Influences of unbalance phase combination on the dynamic characteristics for a turboprop engine

Abstract To reduce excessive vibration of a turboprop engine with qualified balanced compressor and turbine rotor, the finite element model of the rotor system was established. The magnitude, axial distribution and especially the phase combinations of the residual unbalances were considered and optimized. Based on the numerical results, the whole engine tests were conducted for verification. The numerical and experimental results show that the vibration level of the rotor system can be significantly reduced by only changing the phase combination of the residual unbalances. The magnitude, axial distribution of residual unbalance and rotational speed of the rotor play a very important role in determining the optimal phase combination. The optimal phase combination under different rotational speeds might be conflicting, and reasonably designed optimization would be a feasible solution. The findings of the research can provide important reference for the design and troubleshooting for similar industrial turbine engines.