Performance comparison of thermoacoustic engines with constant-diameter resonant tube and tapered resonant tube

Two standing-wave thermoacoustic engines with a constant-diameter resonant tube and a tapered one, respectively, are simulated with linear thermoacoustics to explore the reasons for performance improvement of the thermoacoustic engine with the tapered resonant tube substituting for the constant-diameter one. Computed results indicate that the viscous loss in the tapered resonant tube is much lower than that in the constant-diameter one, and the smooth joint between the tapered resonant tube and its resonant cavity may avoid the acoustic power loss derived from sharp variation of flow area. The comparison between the computed results and the experimental data indicates that the simulation can roughly predict the performance of thermoacoustic engines with these two types of resonant tubes.