Study of Coupled vibration characteristics of coaxial feed pump-steam turbine shafting

In order to study the influence of the main engine feed pump integrated into the turbine-generator set shaft system on the turbine shaft vibration, a $\mathbf{6 6 0 M W}$ turbine-generator set of a power plant was taken as the research object. The Advanced Rotating Machine Dynamics Analysis software (ARMD) was used to model and calculate the eight support bearings, analyze the bending vibration characteristics of the steam engine shafting, and obtain the calculation results of modal mode shape and shafting unbalance response at each critical speed. The torsional vibration characteristics of the shafting system were analyzed, and the torsional vibration frequency, torsional vibration response calculation results, and journal strength check results were obtained. The research results show that the critical speed of the turbine rotor avoids the range of $-15\% \sim+15\%$ of the working speed, the unbalanced response of each shaft diameter at the working speed is less than $50 \mu \mathrm{~m}$, and the logarithmic attenuation rate corresponding to each vortex speed is greater than 0.1 at 3000 rpm. The torsional vibration frequency of the steam engine shafting system avoids the range of $\mathbf{4 5 \sim 5 5 H z}$ and $\mathbf{9 0} \sim 110 \mathrm{~Hz}$, which meets the requirements of rotor strength in the event of short circuit and misparallel. With the addition of friction couplings, the strength of the Vorcon rotor meets the design requirements under various short circuit and mis-parallel conditions.