Abstract
The purpose of the study is to investigate high-speed turbomachinery system stability. Unstabilizing force due to Thomas force induced by turbine reduces a system damping at critical speed. In this paper, high-speed turbomachinery system is modeled using FEM, and natural frequency and damping ratio are calculated by a complex eigenvalue analysis, using the double QR method. In order to estimate the unstabilizing force, first torque generated by turbine blades is calculated by CFD, then cross coupling stiffness is calculated by the torque. As the calculation results, the system damping is reduced by cross coupling stiffness from complex eigenvalue analysis results.
