Acoustic interferometer

About: Acoustic interferometer is a research topic. Over the lifetime, 1493 publications have been published within this topic receiving 19355 citations.

Design and fabriction of micro-viscometer using the propagation of acoustic waves in micro-channel

Abstract: A micro-viscometer for measuring viscosity changes in small amount of liquid in real time is designed and fabricated. The merits of the device are to use minimal liquid and to increase the sensitivity for measuring the viscosity. The micro-viscometer is composed of two chambers connected by several micro-channels. Each chamber has a unimorphic piezoelectric diaphragm for driving and sensing sound waves. The micro-channel plays a role as a waveguide and an attenuator of sound waves. Attenuation of sound wave is a function of the viscosity of the liquid. So, the output voltage of sensor is also changed as the viscosity of liquid is changed. After fabrication through micromachining, the device was tested on several viscous liquids, and then it was demonstrated that the device can play a role of a viscometer with high sensitivity. In this paper, we mainly discuss on the comparison between experimental results and newly simulated results.

Direct Fourier Synthesis of Waves: Application to Acoustic Source Radiation

Abstract: In numerous situations of current interest in aeroacoustics the sound field propagates in a nonhomogeneous medium. This is typically the case of jet noise radiation. A widely used model in that situation consists of a thin vortex sheet separating two uniformly moving fluids. This model may be treated as a layered medium, and acoustic source radiation may be analyzed by Fourier transform techniques. The inversion of the Fourier solution is however difficult and requires far-field approximations. This difficulty is here avoided by constructing the wave field by direct Fourier synthesis. This method was shown, in a previous work to be fast, reliable, and superior to the standard approximations. It is applied here to source radiation in the vicinity of a vortex sheet separating uniformly moving streams. Complete wave field maps are given for subsonic and supersonic flow combinations, providing new insights on jet noise radiation and refraction in open wind tunnels.