燃气透平轮缘密封流动特性和气动性能  

Research on Flow Characteristics of Rim Seal and Aerodynamic Performance of Gas Turbine Stage

作　　者：赵欣悦 雷隆 李志刚[1] 李军[1] ZHAO Xinyue;LEI Long;LI Zhigang;LI Jun(Institute of Turbomachinery,Xi’an Jiaotong University,Xi’an 710049,China)

机构地区：[1]西安交通大学叶轮机械研究所,西安710049

出　　处：《西安交通大学学报》2024年第5期111-123,共13页Journal of Xi'an Jiaotong University

基　　金：国家科技重大专项资助项目(J2019-Ⅱ-0010-0030,J2019-Ⅱ-0011-0031)。

摘　　要：轮缘密封是二次空气系统的重要组成部分,能有效抑制燃气入侵盘腔,但过量的封严冷气进入主流会显著影响透平气动性能。采用数值求解三维非定常雷诺时均纳维斯托克斯(URANS)方程组和剪切应力传输(SST)k-ω湍流模型的方法研究了燃气透平轮缘密封流动特性和气动性能。数值模拟得到的轮缘密封封严效率与实验数据吻合良好,验证了数值计算方法的可靠性。研究了3种封严冷气量下的透平轮缘密封的封严效率和气动性能,分析了透平静动盘腔的流场结构和燃气入侵与冷气出流特性。仿真结果表明:在所研究的3种封严冷气流量下,轮缘密封内腔完全封严,较小的封严冷气流量能使末级透平轮缘密封达到较高封严效率;在最小冷气流量时外腔动盘面平均封严效率比静盘面高4.4%。对于末级透平,主流周向压力不均匀分布导致的外环诱导入侵占主导,且动叶前缘附近压力场对燃气入侵的影响大于静叶尾迹压力场。封严冷气质量流量比每增大1.0%,透平级总总效率降低约1.0%,相对动盘壁面封严效率的影响,封严冷气流量对动叶气动性能的影响更大;出流冷气的流动方向相对主流在切向上滞后,使掺混气流以负攻角冲击动叶吸力面前缘,吸力面前缘压力增大。该工作可为轮缘密封流动特性及其对透平级气动性能影响的研究提供参考。As an important component of the secondary air system in gas turbines,rim seal can effectively prevent the gas ingestion.However,the excessive cooling air significantly affects the aerodynamic performance of turbine stage due to the coolant egress and mixing with the mainstream through rim seal.The flow characteristics of rim seal and aerodynamic performance of turbine stage was numerically investigated using three-dimensional unsteady Reynolds averaged Navier-Stokes(URANS)and shear stress transfer(SST)k-ωturbulence model.The numerical sealing effectiveness of rim seal is consistent with the experimental data.The accuracy of the employed numerical method is validated.The flow characteristics of the rim seal and aerodynamic performance of turbine stage is studied at three different coolant flow rates.The flow pattern in the stator-rotor cavity,gas ingestion and coolant egress characteristics are analyzed.The obtained results show that the inner cavity of the rim seal is completely sealed at three coolant flow rates.A lower coolant flow rate for the last stage can achieve a higher sealing effectiveness of rim seal.The average sealing effectiveness of the outer cavity rotor disk is 4.4%higher than that of the stator disk at the lowest coolant flow rate.For the last stage of turbine,externally-induced ingress caused by the uneven distribution of mainstream circumferential pressure is dominant and the pressure field near the leading edge of blades has a greater impact on gas ingestion than the pressure field at the wake of vanes.For every 1.0%increase in coolant mass flow ratio,the total-to-total efficiency of the turbine stage decreases by around 1.0%.The impact of cooling air outflow from the rim seal on the aerodynamic performance of downstream blades is greater.The flow direction of the egress lags behind the mainstream in the tangential direction,causing the mixed airflow to strike the leading edge of the suction surface of blades at a negative angle of attack,and increasing the pressure on the leading edge of t

关 键 词：燃气透平 轮缘密封 燃气入侵 气动性能 

分 类 号：TK474.7[动力工程及工程热物理—动力机械及工程]