超超临界汽轮机低压缸有限元分析模型的研究

Study of the FEA Models of Ultra-supercritical Turbine LP

低压汽缸局部热应力是超(超)临界汽轮机安全可靠性评价的基础指标,有限元分析是计算汽缸热应力的基本方法。低压汽缸结构复杂,可视为板、壳、杆和体等结构的组合体,选择合理的单元结构是有限元计算结果可靠性的重要保证。采用MSC Nastran有限元软件,在简化的汽缸模型上,比较研究了不同单元结构计算结果的差异。其次,分别使用体单元和壳单元建立了超临界600MW空冷汽轮机低压内缸简化的有限元分析模型,通过热应力计算结果的比较,指出了壳单元的技术优势。

Local thermal stress on LP casing is one of the key parameters to evaluate availability and safety of super critical steam turbine. Finite element analysis is a basic method for it. Complex LP casing may be composed of shell ,plate ,bar and solids etc. Adequate element type is key to obtain reliable FEA results. In present paper, MSC Nastran software is taken to to compare element influence on a conceptual turbine casing. A sample LP turbine casing of 600MW air -cooling turbine is also analyzed with 3D tetrahedral and With shell -plate elements thermal stress distribution ,respectively. It is indicated By the results that calculation model consist of shell elements works better than models consist of other types of element.