K. Pengel

The DNW uses the laser light sheet method for investigations of the flow around wind tunnel models. Cylindrical lenses or rotating mirrors are used to generate the light sheet from the laser beam. The application described in this paper requires the use of a rotating mirror. In this way, extremely short exposure times of the smoke particles can be realized. A 30 Hz beam sweeping frequency leads to an illumination time of 1 µs for every particle which has a 3m distance from the mirror. In this manner instantaneous images of a periodically changing flow are obtained and recorded with a video system. From these video images Strouhal numbers St are determined. For this determination lengths from single video pictures have to be measured. That is done by means of digital image processing, performed by the DFVLR Institute for Experimental Fluid Dynamics Gottingen. An example will be discussed in this paper, namely the wake vortices of an outdoor mirror. The frequency of the noise, generated by this mirror, was derived from flow visualization pictures.

DGLR-Workshop, Markdorf, 1988

Conference Paper

englisch

21,0 x 29,7 cm, 6 Seiten

DGLR-Bericht, 1988, 1988-04, 2D-Meßtechnik; S.105-110; 1988; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

NA

aerodynamics

Bibliothek

1988