【作者】 张家忠； 刘雁； 王平；

【Author】 ZHANG Jia-zhong~1 LIU Yarr WANG Ping~1 (1.School of Energy and Power Engineering,Xi’an Jiaotong University,Xi’an 710049,China,2.Department of Mechatronics Engineering,Northwestern Polytechnical University,Xi’an 710072, China)

【机构】 西安交通大学能源与动力工程学院； 西北工业大学机电工程学院；

【摘要】 离心叶轮是一类典型的循环周期性结构,其具有不同于非循环周期结构的许多特殊的动力学性质,如:存在频率通带(passbands)和禁带(stopbands)现象。当激振频率处于通带区域内时,其振动模态和能量在整个结构内均匀分布;而当激振频率处于禁带区域内时,振动幅值和能量主要限制在结构的某一局部区域内,使得结构该部位的响应幅值及应力过大,并产生能量积聚,最终将导致叶轮发生疲劳破坏。同时,在实际中由于制造误差、材料和使用中磨损出现的不均匀等多种因素将导致离心叶轮的周期性结构失谐。对于协调结构,其失谐后,在一定条件下(如系统具有高密集模态,离心叶轮具有此性质),很小的失谐量就可使结构振动模态产生急剧变化,从而出现振动模态局部化现象。基于现有的有限元分析方法,结合模态分析技术等动力学理论、叶轮所承受的激励等,主要分析在流体介质激振的频率接近叶轮的某一禁频带时,叶轮的相应部位出现较大的振动,而发生叶轮疲劳破坏的原因。更多还原

【Abstract】 Centrifugal impeller is the typical periodic structure,and there exists many unique dynamics in comparison to non-periodic structure,such as the passbands and stopbands.The amplitude and the resulting energy will be uniform in the structure as the exciting force in the range of passbands.On the other hand,the amplitude and the resulting energy will be limited at local part,and the amplitude and stress will be increased greatly,the centrifugal impeller will be destroyed as the energy is localized. Additionally,the influence of mistuning from the manufacture process,material and wear on the dynamics of the system is significant.For some cases,such as the structure with dense modes,small mistuning will lead to great change of the mode, resulting localization of vibration. Finite Element Method and modal analysis are used to investigate the local vibration with large amplitude and train,as the exciting frequency is increased within the stopband of centrifugal impeller.Such mode localization is the key to the fatigue failure of the centrifugal impeller and some strategies will be presented for such fatigue failure.更多还原