为了进一步认识匹配应用迷宫汽封和平衡孔对透平级气动性能的影响,采用商用软件CFX,数值仿真了某汽轮机高压一级半透平、堵住平衡孔的一级半透平内部的三维流场.通过对计算结果的比较分析发现,转子带凸台的高低齿迷宫式汽封,与转子外径相等、同压比的等齿高直通型迷宫汽封相比,泄漏流动的方向折转以及在汽封腔内形成的旋涡显著增多,因此强化了对泄漏流的阻抗及其动能的耗散,提高了汽封的封严性.对于低反动度透平级,气流对动叶栅的直接冲击是级内轴向力产生的主要原因.叶冠的径向高度远小于叶高,但是叶冠产生的轴向力在级轴向力中占有较大比例.平衡孔需要与前后静叶隔板汽封以及动叶前后轴向间隙汽封匹配设计,设计合理,能够消除泄漏流对主流的干扰,降低透平级的流动损失.%In order to further understand the influence of the matching application of the labyrinth seal and the balance hole on aerodynamic performance of turbine stage, numerical simulation on the three-dimensional flow field of one and a hah0 turbine stage, and one and a half turbine stage with blocking the balance hole of a high-pressure steam turbine was carried out by using commercial software CFX in this paper. The results shows, compared with the equal tooth height straight-through labyrinth seal with the same diameter as rotor and the same pressure, the stage tooth labyrinth seal of the rotor with process platform, can increase the turning of leakage flow direction and the vortex formed in the seal chamber significantly, so strengthen the impedance of the leakage flow and its kinetic energy dissipation, and improve the sealing characteristics of the seal. To the turbine stage with low reaction degree, the direct impact of the flow on the rotor cascade is the main reason of the axial force. The radial height of the blade tip shroud is far less than the blade height, but the axial force generated by the blade tip shroud is a large proportion in the stage axial force. The matching design of balance holes with the front and rear diaphragm seal and rotor blades axial clearance seal must be done, if the design is reasonable, which can eliminate the interference of leakage flow to mainstream, and reduce the flow loss of turbine stage.
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