Abstract
The rotordynamics and harmonic characteristics of the rotor assembly designed for 40-kW high-speed sCO2 direct-coupled turbo-generator pair have been evaluated numerically using finite element solver “ANSYS Mechanical”. First, the shaft geometry and dimensions have been optimized using lumped mass-inertia-based AxSTREAM RotorDynamics module followed by the bearing selection analysis using SKF SimPro expert to ensure enough separation margin from the nearby critical speeds. Equivalent 2D geometry has been used with an FEA-based ANSYS general axisymmetric model to reduce the computation time. The effect of the damping on the forces transmitting to the bearings and shaft deflection at the critical speeds are analyzed by performing harmonic analysis under various damped and undamped conditions (ζ = 0, 0.005, 0.01, and 0.02).
