Vortex Tracking of Purge-Mainstream Interactions in a Rotating Turbine Stage
Vortex Tracking of Purge-Mainstream Interactions in a Rotating Turbine Stage
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旋转涡轮级中净化与主流相互作用的涡流跟踪
DOI：
10.1115/1.4052690
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Mesny A
中科院分区：
文献类型：
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作者：
Mesny A
在燃气轮机中使用吹扫流允许较高的涡轮入口温度，这是产生高循环效率所必需的。净化空气从压缩机中排出，并重新引入涡轮中，以冷却易受攻击的部件。在相邻的旋转和静止的圆盘之间形成轮空，在通过圆盘外围的轮缘密封进入主流气体路径之前，以低半径提供吹扫空气。当吹扫流出口与主流相互作用时，会招致空气动力惩罚。这项研究展示了来自单级涡轮试验台的无与伦比的三维速度数据，该试验台专门设计用于使用光学测量技术研究出口-主流相互作用。体积测速仪应用于旋转环境，锁相测量用于识别和跟踪叶片通道中的涡流二次流特征。将无吹扫流量的基线情况与清洗质量分数为1.7%的实验进行了比较；选择后者是为了确保车轮空间完全密封。将非局域涡旋跟踪函数应用于数据以识别核心质心的位置。二次流涡的强度由涡丝旋转平面上的环流判据确定。通过实验确定了马蹄形旋涡的压力侧分支和与出口流动相关的第二旋涡。在没有吹扫流的情况下，两个涡合并，形成通道涡(PV)。随着吹扫流的增加，两个核心保持独立于叶片轴弦的40%，同时也显示出增加的径向迁移和PV的强化。结果表明，在吹扫流的作用下，出口核更靠近吸力面。重要的是，在涡旋细丝表现出强烈的径向或切向速度分量的情况下，从轴面计算的环流水平对真实环流的预测不足50%。
The use of purge flow in gas turbines allows for high turbine entry temperatures, which are essential to produce high cycle efficiency. Purge air is bled from the compressor and reintroduced in the turbine to cool vulnerable components. Wheel-spaces are formed between adjacent rotating and stationary discs, with purge air supplied at low radius before exiting into the mainstream gas-path through a rim-seal at the disc periphery. An aerodynamic penalty is incurred as the purge flow egress interacts with the mainstream. This study presents unparalleled three-dimensional velocity data from a single-stage turbine test rig, specifically designed to investigate egress–mainstream interaction using optical measurement techniques. Volumetric velocimetry is applied to the rotating environment with phase-locked measurements used to identify and track the vortical secondary flow features through the blade passage. A baseline case without purge flow is compared to experiments with a 1.7% purge mass fraction; the latter was chosen to ensure a fully sealed wheel-space. A non-localized vortex tracking function is applied to the data to identify the position of the core centroids. The strength of the secondary flow vortices was determined using a circulation criterion on rotated planes aligned to the vortex filaments. The pressure-side leg of the horseshoe vortex and a second vortex associated with the egress flow were identified by the experimental campaign. In the absence of purge flow, the two vortices merged, forming the passage vortex (PV). With the addition of purge flow, the two cores remained independent to 40% of the blade axial chord, while also demonstrating an increased radial migration and intensification of the PV. The egress core was shown to remain closer to the suction-surface with purge flow. Importantly, where the vortex filaments demonstrated strong radial or tangential components of velocity, the circulation level calculated from axial planes underpredicted the true circulation by up to 50%.