Vibration suppression design for a turboshaft engine with shared bearing cavity structure

Abstract To develop advanced civil turboshaft engine with long life and high reliability, research on vibration suppression technology was conducted for a turboshaft engine with shared bearing cavity structure. The nonlinear dynamic model of the dual-rotor system with shared bearing cavity was established with nonlinear forces of the supports considered. The presence of vibration coupling in the dual-rotor system with shared bearing cavity structure was found, which would increase the resonance opportunities of the rotor system and might lead to disastrous accidents. The mechanism of coupled vibration was revealed. Then an optimization algorithm was developed to optimize the shared bearing cavity structure. Thus the vibration of the whole engine can be reduced and isolated. After implementing the optimization measures, over 15,000 h bench test and flight tests were conducted successfully. The experimental results demonstrated that the engine’s overall vibration reduction design was reasonable, with vibration levels effectively controlled. During long-duration, multi-condition, and full-speed-range operations, the steady-state vibration amplitudes remained below 12 mm/s, exhibiting stable vibration characteristics and significantly lower than the design requirements for turboshaft engines.