汽轮机叶顶汽封间隙泄漏涡动特性研究

采用三维非定常数值模拟的方法,研究叶顶汽封间隙泄漏涡的结构和涡动频谱特性,并分析汽封各腔室内涡核中心点的径向高度随间隙的变化规律。结果表明:汽轮机叶顶汽封腔室内存在腔室涡和围带壁面涡2种稳定耗散的涡;随着叶顶间隙高度的增加,围带壁面涡涡核的径向高度降低,而腔室涡涡核的径向高度升高;从汽封的入口到出口,腔室涡的涡动随流动变得剧烈,频率增加,波动的幅度变大;围带壁面涡的涡动会在不同腔室内交替变换,齿前的围带壁面涡产生的压力波动最为剧烈,是汽封腔室内最不稳定的一类涡动。

Research on Vortex Characteristics of Leakage Vortex in Tip Labyrinth Seal of Steam Turbine

A three dimensional unsteady numerical simulation was adopted to research the structure and the frequency spectrum characteristic of the leakage vortex in the tip labyrinth seal cavity.The variation law of radial height with clearance of vortex core in each cavity of labyrinth seal was analyzed.The simulation results show that, there are two stable dissipative vortices in the tip seal cavity of steam turbine,the cavity vortex and the shroud wall vortex.With the increase of tip clearance,the radial height of vortex core is decreased and the radial height of vortex core is increased.From the inlet to the outlet of the tip labyrinth seal,the vortex in the cavity becomes violent with the flow,the frequency is increased and the amplitude of the fluctuation becomes larger.The shroud wall vortex changes alternately in different cavities.The front tooth wall vortex is the most unstable type of vortex in the tip labyrinth seal cavity,in which the pressure fluctuation is the most severe.