Analysis And Study On Typical Vibration Faults Of Aeroengine

Due to the complexity of aeroengine structure,and its high rotation speed,poor and frequently changed working conditions,vibration faults of aeroengine are diverse and the related failure mechanisms are extremely complicated.According to statistics,more than 70%of the faults in the aeroengine are related with vibration,and recently more than 80%of the big accidents happened in our domestic aeroengines is caused by the vibration faults of rotor system,especially the following two types of typical vibration faults,such as rubbing fault and oil-leakage fault in the rotor system.For example,rubbing fault will not only lead to the increasing clearances between the rotor and stator which result in worn bearings and cracked or even broken blades,but also may cause instability movement of the rotor system and large deformation of the casing which will seriously affect the working efficiency and safety of aeroengines.Besides,the harmful effects of oil-leakage fault is also huge,oil-leakage phenomenon will lead to formation of oil cluster in the rotor cavity,when asynchronous precession happens due to the differences between precession frequency of oil cluster and the frequency related to critical speed,strong self-excited vibration will occur in the rotor system,which will not only induce excessive vibration and a variety of noise in medium and low frequency band,but also lead to severe security accidents,e.g.,the spinning drum might be cracked or even damaged.Therefore,it is of great scientific and engineering significance to studytypical vibration faults of aeroengine structure.Even though a series of research achievements have been made and abundant research efforts have been focused on vibration fault problems of aeroengine,such as the whole body vibration fault,the rotor system vibration fault,gear vibration fault,oil whirl and oscillation faults,the measured vibration fault data,e.g,rubbing fault and oil-leakage faults based on experimental rig and aeroengine bench have not been well used by now,and the related fault mechanisms as well as test techniques have not been studied deeply and systematically,because for the vibration fault of the rotor system,currently most of studies are limited on rotor imbalance,rotor misalignment,crack faults and etc.Therefore,it is necessary to combine theory with experiment to study the dynamic characteristics of rubbing fault and oil-leakage faults of aeroengine structure.On one hand,to determine how its inherent characteristics and vibration response characteristics are affected by above faults.On the other hand,to explore and develop the new experimental equipments and test techniques for rubbing fault and oil-leakage test,which can be used to verify the correctness of theoretical methods and their results.Based on the self-design rubbing rotor experimental rig and oil-leakage rotor experimental rig,this research combines theory with experiment to investigate on the dynimc mechanisms of rubbing fault and oil-leakage fault of aeroengine and related test techniques.Besides,the actual rubbing fault test and oil-leakage fault test of a certain type of aeroengine have been conducted based on aeroengine bench,and characteristics of two kinds of fault signals have been analyzed and summarized.The main content of this research is as follows:(1)Because it is difficult to conduct rubbing fault test on the real aeroengine,rubbing rotor experimental rig is designed and assembled.Based on this rig,dynamic characteristics of single rotor and dual rotors have been firstly analyzed respectively and consequently experimental tests for single rotor rubbing and double rotors rubbing with simulations have been carried out to verify effectiveness and correctness of the theoretical analysis method.(2)Because it is also difficult to conduct oil-leakage fault test on the real aeroengine,oil-leakage rotor experimental rig is designed and assembled.Firstly,an analytical method and ADAMS simulation method have been adopted to analyze dynamic characteristics of oil-leakage rotor system.Then,vibration characteristics of the oil-leakage rotor system under different media(water or oil)and different volume of oil cluster have been measured to verify effectiveness and correctness of ADAMS simulation method(3)The rubbing fault test and oil-leakage fault test of a certain type of aeroengine have been conducted based on actual aeroengine bench,and the fault signal data of the real aeroengine have been obtained.Then,the related fault mechanisms as well as spectrum characteristics have been analyzed and summarized,and the results can also be used to verify fault analysis conclusion based on above two kinds of experimental rigs at some level.This research can contribute a lot to provide theoretical foundation for the monitoring and diagnosis of rubbing fault of aeroengine,to provide data support for early diagnosis and prediction of oil-leakage fault,and to provide theoretical and practical reference for establishing test and analysis methodology of rubbing fault and oil-leakage fault of aircraft engine.