MODAL AND AEROELASTIC ANALYSIS OF A MISTUNED COMPRESSOR BLISK USING AN EQUIVALENT BLISK MODEL

Aero-engine compressor rotors manufactured as blisk exhibit only little mechanical damping. Therefore, in the case of forced vibrations in combination with mistuning, the blade amplitudes may considerably exceed the tuned response. The following work presents the results of the simulation of the aeroelastic behaviour of the 6th integral rotor stage of the engine 3E's high pressure compressor. With the information of the blade frequencies an aeroelastic computation, using commercial CFD, is carried out in order to obtain the aerodynamic influence coefficients along with the aeroelastic eigenvalues. Subsequently an advanced lumped mass model is adapted to the mechanical properties of the compressor blisk and intensive numerical analyses of the forced response behaviour of the blisk are performed. Two different methods using the aerodynamic influence coefficients and equivalent aerodynamic mass-, damping-and stiffness-elements derived from the aeroelastic eigenvalues are employed to integrate aerodynamic forces in the model. Both methods are compared one another as well as validated against the results of bidirectionally coupled fluid-structure interaction simulations of forced response vibrations in a commercial CFD environment.