刷式密封对透平级气动性能影响的研究

采用基于非线性Darcian多孔介质模型三维Reynolds-Averaged Navier-Stokes(RANS)和SST紊流模型的泄漏流动数值方法对比研究了动叶叶顶迷宫密封和刷式密封的1.5级汽轮机高压缸透平级的气动性能.数值预测实验测量的刷式密封泄漏量与实验数据吻合一致,验证了数值方法的可靠性。详细分析了动叶叶顶迷宫和刷式密封两种结构对1.5级透平级叶顶间隙泄漏特性和气动性能参数的影响特性.结果表明:在相同工况下,相比于叶顶迷宫密封结构,叶顶刷式密封可使透平级级效率提高0.15%,叶顶间隙泄漏量降低30.74%。叶顶刷式密封和迷宫密封结构对透平级反动度和动叶出口气流角的影响基本相同.叶顶刷式密封中刷丝束前后压降大于迷宫密封中相同位置处迷宫齿前后压降,刷丝束起主要封严作用.

Effect of Brush Seal on the Aerodynamic Performance of Turbine Stages

The aerodynamic performance of 1.5 high pressure cylinder steam turbine stage with rotor blade tip labyrinth and brush seals is numerically investigated using three-dimensional ReynoldsAveraged Navier-Stokes(RANS) and SST turbulence model based on non-linear Darcian porous model.The numerical prediction of the leakage flow rate of experimental brush seal is well agreement with the experimental measurements.The reliability of the presented numerical method is validated.Effect of the rotor blade tip labyrinth and brush seal on the tip leakage flow rate and aerodynamic parameters of turbine stage is analyzed in detailed.The obtained results show that the aerodynamic efficiency of turbine stage with rotor blade tip brush seal increases up to 0.15% by comparison of the labyrinth seal.In addition,the tip leakage flow rate of brush seal decreases by 30.74% by comparison of labyrinth seal.The similar influence of the rotor tip brush and labyrinth seal on the reaction degree and rotor blade exit flow angle is obtained.Brush seal performs better in sealing performance as the pressure drop across bristles is higher than that across the labyrinth tooth at the same location in labyrinth shroud seal.