614/ATTAS natural laminar flow nacelle flight tests with those from flight trials of a natural laminar flow wing glove on the VWF614/ATTAS and the LFU205 shows for the nacelle the value of N_LIM with N_LIM = 9-10 to be lower by DeltaN_LIM = 4-5 than for the wing glove cases for the same flight Mach number and transition Reynolds number ranges.

Item URL in elib:https://elib.dlr.de/98024/
Document Type:Monograph (DLR-Interner Bericht)
Title:Application of the eN method of linear boundary layer stability theory to a natural laminar flow engine nacelle
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Riedel, H.UNSPECIFIEDUNSPECIFIED
Sitzmann, M.martin.sitzmann (at) dlr.deUNSPECIFIED
Date:2015
Refereed publication:No
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Number of Pages:45
Status:Published
Keywords:Natural laminar flow engine nacelle, stability analysis, Tollmien-Schlichting waves, eN method, flight tests
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 - Flight Physics
Location: Braunschweig
Institutes and Institutions:Institute of Aerodynamics and Flow Technology > Transport Aircraft
Deposited By: Seyfried, Beate
Deposited On:31 Aug 2015 14:40
Last Modified:31 Aug 2015 14:40

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