Aeroelastic Response of Bird-Damaged Fan Blades Using a Coupled CFD/CSD Framework

The aeroelastic response of a bird-damaged fan stage at the inlet of a high-bypass ratio turbofan engine is examined using a combined CFD/CSD model. ANSYS CFX is used for the computational fluid dynamic (CFD) calculations combined with the ANSYS Multifield (MFX) solver that couples ANSYS CFX with ANSYS Mechanical APDL to perform aeroelastic response calculations. The damaged fan sector consists of 5 blades that represent the geometry resulting from a numerical bird strike simulation. The forced response of the undamaged blades downstream of the damaged sector exhibits the highest level of structural response. The structural response of these undamaged blades is dominated by the first bending mode and increases in amplitude with time. The aeroelastic response shows a similar behavior, with the downstream undamaged blades exhibiting a growing structural response that is dominated by the first bending mode. The aeroelastic response of the damaged blades also contains contributions from the second torsion mode. An examination of the work exerted by the aerodynamic forces suggests that the growth in blade response for the upstream damaged blade is due to an aeroelastic behavior that may be indicative of a potential instability.