Multilayer modeling of thermoacoustic sound generation for thermophone analysis and design

Guiraud, Pierre; Giordano, Stefano; Bou-Matar, Olivier; Pernod, Philippe; Lardat, R.

doi:10.1016/j.jsv.2019.05.001

Cited by 22 publications

(50 citation statements)

References 38 publications

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“…While the detailed proof of Eqs. (39) and (40) is given in the recent literature, 20 it is worth noticing that these results represent the first order expansions (with small κ, λ and µ) of the solutions of the algebraic equation associated with Eq. (31).…”

Section: Backmentioning

confidence: 67%

“…On the other hand, it is important to also note that in this thermophone model the heating of the air is a process distributed (although not continuously) within the whole region of the generation layer (at all the air/foam contacts) and not only at the external interfaces (at x 1 and x N+1 ) as in the classical thermophone models. 20 For this reason, it is able to represent the behavior of thick and porous thermophone devices.…”

Section: Backmentioning

confidence: 99%

“…coherently with recent investigations. 20 The solutions of Eq. 31represent thermal modes and acoustical modes that will be described by θ th and k ac , respectively.…”

Section: Backmentioning

confidence: 99%

“…Indeed, at this distance, the velocity has attained its maximum value, which can be considered for the acoustic propagation in Eq.(58). The thickness of the thermal layer has been evaluated through the approximated expression 20 Hence, the theoretical curves that will be shown in Section IV represents the results of the Rayleigh's second integral applied to the velocity field of our near field model. In other words, our model is used to describe the thermoacoustic generation of waves whereas the diffraction theory is used to properly take into account the resulting acoustic propagation.…”

Section: Backmentioning

confidence: 99%

“…19 Lastly, a multilayer model taking the wave propagation in the solid thermophone layer into account has been proposed. 20 In most models, the generating thermophone layer is considered as a homogeneous solid material. Consequently, the performances of the device are typically written in terms of the so-called heat capacity per unit area (HCPUA), which is defined as the product of the thickness of the layer L l , its density ρ s , and its heat capacity C v,s .…”

Section: Introductionmentioning

confidence: 99%

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Two temperature model for thermoacoustic sound generation in thick porous thermophones

Guiraud

Giordano

Matar

et al. 2019

Journal of Applied Physics

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The thermoacoustic sound generation offers a promising wideband alternative to mechanically driven loudspeakers. Over the past decade, the development of nanomaterials with new physico-chemical properties promoted a wide interest in the thermophones technology. Indeed, several thermophone structures based on suspended nanowires, graphene sheets, highly porous foams or sponges have been investigated. At the same time, theoretical models have been developed to predict the frequency and power spectra of these devices. However, most of models have taken into consideration a solid homogeneous material for representing the thermophone generating layer, and its microstructure was therefore neglected. If this assumption holds for thin dense materials, it is not acceptable for thick and porous thermophone devices. Hence, a model able to describe the behavior of highly porous foam-or sponge-like generating layers is proposed. It is based on a two temperature scheme since the thermal equilibrium is not typically attained between the foam material and the embedded air. To do this, the fluid equations for the air are coupled with the heat equation for the solid foam through boundary conditions mimicking the energy exchange at the contact surface between them. The behavior of the main physical variables within the porous generating layer is explained and comparisons with recent experimental results are thoroughly discussed.

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Section: Backmentioning

confidence: 67%

Section: Backmentioning

confidence: 99%

“…coherently with recent investigations. 20 The solutions of Eq. 31represent thermal modes and acoustical modes that will be described by θ th and k ac , respectively.…”

Section: Backmentioning

confidence: 99%

Section: Backmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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