Scattered waves generated by shock wave and vortex ring interaction

Scattered waves generated by interaction of a vortex ring and a shock wave are studied experimentally and theoretically. Acoustic pressure is detected by microphones. A polar diagram of the acoustic pressure (with respect to time) constructed from the detected signals shows the waves clearly and the angular distribution of the acoustic pressure is captured visually. Mechanism of noise generation is also investigated. Theoretical formulation for sound scattering by vortex field is applied to describe shock-vortex interaction. Forms of the waves generated by the interaction are calculated by using the velocity field of a typical incident spherical shock wave and compared with the experimental data. Sound scattering by the density inhomogeneity inside a vortex core is also estimated. Some characteristic features of the scattered waves are described. (C) 2000 The Japan Society of Fluid Mechanics and Elsevier Science B.V. All rights reserved.