A new blade-casing rubbing model and its verification

For the aero-engine blade-casing rubbing fault,a new blade-casing rubbing model was put forward.On the basis of tranditional elastic rubbing model,the new model considerd the effects of blade number and the rotor-stator clearance change on rubbing forces,and it could simulate rubbing faults with various rubbing positions including singlepoint,multi-points,part and whole-cycle on casing and rotor.The new rubbing model was applied to the rotor-support-casing coupling dynamic model,and the casing acceleration responses under rubbing faults were obtained by the numerical integration approach.The aeroengine rotor tester including casing was used to carry out the rubbing test whose rubbing positions were the single-point on casing and whole-cycle on rotor,and it is found that the rubbing characteristics of the casing vibration acceleration signals have obvious periodic impact characteristics.The impact frequency is the frequency of the blades passing the casing,which equals to the product of the rotational frequency and blade number.There is a blade passing frequency and its multiple-frequency components in the high-frequency band ofspectrum,and the impact is modulated by the rotational frequency.There are obvious quefrency components of rotational frequency components and its multiple frequencies in the signal cepstrum.The simulation results agree well with the test values,and the new blade-casing rubbing model is fully verified.Finnaly,based on the new blade-casing rubbing model,the other rubbing modes between rotor and casing were simulated,and the casing vibration charateristics were obtained.