Fluid-Structure Interaction of Gas Turbine Blades
(Dhopade, Neely, Young)
The effects of low-cycle fatigue and high-cycle fatigue interaction on the aerodynamic and structural behaviour of a fan blade have been investigated. A numerically based analysis through the interfacing of computational fluid dynamics (CFD) and finite element modelling (FEM) analysis, referred to as fluid-structure interaction (FSI) was performed. Initial steady-state and transient results from an ongoing study on numerical simulations of two-way FSI to predict representative fluctuating loads on the fan rotor blades of the first axial compressor stage of a representative gas turbine engine were reported (Dhopade et al. 2010). The stator blade was modelled upstream of the rotor blades to simulate the turbulent shedding of wakes that result in aerodynamically induced vibrations of the rotor blades, a leading cause of high-cycle fatigue. The rotor blades are also subject to low-cycle fatigue induced by both the high rotational loads and the mean aerodynamic pressure loading experienced by the blades at various operating conditions. The results demonstrate that the presence of the upstream stator results in aerodynamic loads on the rotor blades that fluctuate by approximately 30% when compared to the case where the upstream stator is absent and the aerodynamic load is constant with respect to time. This implies that the presence of the upstream stator must be included in the FSI numerical model to fully predict the complex interaction.