汽轮机阻尼围带长叶片振动特性研究

为了获得阻尼围带叶片的振动特性,提高汽轮机阻尼叶片的设计水平,采用扭曲梁单元模型,推导了阻尼围带的刚度和阻尼矩阵,建立了阻尼围带长叶片振动分析模型,并且在分析阻尼围带叶片整圈节径振动时采用了波传递方法进行降阶,以提高计算效率.360mm阻尼围带叶片的分析结果与实验数据吻合良好.然后再详细分析了某阻尼围带末级长叶片的振动特性,获得了叶片的扭转恢复角、静频和动频以及节径振动的坎贝尔图,其中静频和动频与三维模型计算结果对比表明了发展出来模型计算结果的合理性.文中建立的模型也可以推广应用于具有其它阻尼器叶片的动力分析,作为阻尼叶片优化设计的基础,为阻尼叶片设计提供实用工具.

NUMERICAL MODEL FOR VIBRATION CHARACTERISTIC OF STEAM TURBINE BLADE WITH DAMPED SHROUD

In order to obtain vibration characteristic of damped blade, and improve its design technique, by using pretwist beam element and investigating the stiffness matrix and the damping matrix of damped shroud, numerical model for vibration characteristic of steam turbine blade with damped shroud has been developed. Meanwhile, Harmonic Wave Propagation Method is adopted to improve calculation efficiency. The comparison of calculation results with experimental data of a 360mm blade shows good agreement. Then the dynamic characteristic of a last stage long blade with damped shroud is analyzed in detail, some results as untwist angle, static and dynamic frequency and Campbell diagram of nodal diameter vibration are obtained, the comparison of static frequency and dynamic frequency with results from three dimensional model shows the numerical model can get a rational result. Dynamic characteristic of other dampers of blades can also be analyzed by the model, so it may be usable for damped blade design and be the base for optimization of damped blade.