Sensitivity analysis of the performance of a linear alternator at mechanical resonance under thermoacoustic power conversion conditions

Abstract

A linear alternator lie at the interface between the acoustic power generated by a thermoacoustic engine and an electric load, and thus, its performance is significantly controlled by its matching with the thermoacoustic engine and with the electric load. Under thermoacoustic power conversion conditions, small unavoidable changes in the operating conditions may incur significant effects on the alternator performance. In this work, the sensitivities of several alternator performance indices, namely, the acoustic-to-electric conversion efficiency, the mechanical stroke, and some of the main alternator losses (mechanical damping loss, seal loss, and electric copper loss), are examined to small changes in four operating conditions. Using the methodologies of the design of experiments and sensitivity analysis, a scheme of experiments is designed and carried-out to analyze the sensitivity of these indices to ± 10% changes in operating conditions at mechanical resonance. The operating conditions considered are the gas mixture composition, the mean gas pressure, the dynamic pressure ratio acting on the alternator and the electric load. The results reveal how variations in each of these operating variables as well as variations in their combined interactions affect the alternator’s performance with respect to the results obtained in a reference experiment.