Computerized measurement of thermoacoustically generated temperature gradients

Abstract

The computerized measurement of thermoacoustically generated temperature gradients in short, thin plates is reported. The computerized data acquisition system is delineated. The temperature difference developed across a stack of short plates was measured as a function of the longitudinal position of the plates in a resonant tube for acoustic pressure amplitudes of 0.5 to 6.6 kPa, and static (or mean) pressures from 100 to 440 kPa, in argon and helium for the first through the third harmonic frequencies of the tube. Measured data were compared with predictions based on work done by Wheatley and others [J. Wheatley, et al., Journal of the Acoustical Society of America, v. 74, pp. 153-170, 1983] and results reported by Muzzerall (Master's Thesis in Engineering Acoustics, Naval Postgraduate School, Monterey, CA, September 1987). For low acoustic and static pressures, there is good agreement between measured data and theory. As the acoustic pressure amplitudes increase there is a general degradation of agreement up to the point at which it appears saturation of the thermoacoustic effect occurs.