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Passive Shock Control Concept for Drag Reduction in Transonic Flow

Dietz, G. (2005) Passive Shock Control Concept for Drag Reduction in Transonic Flow. Journal of Aircraft, Vol. 42 (No. 3), pp. 794-798.

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Abstract

The operating principle of a novel passive shock control concept for drag reduction on swept wings called D-Strips is introduced, and results of a first experimental proof of concept are presented. Wind-tunnel experiments are conducted at transonic airspeeds using an airfoil VC-Opt (9.2% relative thickness) with forced boundary-layer transition. Schlieren pictures confirm the operating principle. Wake measurements demonstrate that, locally, in the wake of D-Strips the total drag increases. However, more globally, at spanwise locations away from these positions the total drag is measurably reduced if a sufficiently strong shockwave is present above the wing-suction-side surface. In contrast to passive control by ventilation, outside of the wake of the D-Strips a wave and viscous drag reduction and observed. Furthermore, the maximum lift tends to be increased by D-Strips suggesting that the buffet-onset limit is delayed. An application of D-Strips to a swept wing at cruise conditions can yield net aircraft drag reduction because the drag rise is limited to the D-Strips and its wake, but the shock-weakening effect and the drag reduction are distributed in the wide-splayed characteristics upstream of the shock front. The effectiveness of D-Strips is less sensitive to the location of the shock wave than control concepts like two-dimensional bumps, which are only effective at the design conditions. Another application of D-Strips that can be considered is the regions with a distinct shock, for example, between engines or in the wing-root region or at the inboard engine. However, there is a need for further investigations in order to optimize D-Strips and to quantify their impact on aircraft performance. Recent experimental results indicate that airscoop-type configurations might perform better as D-Strips than Velcro-type strips. Because D-Strips are easy to apply on existing wings, an application of D-Strips for retrofit is possible.

Item URL in elib:https://elib.dlr.de/14547/
Document Type:Article
Additional Information: LIDO-Berichtsjahr=2005,
Title:Passive Shock Control Concept for Drag Reduction in Transonic Flow
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Dietz, G.UNSPECIFIEDUNSPECIFIED
Date:2005
Journal or Publication Title:Journal of Aircraft
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:Yes
Volume:Vol. 42
Page Range:pp. 794-798
Status:Published
Keywords:flow control, transonic flow, drag reduction
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Aeronautics
HGF - Program Themes:other
DLR - Research area:Aeronautics
DLR - Program:L ST - Starrflüglertechnologien
DLR - Research theme (Project):UNSPECIFIED
Location: Göttingen
Institutes and Institutions:Institute of Aeroelasticity
Deposited By: Erdmann, Daniela
Deposited On:16 Sep 2005
Last Modified:14 Jan 2010 21:59

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