Research Papers

Thermal-Acoustic Wave Generation and Propagation Using Suspended Carbon Nanotube Thin Film in Fluidic Environments

[+] Author and Article Information
P. Jia

Department of Architecture and
Civil Engineering,
City University of Hong Kong,
Kowloon, Hong Kong, China

C. W. Lim

Department of Architecture and
Civil Engineering,
City University of Hong Kong,
Kowloon, Hong Kong, China
e-mail: bccwlim@cityu.edu.hk

1Corresponding author.

Contributed by the Applied Mechanics Division of ASME for publication in the JOURNAL OF APPLIED MECHANICS. Manuscript received May 10, 2016; final manuscript received June 13, 2016; published online July 1, 2016. Assoc. Editor: Kenji Takizawa.

J. Appl. Mech 83(9), 091007 (Jul 01, 2016) (9 pages) Paper No: JAM-16-1234; doi: 10.1115/1.4033893 History: Received May 10, 2016; Revised June 13, 2016

A simplified analytical pressure solution for thermal-acoustic wave response generated by using suspended multiwall carbon nanotube (MWCNT) thin film in different fluidic environments is developed. The solution consists of two independent portions: the near-field solution and the far-field solution. The electricity power input is a key element to control the thermal-acoustic wave pressure level. The dependence of the solution on axial distance from the source origin is investigated for different fluidic environments. Comparison between analytical solutions and published experimental results is presented, and excellent agreement is reported. A number of numerical examples for different parameters are studied for various liquids and gases including air, argon, water, and ethanol. Accurate analytical approximations for the thermal-acoustic wave response, and amplitude functions for different temperatures in fluids of varying densities are proposed here. The relation of Rayleigh distance and critical frequency has been determined in order to enhance and optimize the thermal-acoustic effect and wave behavior in fluids. These two parameters can be modified by suitable choices of the size of thin film, the properties of surrounding media, etc. The thermal-acoustic generation properties including the electric power input, frequency, and the suspended MWCNT thin film size significantly affect the acoustic pressure performance. It is concluded here that this extended analytical work not only agrees better with experiment but also offers more convincing analytical prediction for the generation and propagation of thermal-acoustic wave in different fluids.

Copyright © 2016 by ASME
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Fig. 1

(a) Configuration of underwater acoustic measurement in the experiment [14] and (b) thermal-acoustic wave propagation in fluidic environments

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Fig. 2

Validation of |d1|≪|d2| and |d1σ1|≪|d2σ2| for increasing frequency at 25 °C in fluidic environments, in (a) liquids: water and ethanol and in (b) gases: air and argon

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Fig. 3

The applicability of e−|Re[σ2]|x|x=0.085m with respect to varying frequencies for fluidic environments, air, argon, helium, water, methanol, and ethanol. The temperature is 25 °C, and the immersed depth is 0.03 m for the case of liquid environments.

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Fig. 4

The thermal-acoustic far-field wave response (x≥R0(f)|f=50,000Hz) with respect to temperature for a single-layer suspended MWCNT sheet immersed underwater at a depth of 0.03 m from the free surface and at a distance of 0.085 m from the source

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Fig. 5

Far-field thermal-acoustic wave response, x≥R0(f)|f=100,000Hz, for varying frequencies with respect to temperature for a single-layer suspended MWCNT sheet, immersed underwater at a depth of 0.03 m and at a distance of 0.085 m from the surface

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Fig. 6

Near-field thermal-acoustic wave response, x≤R0(f)|f=30,000Hz, for increasing power input underwater at different surrounding temperatures. The distance from the center of MWCNT thin film is 0.02 m with the immersed depth of 0.03 m.

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Fig. 7

(a) Thermal-acoustic frequency response in near-field (x≤R0) and far-field (x≫R0) for (a) water at 25 °C, and (b) ethanol at 19 °C, at 0.0025 m, 0.01 m, 0.03 m, and 0.3 m from the source. For (a), the thin film has an area of 0.000742 m2 and immersed underwater at a depth of 0.0075 m. For (b), the area is 0.000572 m2, and the depth is 0.03 m. For (a), the theoretical solution available in Aliev et al. [14] is only for near-field, while none is available for (b). The power input for water is 287 W, while for ethanol it is 395 mW.

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Fig. 8

Thermal-acoustic frequency response for air at 25 °C, at distance 0.65 m and with a size 0.0116 m2, x≤R0(f)|f=19,444 Hz in near-field and x≫R0(f)|f=19,444 Hz in far-field

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Fig. 9

(a) The fluidic thermal-acoustic wave frequency response in water at different hydrophone locations at a depth of 0.03 m and at distances 0.0003 m, 0.003 m, 0.03 m, and 0.3 m. (b) The thermal-acoustic wave frequency response in air, the hydrophone is planted at distance of 0.0001 m, 0.001 m, 0.01 m, and 0.1 m. (c) The thermal-acoustic wave response with varying distances in water and ethanol, at 25 kHz, 50 kHz, and 100 kHz, and in (d), the response in air and argon. For all the cases, the temperature is at 25 °C, and the area is 0.001 m2. The power input for liquids in (a), (b), and (c) is 287 W, while the power input for gases in (d) is 4.5 W.




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