Experimental and theoretical investigation on casing vibration for dual-rotor-support-casing system with rotor-casing rub

This study investigates the dynamic behavior of dual-rotor-support-casing (DRSC) gas turbine systems subjected to rotor-stator friction, aiming to enhance diagnostic methods for rotor-stator rubbing issues. A comprehensive finite element model of the DRSC system is developed, incorporating shear distortions, inertia effects, and gyroscopic forces of both rotors and casing, alongside a rotor-casing interaction model that accounts for their relative movements. Both numerical simulations and experimental analyses are conducted to examine the acceleration responses during rotor-casing contact, with particular attention to variables such as rotational speed ratios, initial clearances, and friction stiffness. The dynamic behaviors are evaluated using time-based acceleration waveforms, frequency spectra, and waterfall diagrams. The results demonstrate that rotor-stator rubbing induces distinct impact patterns in the frequency spectra of casing vibration acceleration signals and that the severity of friction is significantly influenced by the initial clearance and contact stiffness. These findings provide valuable insights into the dynamic interactions within DRSC systems, contributing to more effective diagnostics and mitigation strategies for rotor-stator rubbing in gas turbines and advancing the understanding of DRSC system dynamics.