H. Holthusen, J.W. Kooi

The German-Dutch Wind Tunnel DNW is a large lowspeed wind tunnel with three different sized closed andone open test section (Open Jet). Already during the firstcalibration phase of the Open Jet in 1981, it became clearthat the maximum jet velocity was not limited by theavailable fan power, but by the maximum allowablevibrations of the Test Hall, which surround the Open Jet.Due to low-frequency noise generated by the Open Jet,the Test Hall reaches a dangerous level of vibration at ajet velocity of 80 m/s. In order to be able to increase themaximum velocity an extensive research programme wasexecuted in the 1: 10 scaled pilot wind tunnel of DNW. Theobjective of this programme was to find the sources of theobserved low frequency noise and to test configurationchanges for their potential to reduce the vibration level.The tested configurations included a number of well-knownnozzle modifications as well as a new configuration withso-called tetrahedrons. Also the effect of modifications ofthe collector geometry and the effect of extra bleeding wasinvestigated. After completing the tests in the pilot windtunnel, the most promising solutions were tested in theDNW. It turned out that the results found in the two windtunnels correlated very well. A surprising outcome was,that in both tunnels the tetrahedrons increased the speedwithout a dramatic reduction of the usable cross section ofthe Open Jet or without increasing the acoustic backgroundnoise.

First Joint CEAS/AIAA Aeroacoustics Conference, München, 1995

Conference Paper

englisch

21,0 x 29,7 cm, 10 Seiten

DGLR-Bericht, 1995, 1995-01, First Joint CEAS/AIAA Aeroacoustics Conference - Proceedings; S.419-428; 1995; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

NA

aeroacoustics, wind tunnel

Bibliothek

1995