1000MW机组汽轮机末级叶片除湿缝结构设计与优化

Optimization design of dehumidification structure of the last stage blade in a steam turbine

以某1 000 MW机组汽轮机末级叶片为对象,采用CFX软件对该汽轮机末两级叶栅内凝结流动及水滴沉积过程进行了数值模拟,计算分析了除湿缝的缝隙位置、角度、宽度及数目对除湿效率、二次水滴去除率和级效率的影响。结果表明:为保证末级叶片同时具有较好的除湿性能、级效率和静叶刚度,除湿缝结构应设计在相对叶高60%以上,且在压力面和吸力面相对叶宽80.6%和29.2%处;除湿缝角度选取45°,除湿缝宽度采用1.0mm;若不考虑空心静叶的强度问题,单段除湿缝的综合性能更优;当开缝面积相同时,双缝除湿缝的各项性能均更优;当开缝宽度相同时,单缝除湿缝的综合性能更优。

Taking the long last stage blades of steam turbine in a 1 000 MW unit as the research objects,the condensation flow and droplet deposition in the last two stages were numerically calculated by CFX software.Effects of such dehumidification structure design parameters as the slot position,slot angle,slot width and slot number on the humidification efficiency,second water droplet removal rate and stage efficiency were investigated in detail.The results show that,to ensure excellent performance for the last stage blades,like well humidification property,high stage efficiency and great stationary blade strength,the moisture removal suction slots should be located at the place higher than 60%of the relative blade high in radial direction,and in the axial position of 80.6% and 29.2% relative blade width on the pressure and suction surfaces respectively.In addition,the slot angle should be 45°and the width ought to be 1.0 mm.If not considering the hollow stationary blade＇s strength,the single-stage humidification slot had better comprehensive performance.With the same slot area,the double-slot humidification slot was better.When the slot width is the same,the single-slot humidification slot was better.