Measurement of sound source distribution around a circular cylinder in a uniform flow by combined particle image velocimetry and microphone technique

Aeolian Tone from a Semi-Circular Cylinder in a Stream

“…Since then, the experimental and numerical studies on the unsteady flow field and the aerodynamic sound from the circular cylinder have been carried out to explore the mechanism of the sound generation from the circular cylinder in a uniform flow [4]- [12]. It should be mentioned that the sound sources of the Aeolian tone are known to be located around the separation points and along the separating shear layer, which are measured by particle image velocimetry combined with microphone technique [12].…”

“…It should be mentioned that the sound sources of the Aeolian tone are known to be located around the separation points and along the separating shear layer, which are measured by particle image velocimetry combined with microphone technique [12].…”

Measurement of Aerodynamic Sound Source around a Circular Cylinder by Particle Image Velocimetry

“…A variety of experimental methods for localizing the sound sources have been proposed in literature, such as the acoustic impedance method [7], microphone array method [8], cross-correlation method [9]- [11], and the method using time-resolved particle image velocimetry (PIV) [12] [13]. Among these experimental methods, the last two methods allow for localization of the aerodynamic sound sources because they can evaluate simultaneously the velocity field, which supports the understanding of the generation mechanism for aerodynamic sound.…”

“…The cross-correlation method analyzes the relationship between velocity fluctuations in the near field and the sound pressure fluctuation in the far field of a circular cylinder. This method relies on the acoustic analogy that the sound source intensity is proportional to the vector product of vorticity and velocity in the flow field [10] [11]. The other approach is the evaluation of the cross-correlation between the fluctuating static pressure fluctuation and the sound pressure fluctuation emitted from a bluff body [11].…”

“…This method relies on the acoustic analogy that the sound source intensity is proportional to the vector product of vorticity and velocity in the flow field [10] [11]. The other approach is the evaluation of the cross-correlation between the fluctuating static pressure fluctuation and the sound pressure fluctuation emitted from a bluff body [11]. On the other hand, the method using time-resolved PIV provides the time-series data of instantaneous velocity field, which allows the evaluation of time-derivative of the vector product of vorticity and velocity in the flow field [12] and the evaluation of the pressure fluctuation on the cylinder surface [13].…”