Influence of blade tip clearance on blade aerodynamic damping in transonic compressor

Based on transonic compressor flutter test rotor, an efficient aerodynamic damping computational model using phased lagged boundary conditions is established to analyze the influence of blade tip clearance on compressor flow field and aerodynamic damping. Numerical results of rotor aerodynamic performance, blade mode and flutter boundary analysis with design tip clearance are closely consistent with the experimental results. The rotor aerodynamic performances with different tip clearances (1.6%, 3.2% and 5.0% tip chord) show that tip flows can significantly reduce the total pressure ratio and efficiency of rotor. Unsteady pressure results on blade surface indicate that the unsteady flow response is a strong three-dimensional nature. Inter-blade phase angle (IBPA) and tip clearance are crucial factors influencing blade surface unsteady pressure. The first harmonic pressure amplitude in blade tip region which is associated with blade vibration relatively weakens due to the enhancement of blade tip flow with the increase of blade tip clearance. The stability of pressure surface tends to worsen due to increasing blade tip clearance. However, the influence of blade tip clearance on suction surface depends on inter-blade phase angle. The influence of blade tip clearance on blade aerodynamic damping has significant differences at different inter-blade phase angle, even an inverse relationship. Specifically, the aerodynamic damping is enhanced with increasing blade tip clearance at the least stable inter-blade phase angle.