甩负荷工况对汽轮机末级流体激励特性影响研究  

Influence of load rejection condition on the fluid excitation characteristics of the last stage of steam turbine

作　　者：向林嵚 郭冰 李南宜 王光辉 XIANG Linqin;GUO Bing;LI Nanyi;WANG Guanghui(College of Mechanical Engineering,Qinghai University,Xining 810016,China)

机构地区：[1]青海大学机械工程学院,西宁810016

出　　处：《青海大学学报》2025年第1期94-102,共9页Journal of Qinghai University

基　　金：青海大学青年基金项目(2022-QGY-3);青海省科学技术厅项目(2021-ZJ-954Q)。

摘　　要：为探究湿蒸汽非平衡凝结所引发的压力脉动与甩负荷转速飞升诱发的压力波动之间的耦合激励特性,本文基于经典成核理论和液滴生长非等温修正模型,建立综合考虑甩负荷与湿蒸汽非平衡凝结工况的流体激励数值求解模型,研究不同甩负荷工况下机组低压末级的流体激励特性。结果表明:甩负荷工况会引发汽轮机转速飞升,致使叶片压力面流体出现倒流,继而加剧流动不稳定,形成液相聚集,最终使得叶片被液膜包覆,且转速越快,包覆区域越大;甩负荷程度是影响流体激励幅值的主要因素,且甩负荷程度越大,流体激励幅值越大;级内流体不稳定流动是影响流体激励频率的主要因素,100%甩负荷工况下不稳定流动最剧烈,10%工况次之。因此,在实际运行中应避免甩负荷过大或过小的工况。In order to explore the coupling excitation characteristics between the pressure pulsation caused by the non-equilibrium condensation of wet steam and the pressure fluctuation induced by the speed rise of load rejection,based on the classical nucleation theory and non-isothermal correction model of droplet growth,a numerical solution model of fluid excitation considering load rejection and wet steam non-equilibrium condensation conditions was established to explore the fluid excitation characteristics of low pressure last stage of the unit under different load rejection conditions.The results are as follows:The speed rise caused by load rejection condition led to backflow on the pressure surface of the blades,exacerbating flow instability and forming liquid phase accumulation,ultimately resulting in the blades being covered by liquid film.The higher the speed,the larger the coverage area was.The degree of load rejection was the main factor affecting the amplitude of fluid excitation.The higher the degree of load rejection,the greater the amplitude of fluid excitation was.The unstable flow in the stage was the main factor affecting the excitation frequency of fluid,and it was most severe under 100%load rejection condition,followed by 10%condition.Therefore,the condition of too large or too small load rejection should be avoided in actual operation.

关 键 词：甩负荷 流体流动特性 非平衡凝结流动 流体激励特性 转速飞升 

分 类 号：TK262[动力工程及工程热物理—动力机械及工程]