The Response Prediction And Detection Of Unbalanced Vibration For The Dual-Rotor System Of Aero-engine

The rotor system is a key component of aero-engine and its dynamic characteristics affect the stability of the engine.At present,most of aero-engines are mainly composed by internal and external dual rotors with intermediate bearing support,which characteristics of long span,the relatively lower supporting stiffness and the elastic supports make it very sensitive to mass unbalance,easily resulting in the excessive vibration fault during the use of engine.Until now,the research on the vibration characteristics of the aero-engine rotors in the engineering field is mainly to collect the fault signal via multiple start-stops,but this method is time-consuming and costly.Therefore,it is of great theoretical significance and engineering value to analysis the global distribution of unbalanced vibration response of the dual-rotor system and build the estimation model of unbalance vibration response based on finite unbalanced conditions,and realize the unbalance location of complex dual-rotor system.In this paper,the dual-rotor system with four-disc and five-support was taken as the research object,and the unbalanced response of the system was analyzed and studied.The main works are as follows:Firstly,the unbalance parameters of a single unbalanced disc and the double unbalanced discs were sampled for a given space range based on Latin hypercube experimental design method,and then vibration amplitude ranges at the measuring points were obtained through the multi-body dynamics simulation and fast Fourier transform(FFT),which showed that the amplitude range of unbalanced dual rotors is basically the same as that of the corresponding single unbalanced disk.The definite constant proportion relationships were found between them by comparing the vibration amplitudes among the three steady-state rotating speeds under the same unbalanced condition.The calculation of the Pearson correlation coefficients unveiled that the vibration amplitude is extremely strongly related to unbalance m·e and extremely weakly(negatively)correlated with the distribution of unbalance phase angle for the corresponding unbalanced rotor.In addition,the relevant characteristics were verified synchronously via the tester experiments.Secondly,based on the simulation results of the high-and low-pressure double unbalanced discs,the MARS,RBF,and Kriging models of vibration response estimation were established.The unbalance parameters in the test set were obtained through Monte Carlo sampling with uniform distribution,and then,the vibration response amplitude of each unbalanced condition in the test set was obtained through ADAMS simulation.The three surrogate models estimated the response according to the unbalanced parameters in each working condition in the test set,and The calculation results of the average error rate,mean square error and multiple determination coefficient of the predicted results showed that all the three surrogate models can achieve high precision estimation for the vibration response of unbalanced high-pressure and low-pressure double discs of the dual-rotor system.Finally,based on the theory of nonlinear output frequency response function(NOFRFs)and its derivations,a calculation method of NOFRFs was proposed to locate and diagnose the unbalanced disk(s)of the dual-rotor system.This method requires the vibration time-domain signals of the rotor system in both balanced and non-balanced states at the same speed.In order to meet the requirements of the algorithm,the calculation models of simulation and the experiment with one-dimensional series elements were established.According to the results of simulation and experiment and their consistency,the axial positionings of the single and double unbalanced disks were realized,and the positioning results of the double unbalanced disks were consistent with the results of the corresponding single.