汽轮机叶顶汽封泄漏涡诱导下的压力脉动研究

以某汽轮机级为研究对象,采用三维非定常数值模拟的方法,研究了动叶顶部汽封泄漏涡的涡动特性和泄漏涡影响下汽封腔室内的压力脉动规律。结果表明:叶顶汽封腔室内存在周向螺旋状涡与壁角涡组成的多尺度涡系,涡系的位置和影响范围会随时间经历复杂的变化。叶顶汽封腔室内的压力脉动频率中兼具叶轮旋转的周期性频率和溃散为小尺度涡结构后的高频率。间隙内的多尺度涡结构和动静叶间交替变化的压力场在汽封间隙内的传播是引起汽封腔室内周向压力不均的主要原因。

Investigation on pressure pulsation in the tip seal cavities of a steam turbine induced by leakage vortexes

Taking one stage of a steam turbine as the research object,a three-dimensional unsteady numerical simulation was adopted to analyse the leakage vortex characteristics of rotor tip labyrinth seals.The pressure fluctuation in labyrinth seal cavities affected by leakage vortexes was also studied.The results show that there are multi-scale vortices in the labyrinth seal cavities,which are composed of circumferential spiral vortexes and wall vortexes.The position and the influence range of the vortexes experience complicated changes over time.The frequencies of pressure fluctuation in tip seal cavities contain both the blade passing frequency and the high frequency induced by the tip leakage flow dispersing into small scale vortexes.The uneven circumferential pressure in tip seal cavities is caused by the multi-scale vortex structure of the tip seal leakage flow and the spread of alternately changing pressure field between the stator and rotor blades in the tip clearance.