The reliability and durability of piston rings in double-acting Stirling engines are critical to overall engine performance. This study investigates the dynamic tribological behavior of the piston ring-cylinder liner contacts during operation. By establishing a coupled dynamic-tribological-leakage simulation model, the friction, sealing, and wear performance of the ring pack under rated and variable-speed operating conditions are systematically analyzed. Under the rated condition of 1800r/min, the instantaneous maximum friction forces of the top ring and the second ring are 392.3 N and 163.7 N, respectively, while the corresponding cycle-averaged friction forces are 147.9 N and 94.8 N. The instantaneous peak frictional power losses are 1360 W and 590 W, and the cycle-averaged frictional power losses are 470.2 W and 309.3 W, respectively. The peak total contact pressures reach 18.9 MPa for the top ring and 13.55 MPa for the second ring, and the maximum radial wear depths after 100 h of operation are 0.121 mm and 0.115 mm, respectively. When the rotational speed increases from 900r/min to 3600 r/min, the blow-by of the ring pack decreases by 68.8%, whereas the total frictional power loss and the wear rate increase by 229% and 122%, respectively. These results quantitatively reveal an inherent and previously unresolved trade-off between sealing performance and wear life for filled PTFE composite piston rings in double-acting Stirling engines. The proposed framework provides physically based design metrics for ring material selection, ring geometry optimization, and operating-condition assessment, and supports reliable sealing performance and service-life prediction for Stirling engine applications.
Lei et al. (2026) studied this question.