Acoustic interferometer

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

Acoustic waves from a supersonic jet impinging on an inclined flat plate

Abstract: Flow and flow-induced acoustic fields of a supersonic jet impinging on an inclined flat plate is computationally studied. Effects of nozzle-plate distance and jet temperature are discussed as these are important parameters for the estimation of the acoustic wave strength from the engineering viewpoint such as a rocket plume. Three-dimensional compressible Navier-Stokes equations are solved with the modified weighted compact nonlinear scheme for the numerical simulations. Simulation results are analyzed from the viewpoints of acoustic emission and propagation mechanism, and acoustic field characteristics such as directivity, their spectra, and acoustic wave source positions are investigated. Time-averaged pressure contour on the plate shows two pressure peaks that are commonly observed in the jet-plate interaction; one by the jet impingement and the other by the plate shock wave. The acoustic fields indicate that there are at least three kinds of acoustic waves in all the cases considered in the study: (i) Mach waves generated from the shear layer of the main jet, (ii) acoustic waves generated from the impingement region, and (iii) Mach waves generated from the shear layer of the supersonic flow downstream of the jet impingement. Indication of the second one (ii) is important because the commonly-used empirical method for the estimation of the acoustic waves from a rocket plume does not consider such acoustic waves. Directivity and sound pressure level of the acoustic waves (ii) and the Mach waves (iii) change strongly with the temperature increase. Directivity and sound pressure level of the acoustic waves (ii) and the Mach waves (iii) change slightly with the nozzle-plate distance increase. The results show that whether the impinging point is inside or outside of potential core does not strongly affect the characteristics of the induced acoustic waves (ii).

A Guided Acoustic Wave Liquid Level Sensor

Abstract: It is known that the level of a liquid in a tank can be determined from the measurement of the time of flight of acoustic waves propagating in the atmosphere between the transducer and the surface of the liquid. Unfortunately, the propagation of the waves is affected by any variation (pressure. air motion, temperature) of the atmosphere. In order to reduce the effects of these disturbances, we propose to guide the acoustic waves. We report on experiments performed, in a water tank, with cylindrical tube waveguides (diameters 12-14 m). Two modes of flexion, symmetrical and antisyrmnetrical, have been excited by piezoelectric ceramic transducers (ring. bar). The echo from the reflection at the guide-water interface is easily detected.

Effect of acoustic radiation on a spherical drop of liquid

Abstract: The effect of radiation force on a drop of liquid in an acoustic field is examined. It is established that the force depends on the ratio of the densities of the liquid and the drop and on their adiabatic elastic moduli

Substrate penetrating acoustic sensor

Abstract: An acoustic sensor configured to detect sound waves traveling through a substrate in which the acoustic sensor is embedded. The acoustic sensor includes a piezoelectric element and mass configured to receive and react to sound waves in three dimensions. Also, methods of using the acoustic sensor to receive sound waves traveling through a substrate.