Abstract: In order to improve the performance of the turbine rotor blade squealer tip, the effects of the rib structure on the vortex inside the tip clearance and the mechanism of reducing the heat transfer coefficient and aerodynamic loss are investigated. Effects of the rib layout on the heat transfer and aerodynamic performance of the turbine rotor blade squealer tip were numerically investigated using the three-dimensional Reynolds-Averaged Navier-Stokes (RANS) solution and k-ω turbulence model. Based on the GE-E³ turbine rotor blade squealer tip structure, four kinds of rib layouts of full rib layout, half rib layout connected with suction side, half rib layout connected with pressure side, and half rib layout in the rear squealer cavity along the camber line were designed in equal spacing. The numerical prediction heat transfer coefficient distribution was well agreement with the experimental data. The accuracy of the numerical method and turbulence model was validated. The obtained results show that the averaged heat transfer coefficients of the blade tip with the half rib layout in the rear squealer cavity decreases by 11.3%, 3.1%, 11.3% and 2.8% by comparison of the squealer tip without rib layout and with full rib layout, half rib layout connected with suction side, half rib layout connected with pressure side. The similar total pressure coefficient of the rotor blade with half rib layout connected with pressure side and half rib layout in the rear squealer cavity is obtained. The total pressure coefficient of rotor blade with half rib layout connected with pressure side and half rib layout in the rear squealer cavity reduces by 1.4%, 2.7% and 4.0% compared to the squealer tip without rib layout and with full rib layout, half rib layout connected with suction side. The rib layout can efficiently decrease the vortex strength in the squealer tip cavity and corresponding aerodynamic loss. In addition, the weaker strength vortex in the upstream squealer tip cavity enters into the downstream cavity through the half rib in the rear cavity. This flow behavior reduces the heat transfer coefficient of the rear region in the squealer tip. The squealer tip with the half rib layout in the rear squealer cavity shows the best aerothermal performance.

Key words: Turbine blade;Squealer tip;Rib layout;Heat transfer characteristics;Aerodynamic performance;Numerical simulation

摘要： 为提高凹槽状叶顶气热性能，探究肋条布局对凹槽状叶顶间隙腔室内旋涡的调控作用和降低传热系数与气动损失的作用机制，采用数值求解三维Reynolds-Averaged Navier-Stokes (RANS)方程和k-ω湍流模型的方法研究了肋条布局对涡轮动叶凹槽状叶顶传热和气动性能的影响。基于GE-E³涡轮级动叶凹槽状叶顶结构，在叶顶凹槽腔室内沿中弧线等间距设计了全肋条布局、吸力侧半肋条布局、压力侧半肋条结构和凹槽尾缘半肋条结构共4种肋条布局。数值模拟动叶叶顶传热系数分布与实验数据对比，验证了所采用的数值方法和湍流模型的有效性。结果表明：凹槽尾缘半肋条布局的叶顶平均传热系数比凹槽状叶顶结构、全肋条布局、吸力侧半肋条和压力侧半肋条布局分别低了11.3%，3.1%，11.3%和2.8%；压力侧半肋条布局与凹槽尾缘半肋条布局的动叶出口截面总压损失系数相近，比凹槽状叶顶结构、全肋条布局和吸力侧半肋条布局分别减小了1.4%，2.7%和4.0%。肋条布局能够有效降低凹槽状叶顶间隙腔室内的旋涡强度，减少叶片的气动损失；同时上游凹槽腔室强度较弱的旋涡通过凹槽尾缘半肋条布局进入下游凹槽腔室，降低了尾缘区域的传热系数。凹槽尾缘半肋条布局的动叶叶顶具有最佳的气热性能。

关键词: 涡轮动叶;凹槽状叶顶;肋条布局;传热特性;气动性能;数值模拟