摘要
针对燃气入侵导致部件热疲劳和涡轮气热性能降低问题,提出了一种双重径向轮缘密封结构。采用数值求解三维非定常雷诺平均湍流模型(URANS)和SST k-ω湍流模型的方法,研究了4种封严冷气量下双重径向轮缘密封的时均封严效率和非定常流动特性,对燃气入侵和冷气出流特性进行了分析。研究表明:所提结构的内腔可以达到封严状态,外腔时均封严效率随封严冷气量的增加而增加;密封间隙内的非定常流动特性受较大Kelvin-Helmholtz不稳定旋涡影响,高温燃气直接冲击转盘壁面的过渡圆弧结构,并在该位置与冷气掺混形成顺时针旋涡阻止冷气出流,呈现左侧封严效率的高封严效率区和右侧的低封严效率区;受高动量封严冷气作用,入侵燃气向静盘侧偏移形成大尺度逆时针旋涡,进一步阻止燃气入侵。封严冷气流出后沿动叶端壁向下游流动,同时受叶栅通道旋涡卷吸作用逐渐脱离壁面,使得对端壁的冷却效果降低,在动叶尾缘处冷却效率降低至0.03以下。该研究为燃气透平双重径向轮缘密封的非定常燃气入侵和封严机理,以及封严冷气对下游端壁影响的研究提供了一定的参考。
In order to solve the problem of thermal fatigue of components and decrease of turbine aerothermal performance caused by gas ingestion,a double radial rim seal structure is proposed.The sealing efficiency and unsteady flow pattern of the rim seal at four kinds of sealing coolant flow rates are numerically investigated with three-dimensional unsteady Reynolds-averaged Navier-Stokes(URANS)and SST k-ωturbulence model solutions.The characteristics of gas ingestion and coolant egress are analyzed.The obtained results show that the inner cavity of the structure can be completely sealed,and the sealing efficiency of the outer cavity increases with the increase of the coolant flow rates.The larger Kelvin-Helmholtz unstable vortex influences the unsteady flow pattern in the seal clearance.The mainstream directly impinges on the arc structure connecting the disk cavity and blade surface,and mixes with the coolant.This flow behavior generates the clockwise vortex,and prevents the coolant egress,showing the high sealing efficiency area with on the left and the low sealing efficiency area with on the right.The large-scale anti-clockwise vortex is generated as the ingestion flow moves to the stator disk wall under the function of the high-momentum coolant along the rotor disk wall,which further prevents the gas ingestion.The coolant egress flows to the downstream along the blade endwall,and is gradually lifted off the endwall because of the entrainment of the passage vortex.As a result,the cooling effect on the endwall is reduced,and the cooling efficiency at the trailing edge of the blades is reduced to less than 0.03.The research provides reference for the unsteady gas ingestion and sealing mechanisms of the gas turbine double radial rim seal and the influence of sealing coolant on the downstream endwall.
作者
郭粲
白波
雷隆
李志刚
李军
GUO Can;BAI Bo;LEI Long;LI Zhigang;LI Jun(Institute of Turbomachinery,Xi’an Jiaotong University,Xi’an 710049,China)
出处
《西安交通大学学报》
EI
CAS
CSCD
北大核心
2024年第10期95-107,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-0011-0031)。
