Experimental Investigation of Windage Loss and Steady-State Temperature in Flywheel Energy Storage Systems

(The Flywheel Energy Storage System (FESS) has become an essential solution for grid frequency regulation due to its fast response, high power output, and low cost. FESS often employs a vacuum environment to reduce windage loss on the flywheel surface, but the absence of a heat transfer medium poses challenges for heat dissipation. Therefore, understanding the relationship between vacuum level and windage loss, as well as implementing effective thermal management strategies, is crucial. In this study, a scaled-down test rig for the generator energy storage flywheel was designed and constructed to measure the windage loss and steady-state temperature of the flywheel surface under various vacuum levels. The experimental results indicate that increasing the vacuum level to 95% reduces the windage loss by approximately 82%. Furthermore, a steady-state temperature calculation model for the flywheel was developed, with a deviation of less than 10% compared to simulation results. The model's accuracy was further validated through experimental testing. Additionally, three methods for monitoring the flywheel's surface temperature inside the vacuum chamber were compared. The infrared thermal imager demonstrated significant advantages in operational convenience and data comprehensiveness. These findings provide valuable insights for experimental research on FESS windage loss and thermal state monitoring in management systems.