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为了找出叶片的失效机理及解决的办法,利用金相、扫描电镜等分析手段,从宏观和微观的角度对叶片及断口进行了观察和分析;用三维有限元法和实验方法对其振动特性进行了研究。分析得出:造成叶片开裂是由于叶片组第2类轴向振动模态和喷嘴叶栅出口气流不均匀引起的激振力频率发生共振,导致叶片高周疲劳造成的。叶根齿表面加工粗糙是裂纹起裂的一个重要诱发因素。采用不改变叶型,仅调整叶片组中的叶片数,成功地实现了叶片的改型设计。该研究表明:叶片组的第2类轴向振动模态同喷嘴激振力共振是危险的,应该避免。调整叶片组中的叶片数是调整叶片组轴向固有振动模态的一个有效方法。图6表3参5
In order to find out the failure mechanism and the solution of the blade, the blade and the fracture were observed and analyzed from macroscopical and microscopic perspectives by means of metallographic analysis and scanning electron microscopy. The three-dimensional finite element method and experimental method were used to analyze the vibration characteristics Were studied. The analysis shows that the blade cracking is caused by the resonance frequency of the exciting force caused by the axial vibration mode of the second type in the blade group and the non-uniform airflow at the outlet of the nozzle cascade, resulting in the high-cycle fatigue of the blade. Rough surface of blade root tooth is an important inducing factor of crack initiation. By changing the leaf shape, only adjusting the number of leaves in the leaf group, the leaf design was successfully achieved. The study shows that: Type 2 axial vibration of the blade group with the nozzle excitation force resonance is dangerous and should be avoided. Adjusting the number of blades in the blade group is an effective way to adjust the modes of natural vibration in the blade group. Figure 6 Table 3 Reference 5