Determination of the stability limit of a thermoacoustic engine using the finite element method

Determination of the Stability Limit Using 2D FEM

In thermoacoustic engines, sound is generated by a temperature gradient across a porous stack. The threshold value at which oscillation spontaneously begins (the onset) is traditionally calculated using 1D tools such as DeltaEC. However, these tools neglect 2D effects at the interface with the heat exchangers. The authors solve the coupled acoustic and thermal equations using a 2D finite element model (FEM). By formulating the system as an eigenvalue problem, the stability limit is precisely determined at the point where the damping becomes zero. The model explains discrepancies between 1D theory and measurements.

• Authors: J.A. de Jong, Y.H. Wijnant, and A. de Boer (University of Twente)

• Publication: Proceedings of the International Conference on Acoustics (ICA 2013), pp. 1553–1556

• Location & Date: Montreal, Canada (June 2–7, 2013)

• Keywords: Thermoacoustics, stability limit (onset), finite element method (FEM), eigenvalue problem, DeltaEC, standing-wave motor

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