端壁侧向出流对透平轮缘密封的影响及优化

Analysis and Optimization of Interaction between Endwall Flank Flow and Turbine Rotor-Stator Rim Seal

关键词:  透平转静轮缘  燃气入侵  端壁侧向出流  非均布出流孔  密封效率

Key words:  Turbine rotor stator clearance  Hot gas ingress  Endwall flank flow  Non-uniform distribution holes  Sealing effectiveness

摘要:

在燃气轮机的设计研究中，用于冷却静叶端壁的气体会有一部分从端壁的侧面沿轴向流出，这部分气体恰恰处在轮缘间隙密封流体和主流的交互作用区。采用数值模拟的方法研究了真实工况下端壁侧向出流与动静叶间隙密封流的相互影响，分析了其作用机理并在此基础上提出了一种新型的非均匀布置出流孔结构。结果表明端壁侧向出流能够抑制主流侵入涡系的大小和深度，当端壁侧向出流量 R m =10%能够将密封间隙冷却60～80K；新提出的非均匀布置端壁侧向出流孔结构能改善对静叶尾缘附近这些燃气入侵严重区域的密封效果， R m =10%的情况下非均匀出流形式在静叶尾缘区域的密封效率能够提高3%左右。

Abstract:

For certain gas turbines，parts of endwall cooling flow go out of its side axially and mix with sealing flow. This mixing process happens in rotor stator clearance where main flow and sealing flow interacts. Therefore，it is very important in gas turbine rim seal design. A validated numerical method was used to investigate the interaction mechanism between endwall flank flow and sealing flow under the influence of external flow，and one new and more efficient hole distribution structure named as non-uniform distribution holes was presented and studied. It is found that endwall flank flow can increase sealing effectiveness by restraining the size and depth of ingestion bubbles size and the cooling effect for rotor stator clearance is 60～80K when endwall flank flow rate is R m =10%. Non-uniform distribution hole can optimize the sealing effectiveness about 3% around the vane trailing edge where more serious hot gas ingestion happens.