动叶水蚀疲劳寿命分析模型的研究

为了提高汽轮机湿蒸汽级叶片的可靠性，预防电厂中汽轮机叶片的水蚀疲劳断裂，基于动叶通道中水滴运动、撞击叶片表面速度分布以及液固撞击等效应力，采用合适的疲劳始裂寿命计算公式和非线性疲劳累计损伤准则，建立了叶片水蚀疲劳寿命分析模型。详细分析了某汽轮机湿蒸汽级动叶片的水蚀疲劳特性，获得了其水蚀疲劳的门槛速度，这一速度与实验数据吻合较好，同时获得了该动叶片在不同汽轮机运行工况下水蚀疲劳的状况，疲劳初始裂纹发生的部位和时间。文中建立的叶片水蚀疲劳寿命分析模型可以定量地计算水蚀疲劳寿命，为分析、预防水蚀提供了有力的工具。

NUMERICAL MODEL FOR BLADE FATIGUE LIFE OF LIQUID CORROSION IN STEAM TURBINE

In order to improve reliability of wet steam blade in steam turbine and prevent blade failure from liquid corrosion, based on the knowledge of liquid droplet motion in blade channel, the velocity and equivalent stress of liquid droplet impacting surface of blade, suitable equation to evaluate the fatigue life of crack initiation and nonlinear cumulative damage rule are adopted to develop numerical model liquid corrosion fatigue life of blade. At last, the liquid corrosion fatigue life of a wet steam blade in a steam turbine is analyzed, and the threshold speed of the blade material is obtained, it shows preferable agreement with measure data, then more results such as liquid corrosion status of the blade under different loads, the crack position and crack initiation time of blade are obtained. It is shown that the analysis model of liquid corrosion fatigue life for blade can give some quantitative results and it may be helpful to evaluate liquid corrosion fatigue life and prevent blade from liquid corrosion.