Research on mode dynamic balancing method of dual-rotor aero-engine

In view of the dual-rotor system with two sets of vibration modes of low-pressure rotor excitation and high-pressure rotor excitation, the orthogonality of the two vibration modes was affected by the speed ratio, so N1+N2 plane and N1+N2+4 plane mode dynamic balance method of the dual-rotor system was proposed by replacing the rotor mode under the actual operating speed line with the rotor mode under the constant speed ratio. On the basis of the known modal orthogonality theory of the dual-rotor system, the equilibrium conditions of the two-rotor system N1+N2 and N1+N2+4 plane mode dynamic balance methods were deduced, and two dynamic balance methods of the calculation equations of the unbalanced mass and the orthogonal correction mass group were given. What’s more, taking a certain type of aeroengine dual-rotor system as an example, the process of balancing each order mode was given by the N1+N2 mode dynamic balancing method. Finally, the dynamic balance verification experiment was carried out on the dual-rotor test system. The experimental study found that the vibration reduction effect of dynamic balance method can reach up to 72.4% under the condition of constant speed ratio; when the high and low pressure rotor speed control rate was the actual working speed line in the working speed range, the total vibration amplitude at each critical speed was reduced to below 120 µm, meeting the design requirements. The experimental results showed that the proposed mode dynamic balancing method for the dual-rotor aeroengine is feasible. © 2023 BUAA Press. All rights reserved.