Abstract
The co-cavity structure replaces the rear bearing cavity and bearing frame of the power turbine shafting. This modification not only reduces the weight of the entire system but also diminishes the axial size of the engine and improves its thrust-weight ratio. However, this innovative design introduces new technical challenges such as gas generator rotor vibration transmission and stiffness design of the co-cavity structure. To further explore the vibration characteristics of a turboshaft engine with this novel configuration, this paper employs the substructure method to develop a nonlinear numerical model of the entire system. It calculates the vibration response of the gas generator rotor and power turbine rotor under the co-cavity structure. Additionally, it discusses the impact of the co-cavity structure's support stiffness on the vibration characteristics. The efficacy of this proposed structure is validated through a full-scale power turbine experiment. The findings demonstrate that rational design of the co-cavity structure's support stiffness effectively mitigates transstatic coupling resonance.
