THERMOACOUSTIC PERFORMANCE OF CARBON NANOTUBE SHEETS

Thin carbon nanotube (CNT) sheets are excellent materials for small thermoacoustic (TA) devices. They are strong, lightweight, and can be used to produce sound efficiently through high frequency temperature fluctuations. These TA devices have the potential to be used in active noise cancellation, or as SONAR projectors for very small unmanned underwater vehicles. This thesis aims to evaluate the TA performance of CNT sheets and compare them to theoretical calculations and to other state-of-the-art TA materials. The CNT sheets tested were two Miralon® sheets provided by Nanocomp; one with a density of 10–15 grams per square meter and another with a density of 20–30 grams per square meter. Performance was evaluated based on sound pressure level (SPL) recorded over a frequency range of 500 Hz to 100 kHz. The lower-density sheet was found to have the better performance of the two. Further testing showed that this lower-density sheet has comparable TA performance to other CNT-based materials used for thermophones. The Miralon® sheets are a viable material for use in thermophones and other thermoacoustic devices such as lightweight SONAR projectors.http://archive.org/details/thermoacousticpe1094564158Ensign, United States NavyApproved for public release; distribution is unlimited