基于CFD-DEM微细带肋内冷通道中颗粒沉积特性比较研究

Comparative Study of Particle Deposition Characteristics in a Miniature Ribbed Internal Cooling Channel based on CFD-DEM

航空发动机全天候全域长航时运行时,颗粒随着二次流空气系统进入到涡轮叶片内部,沉积堵塞在涡轮叶片内冷通道中,严重影响了涡轮叶片的冷却性能。本文采用计算流体力学和离散单元法(CFD-DEM)相结合的方法研究了涡轮叶片带肋细小矩形内冷通道中微尘颗粒的流动和沉积特性。所研究的内冷通道肋片周期性布置在通道的一侧,肋片阻塞比和肋间距比分别为0.024和10,考虑了平行直肋、45°斜肋和45°V肋3种肋结构,详细分析了雷诺数、颗粒斯托克斯数、入口颗粒体积分数和肋片的类型对颗粒流动和沉积特性的影响规律。结果表明:颗粒沉积主要发生在第1根肋片的前缘处;颗粒的沉积质量均随着雷诺数、斯托克斯数和颗粒体积分数增加而减小;在所有的肋片类型中,直肋布置时颗粒沉积现象最明显,其次是V肋,斜肋拥有最小的颗粒沉积质量。

When operating aero-engines under all-weather,all-region and long endurance conditions,particles enter the internal parts of turbine blades through the secondary flow air system.These particles deposite and block the internal cooling air system of gas turbines,significantly impeding the cooling performance of the turbine blades.A combination of computational fluid dynamics and discrete element method(CFD-DEM)was used to investigate the flow and deposition characteristics of fine dust particles in a miniature ribbed rectangular internal cooling channel of a turbine blade.The ribs were periodically arranged on one side of the channel,with a rib blockage ratio of 0.024 and a rib spacing ratio of 10.Three rib structures,such as transverse rib,45°inclined rib,45°V-shaped rib were analyzed.The effect of Reynolds number,Stokes number,inlet particle volume fraction and rib layout on the particle flow and deposite characteristics was studied.Results show that particle deposition occurs mainly at the leading edge of the first rib;the deposited mass of the particles all decrease with increasing Reynolds number,Stokes number and particle volume fraction;in all different rib layouts,the transverse rib exhibits the highest deposition mass,followed by the V-shaped rib,while the inclined rib has the lowest deposition mass.