The existence of a recast layer of film cooling holes on turbine blades imposes a crucial problem that affects the quality of fast electrical discharge machining (EDM) drilling. This paper focuses on an evolution process from molten material generation to recast layer formation. Single pulse discharge observation experiments with a high speed camera and a self-built observation platform were carried out to observe the formation and movement of the molten material. A novel thermal-fluid coupling model is proposed to combine fast EDM drilling methods with special materials and geometric properties of film cooling hole machining. A heat transfer module, a turbulent flow computational fluid dynamics module, a phase change module and a level set method are combined in this model. The complete process of generation, flow and solidification of molten materials is investigated by simulation with a single pulse discharging. The simulation results agree well with the experimental observation results. A thermal-mechanical coupling analysis of a molten material evolution process is carried out based on the temperature, velocity and pressure fields from the thermal-fluid model. Simulation results show that the molten material is generated at 1 μs after the starting of a discharge, and solidifies within 20 μs after the ending of the discharge. Under the influence of a high-speed flushing fluid, molten materials will not splash into a gap channel along the radial directions. Most of the molten material enters the gap channel along the workpiece surface with a velocity of over 25 m s⁻¹. The moving direction of the molten material is consistent with that of a flushing fluid. The thickness of a recast layer gradually increases from bottom to top in the fast EDM drilling.

涡轮叶片上存在重铸薄膜冷却孔层是影响快速放电加工 (EDM) 钻孔质量的关键问题。本文重点介绍从熔融材料生成到重铸层形成的演变过程。使用高速相机和自建观察平台进行单脉冲放电观察实验，观察熔融材料的形成和运动。提出了一种新的热流体耦合模型，将快速电火花钻孔方法与薄膜冷却孔加工的特殊材料和几何特性相结合。该模型结合了传热模块、湍流计算流体动力学模块、相变模块和水平集方法。完整的生成过程，通过模拟单脉冲放电研究熔融材料的流动和凝固。模拟结果与实验观测结果吻合较好。基于来自热流体模型的温度、速度和压力场，对熔融材料演化过程进行热-机械耦合分析。仿真结果表明，熔融材料在 1μ的放电的开始之后s和在20凝固μ放电的结束之后第 在高速冲洗液的作用下，熔融材料不会沿径向飞溅到间隙通道中。大多数熔融材料沿着工件表面以超过25 ms ^-1的速度进入间隙通道。熔融材料的运动方向与冲洗液的运动方向一致。在快速电火花钻孔中，重铸层的厚度从下到上逐渐增加。