抑涡孔气膜冷却的大涡模拟

采用大涡模拟研究抑涡孔气膜冷却的流动和换热机理.通过与相同工况下圆孔气膜冷却流场的湍流结构进行比较分析,得出辅孔射流与主孔射流之间的干涉作用,并探索大尺度湍流结构影响气膜冷却效率的物理机制.结果表明：①辅孔射流抑制主孔射流形成的反转涡对的尺寸和强度,并为主孔射流的卷吸提供冷气补充;②由于上游辅孔出流冷气的保护作用以及对主孔出口尾缘低压区的冷气补充作用,主孔射流在气膜孔出口处温度没有急剧升高;③由于辅孔射流的干涉作用,主孔射流并未形成完整的发卡涡结构,而是无规律的近壁条带结构,减少了冷气和主流的掺混,并使冷气更好覆盖和冷却壁面.

Large eddy simulation of anti-vortex film cooling

Large eddy simulation was used to investigate the fluid flow and heat transfer mechanism of anti-vortex film cooling. The interaction between the main hole and the side holes was obtained, and the mechanism that turbulence structures affected film cooling effectiveness was analyzed by comparing with standard round hole case for the same blowing rate. It is found that the presence of side hole jets decrease the size and strength of the counter-rotating vortex pair of the main hole jet, and supply coolant for its entrainment. The temperature of the main hole jet does not rise sharply at the exit of the main hole because the side hole jets supply to the low-pressure area behind the exit of the main hole. Due to the side hole jets' effect, the main hole jet does not form whole hairpin structures but near-wall streaks, decreasing its mixing with the main hot stream and enabling the coolant to cover and cool down the wall better.