Dual-directional ultrasonic vibration-assisted femtosecond laser drilling of film cooling holes

Film cooling technology is essential for ensuring the prolonged and stable operation of turbine blades in high-temperature environments in aircraft engines. This study systematically explored the use of ultrasonic vibration-assisted femtosecond laser composite processing technology for machining film cooling holes, conducting extensive research and innovation in this important field. The movement and evolution of debris under dual-directional ultrasonic vibration were investigated using a simulation model. A multi-parameter cooperative regulation mechanism was proposed to optimize the ultrasonic-assisted femtosecond laser drilling process. This approach significantly improved the machining quality and efficiency of film cooling holes in nickel-based superalloys. The study systematically investigated the effects of ultrasonic vibration direction and amplitude on hole depth, taper, and wall deposition at various drilling stages. The experimental results showed that the ultrasonic vibration-assisted technology increased the processing efficiency of blind holes and through-holes by approximately 12 % and 19 %, respectively. Notably, when machining inclined holes, the dual-directional ultrasonic vibration-assisted femtosecond laser technology demonstrated significantly greater improvements in both quality and efficiency. This technology reduced the percentage of oxygen atoms by 26.9 %, and the surface roughness (Ra) by 21 %, achieving a depth-to-diameter ratio of 6.6:1 and a surface roughness (Ra) of 3.2 μm, significantly improving the machining results. This study not only demonstrates the potential application of ultrasonic vibration-assisted femtosecond laser drilling technology in the machining of film cooling holes for aviation engines but also provides detailed process optimization and cooperative control strategies. These innovative results offer robust technical support for further enhancing the performance of aviation engines.