某型燃气轮机封严盘疲劳裂纹机理分析

为了系统研究某型燃气轮机封严盘疲劳故障的现象、机理、特点和原因,进行了封严盘故障损伤痕迹、断口形貌、材料成分、金相组织等分析;同时进行了强度(应力)和模态振动特性方面的有限元计算研究,在此基础上进行了共振特性分析。分析结果表明:该封严盘结构设计存在薄弱环节,其均压孔孔边径向应力水平高,孔边表面状态不佳,在一定振动应力作用下,均压孔边容易产生高周性质的疲劳裂纹。对防止某型燃气轮机封严盘产生疲劳裂纹失效提出修理和使用中应控制的要点。

Fatigue Cracking Failure Mechanism Analysis of a Gas Turbine Sealing Disk

To systematically study the fatigue failure phenomenon, characteristic, forming mechanism and root cause of a gas turbine sealing disk, the damage impression, fractography, material composition and metallurgical structure of the damaged section were analyzed. Resonance vibration analysis was performed based on the results from strength (stress) finite element calculation and vibration modal analysis. The final results show that there are weak points in the structure design of the sealing disk. High Cycle Fatigue(HCF) cracks under certain vibration stress are generated easily as a result of high radial stress on edges of the pressure-balanced holes and their bad surface conditions. The key points to prevent fatigue cracking failure for a gas turbine sealing disk both in repair and in service are suggested.