Influence of feedback loop charateristics on the performance of a travelling wave thermoacoustic engine

J. H. Goh¹ - Y. A. Abakr¹ - D. B. Hann²

¹ Department of Mechanical, Manufacturing and Materials Engineering, The University of Nottingham Malaysia Campus, Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan, Malaysia
² Department of Mechanical, Manufacturing and Materials Engineering, The University of Nottingham, University Park, Nottingham, NG7 2RD, UK

Abstract
A method to find experimentally the equivalent effective length of the Thermoacoustic (TA) core of a TA Engine (TAE) is proposed. The TAE is first operated with various Feedback Loop (FL) length configurations. For every configuration, the frequencies of sound waves were recorded to determine the wavelengths. These wavelengths are compared with the measured FL lengths and a constant deviation was observed, which gives the effective length of the TA Core as 55 cm. This effective length is used in the calculation of the FL ratio. The peak pressure in the TA cores and the onset Temperature Difference (TD) of the TAE with various FL ratios were compared. A normalized intensity of the sound wave produced by the TAE was also compared for different FL ratios. The optimum FL ratio was found to be 3.37. Figs 6, Refs 11.