E. Nienaltowska

Noise generated by an external air flow on car windows isrelated to the intensity of local flow fluctuations. To predicttheir importance and possible reduction one have to betterunderstand the local flow features. For this task newmethods of visualisation and/or data processing arenecessary.This paper is a presentation of our experience in that field.The data obtained by image processing from a video filmconcern two visualisation methods. The first one deals witha tufts motion on the car windows. Two parameters aredefined for statistical treatment of deviation angles.Different classes of perturbation level are distinguished.Corresponding areas for low frequency range are presented.The second method of visualisation using the layer of shearsensitiveparticles which refraction index fluctuated whenthose of a local flow occurred. The "footprint" shown byimage processing accompanies the most important flowfluctuations in the medium frequency range and correspondsto the main noise sources location obtained from acousticdata interpolation.A flow perturbation in large range of frequencies could bedetected by visualisation and may become a new way ofaccess to the parameters governing the noise generation, butfurther progress depends on the reinforcement of statisticalapproach of local fluctuations.

First Joint CEAS/AIAA Aeroacoustics Conference, München, 1995

Conference Paper

englisch

21,0 x 29,7 cm, 6 Seiten

DGLR-Bericht, 1995, 1995-01, First Joint CEAS/AIAA Aeroacoustics Conference - Proceedings; S.429-434; 1995; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

NA

aeroacoustics

Bibliothek

1995