某燃机电厂汽轮机汽缸-螺柱系统的多场耦合有限元应力分析

FEM-based Multi-field Coupling Stress Analyses of the Cylinder-bolts System in a Gas Turbine Power Plant

针对某燃机电厂的技术改造需要,以汽缸-螺柱系统为研究对象,应用弹塑性有限元方法,通过引入子-母模型映射关系,并考虑紧固螺柱-螺母、汽缸法兰、螺纹牙之间的非线性接触对,建立了汽缸体-紧固螺柱系统的三维有限元模型。分别对汽机技术改造前后两种热力参数(蒸汽温度、蒸汽压力)下的缸体及其紧固螺柱进行了温度应力、蒸汽压力多场耦合应力计算,获得了汽缸体及其紧固螺柱的整体与局域应力分布。结果表明,汽机改造后由于主蒸汽温度提高,会在不同程度上改变中分面各位置螺柱(螺钉)的最大应力,但其变化均在±5%范围内。据此,初步评估了汽机技改后汽缸及其紧固螺柱的服役安全性。

In accordance with the technical improvement of a gas turbine power plant,this article focuses on the cylinderbolts system. Based on the elastic-plastic finite element method,the sub-master model mapping relationship and the nonlinear contact pairs,a three dimensional finite element model of the cylinder-blots system is developed. The multi-field coupling stresses of both cylinder body and fastening bolts under two thermal mechanical parameters（ steam temperature and steam pressure） before and after the technical improvement of the gas turbine were calculated and the distributions of the overall stress in the cylinder body as well as the local stress in the fastening bolts were obtained. The results show that,although the maximum stress of the fastening bolts in different positions in the casing split will be changed in different degrees due to the increase of the steam temperature,their variations are in less than ± 5%. According to the stress analysis results,the service safety of both cylinder body and fastening bolts after the technical improvement of the gas turbine is evaluated preliminarily.