Common aircraft engine rotor system vibration fault

2020 - common aircraft engine rotor system vibration fault 01 - 31 Zhang Tiancheng tianjin university survey, about 50% of China's domestic aircraft fault is the result of the engine. Aeroengine fault type is complex, generally can be divided into performance system fault fault, structural strength and accessories. From found in aeroengine fault statistics in our country, the engine performance failure accounted for about 10% ~ 20% of total failure, structural strength failure accounted for about 60% ~ 70% of total failure. But in either case, the fault of the precursor and development process is on the vibration of motor rotor. The rotor system is the core of the aircraft engine system, once appear, fault, then affects the work, little is causing serious destructive accidents. , therefore, to study various factors caused by the vibration of the aeroengine rotor system phenomena and mechanism, and is an important task to study the dynamics of the aircraft engine. Through research, can provide theoretical basis for the effective fault diagnosis and control, also can to solve the key mechanical problems in the design of advanced aircraft engine independent provides theory basis. Aircraft engine vibration related common faults as follows: 1. Sages stator rubbing fault due to the pursuit of high ratio and low consumption, the speed of the aircraft engine is higher and higher, and the rotor and the clearance between the static son more and more small, thus deepening the rubbing between the stator son the probability of failure. Rubbing between the stator son once happened, would make the increase of the gap between stator son thus reduce its efficiency, serious when still can make a broken blade. And seal structure of rubbing between shaft and can make the seal structure is damaged, and makes a partial fever to hot bending and axial vibration is increasing. Son at the same time, the stator rubbing will cause the coordinate rotor precession, and thus to produce alternating stress in the rotor, rotor fatigue damage. 2. In the wrong after loosening, installation error, bearing the basis of fault deformation and the thermal expansion of the work, can cause the shaft between the fault in the wrong. No fault causes the rotor in axial and radial alternating force, which result in the axial and radial vibration of the rotor, thus cause bearing wear, axis deflection and rubbing between the rotor and the static son, etc. 3. Unbalanced thermal bending faults of manufacture, assembly and the starting process to produce hot bending, is the important reason for the aeroengine rotor produce larger vibration. Rotor hot bending, usually occurs in the cooling process of engine after parking, due to the natural convection heat transfer, lower than the upper rotor cooling speed, rotor of the upper and lower surface temperature difference and produce certain hot bending, a bow, resulting in a larger imbalance. When starting again, the increase of the vibration response, and even produce static son rubbing fault. 4. Blade vibration fault aeroengine rotor blade working conditions, blade resonance, flutter problem such as fatigue fracture, has been the important reason for the engine failure. Blade vibration serious will cause of blade fracture and fly, blade loss caused by the sudden imbalance, more will cause large transient vibration, often lead to instability of rotor and stator rubbing, blades and shaft cracks, loose structure and a series of failures. 5. Looseness fault under long-term cycle under the action of cyclic loading, vibration caused by the bending fatigue and plastic deformation, the engine's connecting bolt looseness happens, fall off, lead to the lack of support stiffness and cyclical change, resulting in abnormal engine rotor structure vibration. Looseness fault is often accompanied by other faults, such as medium. 6. Fatigue crack fault of engine rotor under high temperature, high speed and mutation load, easy to produce fatigue crack, and constantly expand until a fracture. 7. Rolling bearing fault in high speed rotary compressor, turbine aircraft engine system, the rolling bearing is still a prone to failure of components. Field studies show that about 90% of the rolling bearing fault is associated with the defects of inner ring or outer ring, the other 10% is associated with the failure of rolling element or cage. Other rolling bearing in strongly nonlinear factors, to solve the problem of rolling bearing fault, its nonlinear dynamics mechanism should be further investigated. Aeroengine rotor system failure mode, mechanism more complex, more important is all the fault is often not a single, a failure usually triggers or with other malfunction. The existence of a variety of fault coupling and nonlinear factors, greatly increased the difficulty of the dynamic analysis, this for our research work has brought great challenges and opportunities. （ Source: mechanical WeChat public walk)