摘要
为了对汽轮机启动过程进行优化,发展了一种转子热应力半解析递推计算模型。该模型考虑蒸汽换热系数的变化,将启动过程分解为多个换热系数不变的升温过程,各升温过程的换热系数值取为该升温过程开始时刻的换热系数。同时,将每个升温过程结束时刻转子的温度场拟合为只含偶数次幂的4次多项式,并将拟合的温度场作为下个升温过程的初始温度场,通过拉普拉斯变换法,计算出下个升温过程的瞬态温度场。利用半解析递推模型构造转子启动优化的目标函数,采用遗传算法对660 MW机组的冷态启动曲线进行了优化,优化后转子的最大热应力减小了19.4%,且启动时间减小了4.9%。为验证该半解析递推模型的计算精度和效率,分别采用有限元模型和半解析递推模型计算了660MW机组转子冷态启动过程中的瞬态温度场、应力场,计算结果表明:两种模型计算的转子关键部位热应力变化趋势相同,最大热应力相差0.11%,而递推模型计算的时间约为有限元模型计算时间的2.8%。
To optimize the start up process of steam turbine,a semi analytical recursive calculation model of rotor temperature field is developed.Considering the change of heat transfer coefficient with time,the start up process is divided into multiple heating processes with constant heat transfer coefficient in the algorithm.The value of heat transfer coefficient of each heating process is taken as the initial value of heat transfer coefficient at the beginning of the process.The temperature field at the end of each process is fitted as4th order polynomial,and the4th order polynomial will be the initial temperature field of the next temperature rising process.Then,the transient temperature field of the next temperature rising process is calculated through the Laplace transform method.To verify the accuracy and efficiency of the semi analytical recursive model,finite element method and recursive model are used to calculate the temperature field and stress field of the rotor during cold start of a660MW turbine unit.The calculation results show that the trend of the thermal stress calculated by two models is the same.The thermal stress calculated by two models differs by011%,and the computation time of the recursive model is about28%of the finite element model.An objective function of rotor start up optimization is constructed by the semi analytical recursive model,and the genetic algorithm is used to optimize the rotor cold start up of a660MW unit.After optimization,the maximum thermal stress of the rotor is reduced by194%and the starting time is reduced by49%.
作者
李猛
郭勇
马骏
高进
徐自力
LI Meng;GUO Yong;MA Jun;GAO Jin;XU Zili(State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi’an Jiaotong University,Xi’an 710049, China;Shanghai Aerospace Precision Machinery Research Institute, Shanghai 210699, China;Dong Fang Turbine Co. Ltd., Deyang, Sichuan 618000, China)
出处
《西安交通大学学报》
EI
CAS
CSCD
北大核心
2018年第1期54-60,共7页
Journal of Xi'an Jiaotong University
基金
国家自然科学基金资助项目(51675406)
关键词
转子
热应力
启动优化
遗传算法
rotor
thermal stress
start up optimization
genetic algorithm
