汽轮机调节级多工况下三维流场数值研究

Numerical Study on Complex Flow Phenomena in Control Stage with Partial Admission Under Multiple Working Conditions

汽轮机调节级的部分进汽特性,不仅影响到机组的气动性能和效率,而且还对其安全性产生一定程度的影响。基于三维黏性可压缩雷诺时均Navier-Stokes(N-S)方程,采用结构化六面体网格,运用有限容积法,构造了带有进汽室和加强筋的300MW汽轮机调节级三维黏性可压缩计算模型,针对不同运行工况下调节级内部复杂流动进行了详细研究。分析发现:调节级进汽室内部流动损失较大;进汽段下游动叶通道静压分布合理,内部流动顺畅,而非进汽段动叶通道内部流动紊乱,熵增明显,部分进汽带来的损失较大;部分进汽度越小,效率降低越快,尤其是一阀进汽时,效率急剧下降。

The prominently complex effect of control stage with partial admission of stream turbine influences not only the aerodynamic performance, but also the efficiency and safety of unit. Based on the 3D viscous compressible Navier-Stokes （N-S） equations, with the application of structural hexahedron mesh and finite volume method, the numerical model for control stage of 300MW steam turbine with partial admission room and reinforced rib was constructed and the nature of control stage flow was investigated detailed. Muhiple working conditions were performed by blocking different valves. Results show that loss of flow in admission room is comparatively large. In the open channel inside cascade passage, flow is smoother and the static pressure is reasonable, however, in the blocked channel inside cascade passage, blade passage interior is filled with vortex, resulting in the increase of entropy and loss bringing from partial admission. The efficiency decreases with the partial admission ratio; especially under the condition that one valve are open, the efficiency decreases sharply.