Four-stage loop-type cascade traveling-wave thermoacoustic engine

•A loop type cascade traveling wave thermoacoustic engine with four regenerators is demonstrated.•Enlarged regenerators and incrementally enlarged duct diameters were used.•The prototype engine has a high acoustic impedance at regenerators, and traveling wave field in ducts.•This engine enables acoustic power amplification by a factor of the number of regenerators.

We designed and built a prototype of a loop-type cascade traveling-wave thermoacoustic engine with four regenerators. The objective with this prototype engine was to achieve both high acoustic impedance at the regenerator position and a traveling-wave field in ducts, and to amplify the acoustic power by a factor equal to the number of regenerators. To achieve this objective, we enlarged the regenerator cross-sectional area and incremented the duct diameter. We measured and analyzed the acoustic field and verified that its characteristics met the objectives.