Flutter analysis of turbomachinery based on phase lagged boundary condition

Based on phased lagged boundary conditions, an efficient aerodynamic damping computational model of a transonic compressor rotor with double passage was established. Numerical results of rotor aerodynamic performance, flutter boundary and blade modal analysis were consistent closely with experimental results respectively. The aerodynamic damping results of rotor with different interblade phase angles (IBPA) and first bending mode were calculated using double passage method and conventional multiple passage energy method. The numerical results indicated that the aerodynamic damping attained by double passage method and conventional multiple passage energy method agreed with each other. The efficiency was improved by almost 7.7 times than conventional multiple passage energy method and the memory requirement was about 0.45 times to the conventional method. The aerodynamic damping results for different vibration amplitudes demonstrates that the nonlinear fluid dynamics effects are significant at such a small geometric displacement. Compared with the damping at design point, aerodynamic damping of rotor is reduced at near flutter operation condition, while the minimum aerodynamic damping is gotten at the same interblade phase angle (-42.4 degree).The results show that IBPA has significant influence on the flutter of rotor blades.