静调引风机变转速运行叶片开裂机理研究及解决方案

Research on Blade Cracking of Static Blade Adjustable Induced Draft Fan at Variable Speed Operation

针对汽轮机驱动的静叶调节轴流引风机叶轮叶片开裂故障问题,对引风机叶轮本体进行了有限元静力学和模态数值计算及现场测试,结合理论计算结果和现场实测结果,对叶片产生裂纹的机理进行分析。有限元静力学计算结果表明,叶片开裂位置的叶片应力为312MPa,安全系数达2.24,满足设计裕量要求。分析结果表明,叶片在风机变速运行过程中存在共振现象是其断裂的主因。叶片发生共振时,受力强度激增,从而对引风机叶片寿命产生负面影响,发生疲劳断裂。最后,建议通过采用风机分档运行的办法来处理叶片开裂问题。

Aiming at the cracking failure of steam-driven induced draft fan,finite element static calculation,modal calculation and thermal state test were carried out,and the mechanism of blade cracking was analyzed.The results of finite element static calculations indicate that the blade stress of the blade cracking position is 312MPa and the safety factor is 2.24.The requirement of design margin is met.The analysis results show that the resonance phenomenon of the blade during the variable speed operation of the fan is the main reason for fracture.When the blades resonate,the stress intensity increases sharply,which has a negative impact on the life of the induced draft fan blades,leading to fatigue fracture.Finally,it is recommended to solve the problem of blade cracking by adopting the method of fan operation in different speed stages.