基于响应面法的汽轮机转子等效应力分析

Equivalent Stress Analysis of Steam Turbine Rotor Based on Response Surface Method

为分析汽轮机转子材料制备、加工、安装和运行过程中结构尺寸、材料物性参数、温度等随机变量对其等效应力的影响,以某300MW级汽轮机高压转子为例,采用有限元方法计算得到了冷态启动过程中最大等效应力出现的时刻和部位,并且结合变量随机性,分别采用多项式响应面法和支持向量回归(SVR)响应面法拟合转子最大等效应力与随机变量之间的关系,比较分析了其拟合效果.同时,采用蒙特卡洛模拟法探究了在冷态启动过程中转子强度的可靠性和各随机变量的敏感性,得到了转子半径等6个随机变量的敏感性指数排列顺序.结果表明:SVR响应面法拟合效果比多项式响应面法拟合效果更好,2种响应面法得出冷态启动曲线的强度可靠性分别为96.99%和94.16%;在6个随机变量中,对汽轮机转子等效应力影响最大的是转子材料的弹性模量.

To investigate the influence of random variables,such as structural dimensions,material property parameters,and temperatures,on the equivalent stress of steam turbine rotor during material preparation,processing,installation and operation,taking the high pressure rotor in a 300 MW class steam turbine as the research object,the time and location of the maximum equivalent stress during cold start-up was obtained by calculating with finite element method.Meanwhile,combined with the randomness of variables,the relationship between the rotor maximum equivalent stress and the random variables was fitted with both of polynomial response surface method and support vector regression(SVR)response surface method,and analyses and comparisons were conducted on the fitting effects of above two methods.Additionally,the reliability of rotor equivalent stress and the sensitivity of various random variables during cold start-up process were investigated by Monte Carlo simulation method,while the sensitivity index order of six random variables including rotor radius,was determined.Results reveal that the fitting effect of SVR response surface method is better than that of polynomial response surface method,and the strength reliability indexes of above two response surface methods for the cold start-up curves are 96.99%and 94.16%,respectively.Among the six random variables,the elastic modulus of rotor material is identified as having the most significant impact on the equivalent stress of steam turbine rotor.