Abstract
Impinging planar jet upon a wedge gives rise to self-sustained oscillations, which is called edge-tone. This oscillation phenomenon and the edge-tone cause vibration and noise in machinery, then their control is industrially important. The purpose of this study is to reveal the role of sound transmission of blocking plate and the entrainment near the nozzle exit in the edge-tone. In this study, we used a pair of blocking plate attached near the nozzle exit in order to estimate the above mentioned role. The sound transmission was changed by the material and thickness of blocking plate. The entrainment near the jet exit was changed by the attachment direction of blocking plate. As the result of the sound and velocity measurement in the flow field, it is clarified that the edge-tone is generated when the good sound transmission plate is attached regardless of the attachment direction of the blocking plate. Therefore, it is clarified that the feedback of pressure fluctuation is more important than the entrainment near the nozzle exit to maintain the edge-tone phenomenon.
