Dynamic Characteristics And Dynamic Balance Of APU Cantilever Rotor With High Speed

The Auxiliary Power Unit(APU)is a small Turboshaft Engine,many of which adopt cantilever rotor with high working speed,and the rotor design is rather difficult.The study of dynamic characteristics and dynamic balance of high-speed cantilever APU rotor can provide the basis for the design of rotor and verify its validity.Moreover,by means of enhancing the stability and repeatability of the dynamic balance of the cantilever rotor,the problem that the vibration of the APU caused by the rotor imbalance during the test can be well solved.In this paper,the cantilever rotor of an APU was taken as the object of study.The finite element modeling and dynamic characteristics of the APU rotor were calculated by use of the Samcef Rotor software,and the critical speed,mode and unbalance response of the rotor were obtained.The calculation results of unbalanced response were then used to determine the rotor dynamic balance correction plane;the influence of different components on rotor imbalance response was analyzed;the influence of various fulcrum spans on the dynamic characteristics of the cantilever rotor was analyzed after establishing their finite element models.The accuracy of the model was verified by the rotor dynamic characteristic test.Through the dynamic balance test of the cantilever rotor,the reason of the instability of the conventional dynamic balance test and the influence of the rotor disassembly on the remaining unbalance was analysed.The whole dynamic balancing scheme of gas drive was proposed,which boosted the stability of dynamic balance and was verified in the integral machine test.It provides a feasible dynamic balancing plan for similar cantilever rotors.