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

Abstract

In this work, an expression for acoustic field of thermo-acoustic (TA) emission from arbitrary source is presented by deriving the solutions of TA emission from spherical surface and point source in gas and then taking advantage of the point sources superposition and the surface heat distribution factor. Accordingly, the computational analysis of acoustic pressure field of TA emission is extended to three-dimensional cases. The theory developed in this work is in good agreement with the experimental results and applicable for solving many complex and important TA emission problems including nanothermophones and phased array and impulse-driven TA emissions.

Emerging Functions of Nanostructured Porous Silicon—With a Focus on the Emissive Properties of Photons, Electrons, and Ultrasound

“…Regarding thin metal film heaters and underlying thermal insulators, many studies have been conducted by using varied combinations: suspended Al wires-air (Niskanen et al, 2009), Si nanowires-polymer or -glass (Tian et al, 2011a), indium-tin-oxide film-glass (Daschewski et al, 2015), Si nanoparticles-sapphire (Odagawa et al, 2010), conducting polymers-glass (Tian et al, 2011b), thin Au film-porous polymer (Chitnis et al, 2012), thin Ag–Pd film-glass-Al 2 O 3 (Nishioka et al, 2015), carbon nanotube (CNT)-air (Xiao et al, 2011), or -grooved Si (Wei et al, 2013), graphene-polymer (Suk et al, 2012; Tian et al, 2014; Kim et al, 2016; Tao et al, 2016; Sbrockey et al, 2018), -porous Al 2 O 3 (Tian et al, 2012), or -glass (Fei et al, 2015), CNT-laser-scribed graphene-polymer (Yeklangi et al, 2018), and W-Al 2 O 3 -polymer (Brown et al, 2016). The basic characteristics of these devices are consistent with the theoretical analyses of the thermo-acoustic effect and its key factors (Hu et al, 2010, 2012a,b, 2014; Vesterinen et al, 2010; Daschewski et al, 2013; Lim et al, 2013; Yang and Liu, 2013; Wang et al, 2015; Tong et al, 2017; Xing et al, 2017). Making use of the non-resonant and broad-band emissivity with no harmonic distortions, possible applications have been pursued to audible compact speaker under a full digital drive, probing source for 3-dimentional object sensing in air, acoustic pressure generator for noncontact actuation, directivity control under phased array configuration, loud speaker, noise cancellation, thermoacoustic tomography, and thermoacoustic sound projector (Koshida, 2017c; Aliev et al, 2018; Bobinger et al, 2018; Julius et al, 2018; Liu et al, 2018; Song et al, 2018).…”

On the Frequency Response of Nanostructured Thermoacoustic Loudspeakers

“…Moreover, the pressure response is scaled accordingly to the distance and the air TA coefficient . The latter, as also reported in previous studies [ 15 ], relates the heat flow injected into the air to the induced air mass flow due to thermal expansion, which is key for the generation of the pressure wave [ 24 ].…”

“…Nevertheless, most of the latest studies focused on the evaluation of the performance enabled by the new materials, often overlooking the physical phenomena underlying TA sound generation. While the full electro-acoustic transduction of TA loudspeakers is widely documented in the literature [ 1 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ], the thermal response of TA loudspeakers to the applied electrical stimuli and its role in determining the acoustic response were investigated superficially in the past.…”

Thermo acoustic study of carbon nanotubes in near and far field: Theory, simulation, and experiment

“…17 Some have used temperature variations of either sound source or medium in one dimensional domain and then have ascribed the pressure to the temperature variations, 1,3 which requires some assumptions and simplifications.…”