Analysis on Acoustic Characteristics of Aerodynamic Sounds from Surface Irregularities
Akio SAGAWA,
Chief Researcher, Vehicle Noise & Vibration Lab., Fundamental Research Division
Jun MATSUO,
Researcher, Vehicle Noise & Vibration Lab., Fundamental Research Division
Eiichi MAEBASHI,
Engineer, Intellectual Property, Technical Support Division
Yasufumi SUZUKI,
Manager, Vehicle Noise & Vibration Lab., Fundamental Research Division
Aerodynamic noise is generated by irregularities on the surface of a car body as well as the equipment on a car roof. This paper presents analytical results of acoustic characteristics of sounds radiating from surface irregularities and measured results of aerodynamic sounds generating from simplified irregularities on a flat surface. The analytical results show that interference occurs through reflection of dipole sounds originating from irregularities on the base plane. Such a phenomenon has been verified actually by measured data from low-noise wind tunnel tests.