汽封与平衡孔对透平级气动性能影响的数值研究

Numerical Study on the Effect of Steam Seal and Balance Hole on the Aerodynamic Performance of Steam Turbine Stage

为了进一步认识汽封和平衡孔对透平级气动性能的影响,以某汽轮机末三级为研究对象,进行含汽封和平衡孔透平级的全三维数值计算。发现设置汽封和平衡孔以后,焓降相比无汽封和平衡孔的情况降低焓降减少3.28%,总总等熵效率下降2.5%,同时轴向推力减少了7.14%,机组气动性能下降但安全性提升。另外由于汽封的抽吸作用,叶片顶部和底部的展向涡被削弱,从而减少二次流损失。机组设计中应通过对汽封及平衡孔与叶片之间的匹配优化设计以减小泄漏损失,提高通流效率。

In order to further understand the influence of steam seal and balance hole on the aerodynamic performance of the turbine stage,the last three stage of a steam turbine was taken as the research object and the full three-dimensional stage with steam seal and balance hole was numerically simulated.It was found that,with steam seal and balance hole,the enthalpy drop decreased by 3.28%,the total isentropic efficiency decreased by 2.5%,the axial thrust decreased by 7.14%,and the aerodynamic performance of the turbine decreased but the safety of the turbine improved significantly after setting the steam seal and balance hole.In addition,due to the suction effect of steam seal,the spread vortex at the top and bottom of blade is weakened,thus reducing the secondary flow loss.During the turbine design,the matching optimization design between steam seal,balance hole and blade shall be carried out to reduce the leakage loss and improve the throughflow efficiency.