Abstract
Selected from various eigenmodes of blading, nodal diameter k= 0 and k= 1 are both related to shaft torsional and/or axial vibration and shaft bending vibrations respectively. In order to avoid the possibility of 2f (f=power system frequency) from torsional vibration resonance, ISO regulates the final calculation results considering the combination between k= 0 blade and torsional shaft vibration. Previous study has reported a global method for blade-shaft torsional coupled vibration analysis governing both k= 0 and k= 1 in a systematic manner, and torsional coupled vibration analysis was completed. However, it is also known that coupling of blade-shaft axial vibration also influences the resonance of blade-shaft system, and it is highly requested to estimate resonance frequency accurately. Thus, A method for blade-shaft coupled vibration analysis in consideration of axial vibration coupling is proposed and its feasibility is investigated. A scale model of steam turbine is targeted as an example and calculated resonance frequencies are compared with experimental data and FEM data. As a result, the new method in consideration of axial vibration coupling is feasible tool to calculate resonance frequencies more precisely than previous method. In addition, it is demonstrated that previous method is still effective when axial vibration is constraint
