某型汽轮机调节级气动特性数值研究

Numerical investigation on the characteristics of the guide vane stages in a steam turbine

摘要:

对采用寇蒂斯级设计思想、具有局部进气的汽轮机复速级进行了三维整级数值模拟,分析了设计工况下该复速级的流动特点.计算结果表明,气流流出复速级喷嘴后,每个喷嘴组边界流体的散射作用不强烈,在边界上基本只影响了附近的一个叶栅流道,流动的主体方向沿着轴向进行;当级的压比较大,流动达到超音速时,每个喷嘴组出口流动沿周向的不均匀性非常严重,交替出现尾迹低速区和主流低压区,使喷嘴区域内处于不同位置的动叶片受力状态发生较大变化;超音速喷嘴出现的过膨胀低压区,压力在整个级内是最低的,会加剧动叶流道的非定常流动效应.

Abstract:

Three-dimensional numerical simulation on the double-velocity stage of a steam turbine adopting the design idea of the Curtis stage was carried out.The whole circle flow fields of the two stages were computed and the flow features of the Curtis stage under designed operation were analyzed.Results show that the scattering effect of each nozzle group is not intense after the flow flows out of the Curtis stage nozzle,which only affects one blade passage near the boundary.The main direction of the flow is in the axial direction.When the pressure ratio is relatively larger and the flow velocity becomes supersonic,the circumferencial non-uniform at the outlet of each nozzle group is very serious,the wake aera with low speed and the mainstream area with low pressure appears by turns,so the aerodynamic loads on the rotor blades located at different positions in the nozzle region change greatly.An over-expanded low pressure area occurs in the supersonic nozzle,and the pressure is the lowest in the whole stage,which will strengthen the unsteady effects in the rotor blade passages.