燃气轮机封严倒角对气动和冷却性能影响的数值研究

Numerical Study on the Impact of Seal Chamfering on Aerodynamic and Cooling Performance of Gas Turbines

摘要: 燃气轮机封严气流起到防止主流入侵的作用，但同时对冷却效果造成一定的影响。为了评估封严结构、主要是封严出气边倒角的影响，本文采用数值模拟方法对燃气轮机叶栅流动进行了仿真，通过数值模拟，评价不同倒角对燃气轮机端区冷却效果的影响。方法：采用数值模拟的方法研究了不同的封严倒角对涡轮端区冷却性能的影响。基于雷诺平均法(RANS)以及标准k-ω湍流模型，分别设置封严倒角r为0~5 mm，以气膜冷却效率和气动损失为指标进行对比研究。结果：不带倒角结构的基础封严结构会使端区流体温度出现显著下降，并且产生漩涡，而以倒角半径r = 5 mm作为典例进行对比分析发现，增加倒角结构以后其冷却效果会提高，且端区涡量减小。冷却效率η随着倒角半径的增加而增加；选取总压损失系数ξ作为气动损失评判标准，随倒角半径增大，总压损失系数下降，在r = 5 mm时气动损失最小。结论：封严结果的改变对燃气轮机冷却效果具有一定的影响。

Abstract: The airflow in gas turbine seals serves to prevent the main flow intrusion but impacts cooling performance. This study uses numerical simulation to assess the impact of seal structure, specifically the chamfering at the seal exit, on the cooling effect in the end region of gas turbines. Through numerical simulation, the effects of different chamfer sizes on the cooling performance are evaluated. Methods: Numerical simulations were employed to investigate the influence of various seal chamfer sizes on the cooling performance in the turbine end region. The study was based on Reynolds-Averaged Navier-Stokes (RANS) equations and the standard k-ω turbulence model. Chamfer radii (ranging from 0 to 5 mm) were set, and multiple parameters were compared at 5% and 50% of the blade height. Results: The baseline seal structure without chamfering caused a significant drop in fluid temperature in the end region and generated vortices. Comparative analysis using a chamfer radius of r = 5 mm revealed that adding a chamfer improved the cooling effect and reduced the vorticity in the end region. Cooling efficiency (η) was chosen as the evaluation standard for cooling performance, and within the scope of this study, η increased with the chamfer radius. The total pressure loss coefficient (ξ), used to evaluate aerodynamic loss, decreased as the chamfer radius increased, with the lowest aerodynamic loss observed at r = 5 mm. Conclusion: Changes to the seal structure have a significant impact on the cooling performance of gas turbines.