F. Anselmet, E. Mérigaud, L. Fulachier

The aim of the present experlmental Investigation is to analyze the effect of suction through an Isolated hole on flat plate boundary layer transition. In order to determine whether there is an optimal dimension and to define suction rate limits. Experiments are performed In the IMST low-speed water tunnel with laser Doppler velocimetry and flow visualizations. The stabilizing effect of suction is investigated through streamwise velocity variances normalized with the free-stream velocity. It is found that fluctuations are first reduced and then enhanced when suction is increased, which allows the determination of admissible suction rates At these values depend on the hole diameter D and our experiments show that diameters need to be smaller than a limit diameter which is about the boundary layer displacement thickness [delta]l to allow transition delay. From analogies between the height of stream tubes deviated towards the wall by suction and an equivalent roughness element. semi-empirical expressions are deduced giving At as a function of D/[delta]l. Good qualitative agreement Is found with present results as well as with previous ones.

First European Forum on Laminar Flow Technology, Hamburg, 1992

Conference Paper

englisch

21,0 x 29,7 cm, 6 Seiten

DGLR-Bericht, 1992, 1992-06, First European Forum on Laminar Flow Technology; S.67-72; 1992; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

NA

aerodynamics, boundary layer transition, laminar flow

Bestellbar

1992