Gyroscopic effect evaluation and resonance speed prediction of complex high-speed rotor system based on energy

Abstract

Making full use of gyro effect to adjust resonance speed distribution is of great significance for avoiding resonance design of high-speed rotor system. Existing rotor dynamics research often regards gyro effect term as an implicit quantity to be solved in dynamic equation of complex rotors, but does not carry out quantitative evaluation on its gyroscopic effect. Therefore, this paper decomposes kinetic energy components of the rotor, deduces equilibrium relationship between modal kinetic energy and potential energy of the rotor system at a specific speed, defines the ratios of gyro kinetic energy to lateral vibration energy/elastic potential energy in modal vibration as parameters to evaluate the degree to which the gyro effect affects resonance characteristics. Based on this, the gyro effect of a typical complex high-speed rotor system is evaluated. The derivation process also shows that, modal shape directly determines the gyro energy ratios, ultimately determines the change amplitude of resonance speed. Then a method to predict resonance speed under gyro effect based on modal shape is proposed, and experimental verification is carried out. The results show that, it is feasible and concrete to understand gyroscopic effect from the perspective of system energy equilibrium and transformation.