Model for thermoacoustic emission from solids

Abstract

A model for the thermoacoustic (TA) emission in both low and high frequency ranges is derived by fully coupled thermal-mechanical analysis. Accordingly, it has been theoretically confirmed that there exists a very wide range of constant (flat) amplitude-frequency response mostly in ultrasonic region for TA emission from any solid, and its existence conditions and frequency range as well as calculation formula are clarified and particularly given. The theory developed in this work agrees well with the experimental results, and is applicable to a variety of TA emission problems.

Solution for acoustic field of thermo-acoustic emission from arbitrary source

“…[2][3][4][5][6][7][8][9][10][11][12][13] However, theoretical investigation of TA emission seriously lags behind the experimental one due to comparatively fewer efforts. Currently, alomast all the formulas for calculating TA emission so far are one-dimensional, 1,[14][15][16][17]19,22 taking advantage of the plane-wave solution based on the pressure-temperature coupled equations in a fluid given by F. A. McDonald and G. C. Wetsel, Jr., 18 and the problems of near-and far-field TA emission need to be dealt with seperately. The multi-dimensional TA emission problems, e.g.…”

Gap separation effect on thermoacoustic wave generation by heated suspended CNT nano-thinfilm

“…Here subscript 2 indicates parameters that are related to the substrate. The thermal diffusion length of thermal wave is ffiffiffiffiffiffiffiffiffiffiffiffiffiffi 2a 2 =u p [4,21,22,25], hence thermally-thick condition is readily satisfied for the substrate. By using no reflection boundary condition, the thermal wave sharply attenuates before arriving at the back of substrate.…”

“…Hu et al [21] proposed a fully coupled thermal-mechanical model to analyze thermally induced ultrasound generation using porous silicon. Xiao et al [5] improved the piston model proposed by Arnold and Crandall [1] to explain their experiment result and it was first claimed that the conductor HCPUA was the key factor to upgrade practical applications of any thermoacoustic devices.…”

Comparison of three-dimensional photoacoustic effect with different Gaussian radii

“…Take the simulated data into the above expression, = 0.2858 ×10 5 Hz, = 1,2,3, ⋯ coincided with the results. We can see the resonance frequency is proportional to isentropic sound velocity and inversely proportional to photoacoustic cell length.…”

“…McDonald and Wetsel [3] established the thermoelastic coupled equations and given the first order approximate solution. Hanping Hu [4,5] considered photoacoustic coupled equations of multilayer materials and derived the analytical solution. All of these sound is generated within the gas layer and detected by acoustic transducer in the surrounding gas, but Gu Liu [6] considered both heat and photoacoustic signal are generated and detected within the same solid or liquid.…”