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STUDY ON AERODYNAMIC SOUND GENERATION BY VORTEX MOTIONS IN A CIRCULAR JET

Riho Hiramoto
Department of Mechanical Systems Engineering, Hokkaido Institute of Technology Maeda 7-15-4-1, Teine-ku, Sapporo 006-8585, Japan

Kuniaki Toyoda
Department of Mechanical Systems Engineering, Hokkaido Institute of Technology Maeda 7-15-4-1, Teine-ku, Sapporo 006-8585, Japan

Hayato Mori
Department of Mechanical Systems Engineering, Hokkaido Institute of Technology Maeda 7-15-4-1, Teine-ku, Sapporo 006-8585, Japan

Resumo

Simultaneous measurements of velocity and fluctuating static-pressure were carried out in an air jet issuing from a sharp-edged circular orifice, and the sound source terms of vortex sound theory and dilatation theory were discussed in relation to the vortex motions. The jet was excited in the interaction mode so that velocity and fluctuating static-pressure can be determined in space and time domains by using phase-average technique. The sound source terms of the theories were obtained from the phase-average velocity and fluctuating static-pressure via the differential process in space and time. The result suggests that intense sound sources are caused by the vortex merging and by the acceleration of vortices during vortex pairing. In addition, it is noted that the regions of intense sound source are different from those of intense fluctuating-velocity and -pressure.