汽轮机自带冠阻尼叶片强度与振动特性有限元分析

Finite element analysis of strength and vibration characteristics of steam turbine shrouded blade

以某给水泵汽轮机自带冠叶片为研究对象,采用循环对称法建立汽轮机自带冠叶片—轮盘系统模型,利用有限元方法研究该叶片的应力分布及固有模态,将对汽轮机内部进行三维非定常流场分析得到的实际工况下气流激振力施加到叶片上,采用模态瞬态动力学方法分别研究系统在VWO(阀门全开)以及30%THA(热耗率验收)两种工况下的振动响应规律。研究表明:冠间阻尼使得整圈叶片在工作状态下处于整圈自锁状态,增大了系统原有刚度,可有效降低叶根以及轮盘槽的最大等效应力,避开“三重点”共振,使机组安全稳定地运行;冠间干摩擦阻尼结构能够消耗振动能量,使振动响应大幅度降低。两种工况下的计算结果对工程实际有一定参考价值。

With a shrouded blade of a feed-water pump turbine as the object of study,the model of the shrouded-disc system of a steam turbine was established by using the cyclic symmetry method.The stress distribution and the inherent mode of the blade were studied by using the finite element method,and the flow-induced vibration force was applied to the blades under the actual conditions obtained from the three-dimensional unsteady flow field analysis of the turbine interior.On the blade,the vibration response of the system under VWO(full valve opening)and 30%THA(heat consumption rate acceptance)conditions was studied by using the modal transient dynamics method.The results show that the inter-crown damping made the whole-circle blade self-locking in the working state,increased the original stiffness of the system,effectively reduced the maximum equivalent stress of the blade root and the disk groove,avoided the“triple junction”resonance,and made the unit operate safely and steadily;the inter-crown dry friction damping structure could consume vibration energy.The vibration response was significantly reduced.The calculated results under two working conditions had certain reference value for engineering practice.