Study on the Impact of Cooling Air Parameter Changes on the Thermal Fatigue Life of Film Cooling Turbine Blades

Film cooling has been increasingly applied in turbine blade cooling design due to its excellent cooling performance. Although film-cooled blades demonstrate superior cooling effectiveness, the perforation design on blade surfaces compromises structural integrity, making fatigue failure prone to occur at cooling holes. Previous studies by domestic and international scholars have extensively investigated factors influencing film cooling effectiveness, including blowing ratio and hole geometry configurations. However, most research has overlooked the investigation of fatigue life in film-cooled blades. This paper systematically investigates blade fatigue life under various cooling air parameters by analyzing the relationships among cooling effectiveness, stress distribution, and fatigue life. Results indicate that maximum stress concentrations occur at cooling hole locations and near the blade root at trailing edge regions. While cooling holes effectively reduce blade surface temperature, they simultaneously create stress concentration zones around the apertures. Both excessive and insufficient cooling air pressure and temperature reduce thermal fatigue life, with optimal parameters identified as 600 K cooling temperature and 0.75 MPa pressure, achieving a maximum thermal fatigue life of 3400 cycles for this blade configuration. A thermal shock test platform was established to conduct fatigue experiments under selected cooling conditions. Initial fatigue damage traces emerged at cooling holes after 1000 cycles, with progressive damage expansion observed. By 3000 cycles, cooling holes near blade tip regions exhibited the most severe failure, demonstrating near-complete functional degradation. These findings provide critical references for cooling parameter selection in practical aeroengine applications of film-cooled blades.