水轮机叶片激光增材再制造的温度场与应力场仿真研究

Simulation Study of Temperature Field and Stress Field in Laser Additive Remanufacturing of Hydraulic Turbine Blade

水轮机转轮及叶片为水轮机的核心构件,但在水轮机长时间运转过程中易出现不同程度的空蚀现象。激光增材再制造技术由于具有效率高、热输入低、结合性能好等特点,可作为该类缺陷的有效修复手段。建立水轮机叶片激光增材再制造三维有限元模型,计算激光增材再制造区域温度场和应力场的瞬态分布规律。结果表明,激光增材再制造过程对水轮机叶片的温度、应力和应变影响主要集中在增材再制造区域附近。单道激光增材再制造热影响范围约为10 mm,四道激光增材再制造热影响范围上升至25 mm。此过程所产生的变形极小,在完成四道激光增材再制造后,中心横截面所产生的最大变形为0.15 mm,对水轮机叶片整体影响不大。

Hydraulic turbine runners and blades are the core components of the Hydraulic turbine,but they are prone to cavitation in varying degrees during long-term operation.Laser additive remanufacturing can be used as an effective repair method for such defects due to its high efficiency,low heat input and good bonding performance.In this paper,a three-dimensional finite element model for laser additive remanufacturing of hydraulic turbine blades is developed,and the transient distribution laws of temperature field and stress field in the laser additive remanufacturing area are calculated.The results show that the influence of laser additive remanufacturing process on the instantaneous temperature and stress of hydraulic turbine blades is mainly concentrated near the additive remanufacturing area.The heat affected range of single laser additive remanufacturing is about 10 mm,and the heat affected range of four laser additive remanufacturing increases to 25 mm.The deformation generated in this process is very slight.The maximum deformation generated by the central cross section is 0.15 mm when the four-channel laser additive remanufacturing is completed,which has little effect on the overall turbine blade.