附加分叉射流喷注对气膜孔冷却特性的影响

Film Cooling from a Row of Holes Supplemented withAdditional Branched Jet Injection

关键词:  气膜冷却  分叉射流喷注  反涡  冷却效率  传热

Key words:  Film cooling  Branched jet injection holes  Anti vortices  Cooling effectiveness  Heat transfer

摘要:

利用三维数值计算研究具有附加分叉射流喷注的单排气膜孔冷却结构的强化冷却特性,考察了三种形式的分叉孔结构和四个吹风比的影响。研究结果表明,主气膜孔附近射流喷注孔的存在能够诱导一对反涡,削弱缘于主气膜孔下游气膜出流和主流相互作用的肾形涡对,有利于提高气膜冷却效率,同时也增强了对流换热；当分叉射流喷注孔出口与主气膜孔在同一流向位置时,可以获得较高的气膜冷却效率和相对较低的对流换热系数增强比。 

Abstract:

Three-dimensional numerical simulation was conducted to investigate the enhanced cooling performance caused by addition of branched jet injection holes to the primary cylindrical film cooling holes. Three geometry of branched jet injection holes and four blowing ratios were considered.The results show that the presence of branched jet injection holes in the nearby region of the primary film cooling holes cause a pair of anti vortices mitigating the primary vortices due to mainstream-coolant jet interaction in the downstream region. These anti vortices provide an increment in the film cooling effectiveness and also enhance heat transfer coefficient over the baseline case. When the exit of branched jet injection holes is located inline with the primary film cooling holes, it gets a relative lower heat transfer coefficient ratio and a higher film cooling effectiveness.