Dynamic similarity design of an aero-engine rotor system was presented to study its dynamic characteristics using the design model instead of the real structural system. Firstly

the similar equivalent model of the rotor full scale prototype

based on the dynamic equivalence principle of the rotor system

was established by dynamic optimization. Then

the dynamic similarity criterions of the rotor system were derived by equation analysis combined with dimensional analysis

and the reduced-scale model of the similar equivalent model was constructed according to the similarity relations of the rotor design parameters. Finally

using the model updating method

the dynamic similarity model of high prediction accuracy was obtained by updating the similarity error of the three-dimensional design model. Taking the dynamic similarity design for the low-pressure rotor of the dual-rotor aero-engine as an example

the effectiveness of the dynamic similarity design method was validated by finite element simulation. Results showed that the dynamic similarity model obtained by this method could effectively predict the critical speeds and unbalance responses of the full scale prototype within the design operation speed. The similarity errors for the first three critical speeds were 3.09%

1.75% and 0.31%

respectively

and the corresponding modal assurance criterion values were all above 0.93. This method has great value for practical application

and provides a reference for dynamic similarity design of the whole aero-engine.