大功率汽轮机高温叶片蠕变特性数值研究

Numerical Study on Creep Properties of the High Temperature Blade for Large Capacity Steam Turbines

近年来汽轮机朝着大功率、高参数方向快速发展,汽轮机进口蒸汽温度不断提高,导致叶片的工作环境进一步恶化。叶片作为汽轮机的核心部件,其安全性直接影响汽轮机机组的运行状况,因此研究高温条件下叶片的强度和蠕变特性非常重要。以某大功率汽轮机高温叶片为例,构造了叶片和叶轮三维有限元模型,采用商用有限元软件ANSYS分析了离心力和温度场共同作用下的叶片热弹性应力及变形;然后,应用诺顿模型分析了该叶片经历100 000 h蠕变历程的应力和应变。建立了完整的汽轮机叶片蠕变特性分析数值模型,研究工作为汽轮机叶片的静强度和蠕变特性研究提供了具体的方法,所得结论对于高温叶片设计具有指导意义。

With the development of large capacity and high parameter steam turbine and the increase of inlet steam temperature, the working conditions of turbine blades get worse. As the blade is one of the critical components in steam turbine, its security of turboset is directly affected by the reliability of blade. Hence, it is very important to study the blade strength and creep properties. The basic theories and the analysis methods of creep were introduced. Taking a high temperature blade of a large capacity steam turbine as example, the three-dimensional finite element model of the blade was built. The thermal elasticity stress and displacement of the blade were analyzed considering centrifugal force and temperature load by the finite element analysis software ANSYS. Then the Norton model was adopted to simulate the blade creep of 100 000 hours and the stress and strain of the blade were obtained. A complete numerical analysis method was developed and the specific method was provided for steam turbine static strength and creep. The conclusions can give some advice to blade design.