Numerical Simulations of Forced Response and Flutter in Compressor Rotors

摘要

Forced response and flutter are two major aeroelastic phenomena existed in compressor rotors. An aeroelastic analysis system (AEAS) written in standard FORTRAN language has been designed recently which allows forced response and flutter calculations for three-dimensional turbomachinery rotor blade models. In AEAS, the steady and unsteady aerodynamic forces required for aeroelastic calculations are obtained from the commercial CFD software FLUENT, and the structural dynamic computation is based on finite element method. The time-marching method is used in AEAS to get transient responses of displacements and dynamic stresses on rotor blades, thus to simulate forced response and flutter in compressor rotors. In forced response analysis, periodic unsteady pressure field are applied to rotor blades at possible resonances on Campbell diagram to compute amplitudes of dynamic stresses, then dangerous conditions of rotors are assessed. In flutter analysis, for a given working condition, the structural solver and the unsteady flow solver are invoked alternately, transient responses of blades are provided to determine whether flutter occurs, then all the operating points at which flutter getting started are connected in compressor characteristic map, forming flutter boundaries of compressor rotors. Numerical results showed good agreement with the experimental results, which indicates that it is possible to obtain more accuracy results using time-marching method with current computational resources in both forced response and flutter analyses.