带起始气膜的大弯管发散冷却特性的数值研究

Numerical Investigation on Effusion Cooling Characteristics of Concave Wall Combined with Initial Film Cooling

关键词:  回流燃烧室  发散冷却  大弯管  综合冷却效率  数值模拟

Key words:  Reversed-flow combustor  Effusion cooling  Concave wall  Overall cooling efficiency  Numerical simulation

摘要:

针对带起始气膜的大弯管发散冷却特性开展了三维数值模拟，对有无起始气膜的大弯管发散冷却结构进行了对比分析，并开展了主流速度、开孔率等参数对带起始气膜的大弯管发散冷却特性的影响研究。结果表明：带起始气膜的大弯管发散冷却结构能有效地改善无起始气膜的大弯管发散冷却结构前端冷效低的缺点，显著提高了大弯管整体的温度分布均匀性，平均综合冷却效率可提升10.8%~15.4%；主流速度的增大会增强主流与大弯管壁面的对流换热，引起壁面温度升高；开孔率的增加使得大弯管整体的综合冷却效率呈上升趋势，单位面积冷气流量的增加减小了开孔率变化带来的差异。

Abstract:

3D numerical simulation was carried out to study the effusion cooling performance of the concave wall combined with the film cooling. The effusion cooling performances of the concave wall were compared between the structures with and without film cooling. Different mainstream velocities， open-area ratios were studied to reveal the characteristics of film cooling efficiency of the concave wall. The results show that the structure of the concave wall with film cooling is good at improving the overall cooling effectiveness in the front zone of the concave wall and also reducing the overall temperature gradient of the concave. There is an increase of 10.8%~15.4% in the averaged overall cooling effectiveness. The increase of the mainstream velocity augment the convective heat transfer between the hot gas and the concave wall and cause the temperature of the concave wall to rise. The overall cooling efficiency of the concave wall is improved by the increasing open-area ratio. The increase of the cooling flow rate reduces the difference caused by the open-area ratio.