Fall-block Failure Analysis of Centrifugal Impeller of Micro Turbojet Engine
In the ground test process of a micro turbojet engine,the kurtosis factor appeared abnormal,far exceeding the normal value of 3,in the case that the fundamental frequency of vibration acceleration and the total vibration velocity did not exceed the limit.After stopping test and decomposition,it was found that one blade of the centrifugal impeller had a large fall-block at tip,and the other blades had small notches at different positions of the leading edge.The monitoring parameters during test was analyzed,and it was found that the blades had scraped with the centrifuge cartridge.Through macroscopic inspection,it is judged that the tip fall-block of the blade is initial fracture.Through fracture analysis,it is determined that the tip fall-block of the blade is high-cycle fatigue fracture caused by the leading edge cracking.Combined with the finite element analysis of the resonance speed and vibration stress distribution of the centrifugal impeller,it is determined that the high order vibration induced by the radial diffuser blade is the main cause of blade fracture.By changing the centrifugal impeller material,optimizing the blade profile and increasing the root chamfering,the inherent frequency of the blades can be changed and the anti-high cycle fatigue performance of the blades can be enhanced.As a result,such failure can be prevented.
centrifugal impellerfall-blockhigh cycle fatiguehigher order vibration
万方数据
维普
