空心静叶汽膜孔排吹扫除湿的数值研究
Numerical Investigation on Steam Film Holes Blowing for moisture removal on Steam Turbine Hollow Blade Surface

为了降低蒸汽轮机末级叶片表面的蒸汽凝结和水滴沉积、抑制水膜形成,通过借鉴燃气轮机气膜冷却思想提出在汽轮机空心静叶表面设置离散的汽膜孔排进行吹扫除湿,使用ANSYS？？CFX软件求解了三维定常黏性雷诺时均N？？S方程,采用k？拨赝牧髂Ｐ图氨诿婧？数法数值研究了孔排吹扫除湿性能及其对叶栅主流场的影响。结果表明:当吹汽比小于1.0％时,静叶表面能够形成良好的热汽膜层,叶片表面湿度降低明显且对主流影响较小;随着吹汽比的增大和吹扫温度的提高,叶栅出口的平均湿度降低,主流的流动效率急剧降低。综合考虑叶片表面湿度和主流的流动效率,在所提除湿结构和0.5％～1.0％吹汽比下除湿效果最好。该结果为开发汽轮机新型高效的除湿方式提供了有益的探索。
To reduce the steam condensation and moisture deposition on the last stage of steam turbine, three rows of disperse steam film holes are set on the surface of a hollow stator blade with the reference of the gas turbine film cooling system. The moisture removal performance of this method and its influence on the blade main flow field are numerically investigated by solving the 3？？D Reynold time averaged Navier？？Stokes equation with the ANSYS？？CFX commercial code, as well as the k？拨？ turbulence model and the wall function. The results show that when the steam blowing ratio gets less than 1.0％, the hot steam film on the blade surface is prone to form and the wetness of the surface declines apparently, and this level of blowing ratio slightly affects the main flow. With the increase of the blowing mass flow rate or the blowing temperature, the averaged cascade outlet wetness decreases, however, the flow efficiency of the main flow decreases sharply in consequence. Considering the blade surface wetness and the main flow efficiency, the best moisture removal performance can be achieved in this designed structure as the steam blowing ratio is taken between 0.5％ and 1.0％