Shock-Vortex Interactions And Sound Production

The interactions of shock waves with turbulent flows is known to be one of the major sources of noise,and so closely related to variety of aerodynamic problems such as noise producted by rockets, high-speed aircraft and helicopters. Vortex is the basic structure of turbulance. thereby, investigation of shock-vortex interactions is important to shock-turbualnce phenomenon. During the interaction of shock-vortex,shock is deformed and sound wave is produced. In this paper the interaction of a shock wave with a cylindrical vortex was studied. The objective of the study is to characterize the shock deformations and the mechanism of sound generation. The approach relies on the solution of the two-dimensional Euler equations by means of a two order finite volume MUSCL-Hancock scheme. A systematic study has been conducted by investigating the effects of vortex intensity and shock strength. According to the shock and vortex strength, there are three types of shock deformations:weak interactions, strong interactions with a Mach reflection pattern and strong interactions with a regular reflection pattern. The acoustic field generated through shock-vortex interactions has been found to evolve in three stages and to exhibit a three sound quadrupolar directivity. In the early stages of the interaction the sound generated due to shock distortion shows a dipolar character, which then changes to a quadropolar one due to a restoring mechanism that acts during the interaction of the shock with the rear part of the vortex. In the third stage secondary sounds are formed, which also show a quadropolar directivity. At last, third sounds are formed. Finally, in order to understand the difference between circular shock-vortex and plane shock-vortex interactions.Blast wave-vortex interactions was simulated. Numerical results show that the shock deformation structures in the former case is similar with the latter one.