汽轮机阀门活动试验工况下高压第一级动叶热应力分析

Thermal Stress Analysis of High-Pressure First Stage Blade under Valve Movability Test Condition of Steam Turbine

针对阀门活动试验工况下的叶片安全问题,以某1 000 MW核电汽轮机组高压缸第一级动叶片及其进汽腔为研究对象,通过商业仿真软件ANSYS,对机组额定工况以及95%和85%额定工况下的阀门活动试验工况进行了数值模拟,并通过瞬态流-热-固耦合方法,对进汽腔后第一级动叶进行了热应力及变形分析。结果表明:在全周进汽下,调节阀关闭使进汽腔后出现非均匀流场,动叶热应力受流场影响有较大波动,3种工况下叶片所受极值热应力在18~55 MPa之间,叶片瞬态最大变形量在0.498~0.52 mm之间;降低至机组额定功率的95%和85%进行阀门试验,使叶片平均极值热应力分别上升15.1%和23.2%,由于热应力极值小于材料的疲劳极限,认为95%和85%额定功率下的阀门活动试验对叶片安全运行产生威胁不大。

Aiming at the safety problems of the blade under valve movability test condition, a 1 000 MW nuclear steam turbine unit′s high-pressure cylinder inlet cavity and its first stage blade were taken as research target, and the valve movability test conditions under rated operating conditions and 95% and 85% operating conditions were numerically simulated by commercial simulation software ANSYS. The thermal stress and deformation analysis of first stage blade at the rear of steam inlet cavity was carried out by using the transient fluid-thermal-structural coupling method. The results show that under the full-arc admission, the closing of the regulating valve causes a non-uniform flow field after the steam inlet cavity, and the thermal stress of the blade is influenced by the flow field with large fluctuations, and the extreme thermal stress of the blade under the three operating conditions is within 18 MPa to 55 MPa, and the maximum transient deformation of the blade is within 0.498 mm to 0.52 mm. The average extreme thermal stresses of the blade for valve test rise 15.1% and 23.2% respectively under 95% and 85% platform power, due to the extreme value of thermal stress is less than the fatigue limit of the blade material, it is considered that valve movability test under 95% and 85% platform power pose little threat to the safe operation of the blades.