Noise produced during normal impingement of a compressible vortex ring on a flat surface is studied in the shock-Mach number (M) range of 1.31 to 1.55. The compressible vortex ring is generated at the open end of a short driver section shock tube. The far-field noise is decomposed into three major components; (i) sound field due to formation and evolution of the vortex ring, (ii) reflected shock and vortex ring interaction noise and (iii) noise due to impingement of the ring on the wall. The impingement noise consists of fluctuating pressure due to deformation and stretching of the vortex ring, formation and growth of a secondary wall vortex ring, lifting-off of the primary-secondary vortex ring pair. All these events are identified using discrete wavelet transform (DWT) of the sound pressure signal and verified with the laser sheet based flow visualizations. Acoustics fluctuations measured at different angular location shows that the noise due to wall-vortex ring interaction is dominant at 10° ≤ θ ≤ 40°.
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