| Fibrous materials have been used successfully as the stack element in thermoacoustic devices but analysis and measurement of all the thermoacoustic properties has not been performed successfully. The acoustic thermoviscous functions that characterize the material can be measured experimentally, but the gain component of the thermoacoustic wave equation has proven difficult to measure [Simmons, 2003]. A theory has been proposed [Roh, 2007] that predicts the gain coefficient from the thermoviscous functions but it has not been tested experimentally. For the present work, a computational method has been developed for thermoacoustics in a three-dimensional stack element that has been validated successfully against analytical solutions for parallel pored stack geometries. The simulated results for a fibrous geometry are compared against the predicted thermoacoustic gain coefficient and it is found that the theory matches well for the imaginary component, but that the real component is larger than the theory predicts. This suggests that the theory underestimates the gain for a fibrous stack in a traveling wave device while being a good approximation for standing waves.;Simmons, T. (2003). Experimental Determination of Thermoacoustic Stack Properties. PhD Dissertation: University of Mississippi;Roh, H.S., Raspet, R., Bass, H.E. (2007). J. Acoust. Soc. Am ., 121(3), 1413-1422... |
