船舶燃气轮机U型肋通道的颗粒沉积特性研究

Particle Deposition Characteristics of U-Shaped Rib Channel of Marine Gas Turbine

关键词:  船舶燃气轮机  肋倾角  气膜孔  颗粒沉积  沉积模型

Key words:  Marine gas turbine  Rib inclination  Film cooling hole  Particle deposition  Deposition model

摘要:

为了探究船舶燃气轮机内部冷却通道的颗粒沉积特性，本研究以分析从随压气机抽取的气体进入涡轮内部冷却通道内的颗粒动力学特性及颗粒与壁面相互作用的特性出发，基于高温壁面建立速度场影响的沉积模型，利用用户自定义函数实现沉积模型与CFD程序的嵌套。并简化船舶燃气轮机涡轮内部冷却通道，选取了在气膜孔与壁面之间夹角β=90°时，下游肋倾角α不同（α=30°，45°，60°，75°，90°），及在下游肋倾角α=60°时，气膜孔与壁面之间夹角β不同（β=30°，45°，60°，75°，90°）的八种不同内冷结构进行数值计算。研究表明，在β=90°不变时，随着α=90°减小到α=30°，弯头壁面换热性能和沉积率逐渐呈下降趋势，下游肋与肋之间壁面上颗粒的撞击率逐渐上升。α=60°，β=45°的U型肋通道，是八个内冷结构中弯头壁面沉积率最少、换热性能最好、能够有效减少内部冷却通道颗粒沉积和改善船舶燃气轮机涡轮海洋环境工作适应性的内冷结构。

Abstract:

In order to explore the deposition characteristics of marine gas turbine internal cooling channel， based on the particle dynamics characteristics and interaction characteristics between particle and wall of the gas extracted from the compressor into cooling channel of the cooling turbine， a deposition model is established based on the high temperature wall under the consideration of flow field， and the user-defined function is used to realize the couple of deposition model and CFD program. The internal cooling channel of marine gas turbine is simplified. Eight kinds of internal cooling structures with different downstream rib angles （α=30°， 45°， 60°， 75° and 90° ） are selected when the angle between the film cooling hole and the wall is 90° and the downstream rib angle α is 60° with different roles between the film cooling hole and the wall （β=30°， 45°， 60°， 75° and 90° ）.The results show that when β=90° is constant， with α=90° reduced to α=30°， the heat transfer performance and the deposition rate of the elbow wall gradually decrease， and the impact rate of particles on the wall between downstream ribs gradually increases. The U-shaped channel with α=60° and β=45° has the least deposition rate and the best heat transfer performance among the eight internal cooling structures. It also can effectively reduce the particle deposition in the internal cooling channel and improve the marine environment adaptability of air-cooled turbine for marine gas turbine.