摘要
在火电机组深度调峰工况下,汽轮机进汽量明显减少,低压缸甚至处于小流量工况下,严重威胁叶片的安全稳定运行。为了研究深度调峰工况下,叶片强度极限内最小流量确定的问题,利用ANSYS-Workbench软件对末级叶片进行流固耦合运算和模态分析。结果表明,最大等效应力与最大变形量所处位置不一致,最大等效应力出现在叶顶,最大变形量出现在叶片中部。随着流量的减小,最大等效应力和最大变形量呈先减小后增大的趋势。G1/G0=0.1时,最大等效应力为451.52 MPa,较额定工况时增加了18.94%,最大变形量为0.72574 mm,较额定工况时降低了7.8%。G1/G0<0.1时,最大等效应力超出强度极限,不满足强度要求。随着流量的减小,叶片固有频率均能避开激振力频率,叶片不会发生共振。综合考虑应力、应变、频率、振型等强度因素,低压缸最小流量不得低于额定流量的10%。
The inlet flow rate of steam turbine obviously is reduced when the thermal power unit is involved in peak load operation,even under the small volume flow condition,which has the great influence on the safety of steam turbine.The fluid-structure coupling and modal analysis of the last stage blade is calculated by ANSYS-Workbench to determine the minimum flow rate within the stress limit of blade under deep peak regulation conditions.The results show that the position of blade maximum equivalent stress is different from that of blade maximum deformation.The maximum equivalent stress is located at the tip of the blade and the maximum deformation is at the middle of the blade.The maximum equivalent stress and maximum deformation decrease first and then increase with the decrease of flow rate.Under G1/G0=0.1 conditions,the maximum equivalent stress is 451.52 MPa,18.94%higher than that at rated working condition.The maximum deformation is 0.72574 mm,7.8%lower than that at rated working condition.The maximum equivalent stress exceeds the stress limit and does not meet the stress requirements under G1/G0<0.1 condition.There is a big difference between the natural frequency and the exciting force frequency of blade,so the blade will not resonate.Therefore,the minimum flow rate of the low pressure cylinder should not be less than 10%of the rated flow rate when the influences of stress,strain,mode of vibration,frequency and other intensity factors are comprehensively considered.
作者
曹丽华
王文龙
罗桓桓
胡鹏飞
王勇
孙亮
CAO Lihua;WANG Wenlong;LUO Huanhuan;HU Pengfei;WANG Yong;SUN Liang(School of Energy and Power Engineering,Northeast Electric Power University,Jilin 132012;State Grid Liaoning Electric Power Supply Co.,Ltd.,Shenyang 110004)
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2020年第16期98-108,共11页
Journal of Mechanical Engineering
基金
国家重点研发计划资助项目(2017YFB0902100)。
关键词
汽轮机
最小流量
流固耦合
模态分析
应力分析
steam turbine
minimum flow rate
fluid-structure coupling
modal analysis
stress analysis
