Acoustic response characterization of thermoacoustic CNT thin film arrays

Abstract

A new model for a thermoacoustic transducer array with high acoustic beam directivity applying devised carbon nanotube (CNT) thin films is developed. Analytical exact solutions of acoustic pressure field for linear and planar arrays are derived by constructing a new spherical thermoacoustic model. The beamwidth and side-to-main lobe ratios are defined and used as the criteria for determining the optimal array design parameters. The key influencing factors including input frequency, element number, element length and inter-element spacing on the acoustic performance and characteristics are extensively investigated. A comparison between theoretical prediction and experiment is presented to verify the analytical model and very good agreement is reported. The numerical result indicates that increasing the input frequency, element length and inter-element spacing improves the main lobe sharpness while at the same time it lowers the energy efficiency for a fixed element number. It is recommended the largest possible element length, inter-element spacing and element number should be adopted to produce a higher acoustic pressure and better acoustic directivity while meeting the energy efficiency requirement.