高速旋转的汽轮机隔板密封内流体流动的模拟

Simulation of Flow Within Stepped Labyrinth Seals of Diaphragm in Steam Turbine Under High Rotating Speed Conditions

采用数值求解粘性Navier-Stokes方程,研究考虑轴旋转效应的汽轮机高低齿迷宫式隔板密封内流体流动特性及其影响因素。采用有限体积方法离散控制方程,紊流模型采用标准k-ε两方程模型进行求解。数值模拟了三种齿间距下不同压比时的高低齿迷宫式隔板密封内部的流场特性,并且计算了相应的无量纲流量系数。计算结果揭示了隔板密封内由于环形腔室和高低齿的作用导致密封内流体的动能有效地耗散为热能,起到了密封的作用。研究结果表明:在相同的几何结构下,压比的增加导致密封泄漏量的减小;在相同的压比条件下,密封的泄漏量随着齿间距的减小而减小。

The flow within stepped diaphragm labyrinth seals of steam turbines and their influencing factors, taking into consideration the shaft＇s rotation, is being studied by numerically solving the viscous Navier-Stokes equations. The finite volume method is used for discretizing the governing equations, together with the standard κ-ε two equation turbulent model. The flow within a diaphragm＇ s stepped labyrinth seal is therewith numerically simulated for 3 different tooth spacings and various pressure ratios, obtaining moreover the corresponding dimensionless flow coefficients. Calculation results show that, due to the annular cavity and the stepped teeth conformation, the kinetic energy of the fluid in the cavity is being dissipated and turned into heat, thus effectuating the required sealing purpose. Results also show that, for the same geometrical conformation, the leakage flow coefficient decreases with increasing pressure ratio and leakage is also reduced with reducing the tooth spacing. Figs 6 and refs 4.