Electric power generation via thermoacoustic oscillations using the Wells turbine

Electric power generation is demonstrated experimentally using the Wells turbine connected coaxially to a DC generator and driven by self-excited thermoacoustic oscillations within an air-filled, looped tube. Two stacks subjected to an appropriate temperature gradient are placed at diametrically opposite positions in the tube. When the Wells turbine is positioned near a pressure node of the oscillations, it begins rotating spontaneously, though its motion fluctuates due to airflow comprising both the first and second acoustic modes of oscillations. To stabilize the turbine rotation, the second mode is selectively suppressed through the local connection of Helmholtz resonators near the position opposite the turbine. A maximum voltage of approximately 11 V is generated under no-load conditions, while a maximum power output of 2.1 W is attained at 6.5 V with a 20-Ω load. These results demonstrate that the Wells turbine, originally designed for low-frequency energy harvesting from oscillating water columns, can be effectively adapted for electricity generation via high-frequency thermoacoustic oscillations. [Work supported by JSPS KAKENHI Grant Nos 25K07574 and 18H01375.]