In order to study the effects of turbulence on aerodynamic noise generation, a low-noise active turbulence generator was developed and noise measurements were carried out. A large-scale turbulence field such as atmospheric turbulence can be obtained using our active turbulence generator. The energy spectrum of turbulence generated by the present generator had an inertial subrange and the turbulence Reynolds number was over 300. To reduce the aerodynamic noise from the active turbulence generator itself, a passive silencer and pile fabrics were installed. In addition, the oscilating mode of the agitator wings was controlled with a pulse motor. As a result, the noise level of the background noise was reduced to 64 dB(A), which is only 10 dB larger than for a conventional wind tunnel. The noise from the rearview mirror was measured in both laminar and turbulent flows using the active turbulence generator. The tonal-noise is reduced with incoming flow turbulence. On the other hand, the broadband noise of the rearview mirror increases in the case of turbulent incoming flow. The wuthering noise of turbulence and unsteadiness of the tonal-noise in actual situations can be simulated by using the present active turbulence generator. These results indicated that the active turbulence generator is suitable to study the effects of turbulence on aerodynamic noise generation. Incoming flow turbulence is therefore an important parameter for the development of comfortable, low-noise automobiles.
Effect of incoming flow turbulence on aerodynamic noise radiated from automobiles
Einwirkung der eintretenden Strömungsturbulenz auf aerodynamischen Automobilgeräusch
Review of Automotive Engineering (JSAE) ; 27 , 4 ; 565-570
2006
6 Seiten, 7 Bilder, 1 Tabelle, 7 Quellen
Article (Journal)
English
Fahrzeugaerodynamik , Fahrzeuggeräusch , Anwendung im Fahrzeugbau , laminare Grenzschicht , Strömungstechnik , Strömungsvorgang , turbulente Strömung , Luftströmung , Reynolds-Zahl , Schallpegel , atmosphärische Turbulenz , Schalldämpfer , Schwingungsmode , Geräuschmessung , Energiespektrum , Außenspiegel , laminare Strömung , Pkw (Personenkraftwagen)
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