Experimental and Theoretical Temperature Gradient Coefficient in Thermoacoustics

The temperature gradient coefficient of a cotton wool stack is investigated at a nonzero temperature gradient. The direct measurement method of the temperature gradient coefficient is proposed and its experimental results are compared with theoretical calculations. Parallel, capillary-tube-based thermoacoustic theory for random porous media is applied for theoretical calculations. Comparison results show reasonable agreement in the temperature gradient coefficient, which is useful to determine the performance of thermoacoustic devices. These results lead to convincing the validation scheme of both the measurement methods and theoretical calculations.