H. Bieler, J. Preist

Laminar flow technology is considered to be the single technology with the largest gain in terms of fuel efficiency. The application of passive laminar flow technology, which is based on suitably designed wing shapes only, has certain limits with respect to sweep and Reynolds-number. However a large pool of experience exists. For example, sailplane wings are NLF wings. The german research programme "Transonic Laminar Wing" [1) showed, that for commercial aircrafts at transsonic cruise Hybrid Laminar Flow Control (HLFC) is necessary. Presently, the wing flow for wide body aircrafts is compietely turbulent (Fig.l). Within the EC-programme BRITE/EU RAM, where several universities, research establishments and the aeronautical industry work closely together, the project ELFIN [2) tackles several laminarity problems including HLFC. In this context a test programme in the ONERA SIMA wind tunnel on a modified ATTAS glove, equipped with a suction system has been scheduled for March 92. The design of the glove and the suction system has been supported by linear stability theory which predicts the onset and development of Tollmien-Schlichting and cross flow type instabilities as a function of mean suction velocities. One real challenge of HLFC is to convert these numerically predicted suction distributions to realistic engineering solutions, i.e. suction flow through a large number of tiny holes in a laser drilled Titanium panel. The first European HLFC test is supposed to be a proof of the HLFC concept, whereas suction flow optimization and many other topics will require future research effort. More knowledge of pressure drops, equivalent roughness of sucked streamtubes and a detailed data base for the development of transition criteria are examples of the kind of results desired from this test campaign.

First European Forum on Laminar Flow Technology, Hamburg, 1992

Conference Paper

englisch

21,0 x 29,7 cm, 8 Seiten

DGLR-Bericht, 1992, 1992-06, First European Forum on Laminar Flow Technology; S.193-200; 1992; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

NA

aerodynamics, boundary layer transition, laminar flow

Bestellbar

1992