Investigation of the factors influencing the damaging and destruction of compressor blades of aircraft engine
Aerospace propulsion engineering
Moscow State Technical University of Civil Aviation, 20, Kronshtadskiy Bulvar, Moscow, 125993, Russia
With the help of the suggested methods for researching dynamic tensions of compressors blades at resonant oscillations at high modes the area of occurrence and the subsequent development of fatigue cracks up to the final breakage can be defined. The problem of foreign objects distribution in the engine compressor has many aspects. Great complexity of processes and phenomena, variety of the factors at the same time operating and connected among themselves, often controversial complicate the full solution of this problem.
In the analysis of the reasons of blades destruction in operation and the identification of hazardous forms of oscillations it is necessary to analyze of the excitation forces frequencies (for probable harmonics) and range of their natural modes and frequencies of the studied blades.
From the nature of all the compressors blades fatigue failure it can be seen that all the blades regardless of their size and material are destroyed in a clearly restricted areas on the back, edges, end. The relative coordinates of the location of the cracks are approximately the same.
This indicates the general regularities of the blades dynamic loading andthe emergingtensionsin themat resonantoscillations.And the presenceof operationaldamageon the bladesdoes not influence on these regularities.
As we know fromsad exploitation experience,evengettingasmall portion ofthe destroying blade in the gapbetween the casing and the otherblades tips can leadto the titaniumfire.Obviously,the presence of manysuch fragmentsincreasesthis probabilityby several times and, at best, definitelycauses engine damage.
According to the results of the exploitation observation works the nature of the detected failures allows you to distinguish dangerous resonances and to determine the frequency and the excitation harmonics.
The main objective — revealing of the destruction reasons is achieved. That allows you to develop measures on suppression of defects.
Keywords:high pressure compressor, aircraft engine, compressor blades, fatigue failure, form of oscillation, maximum nominal strain
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