带气膜孔内部冷却通道的流动传热特性

Aero-and Thermodaynamic Features of the Flow Fields in the Internal Cooling Channels with Film Cooling Holes

燃气轮机高温透平内部冷却通道中弯头、肋片和气膜孔之间存在着复杂的交互作用。本文采用瞬态液晶技术对光滑通道、无抽吸的带肋通道和有气膜孔抽吸的带肋通道的表面传热分布和沿程压力损失进行了详细测量,同时采用RANS数值模拟方法研究其流场特性。结果表明180°弯头产生的大分离是压力损失的主要因素,45°斜肋片产生的螺旋形流动在弯头与大分离交互作用明显,气膜孔抽吸破坏孔附近边界层使得肋间传热而相对集中于孔附近。在13%抽吸量条件下,气膜孔抽吸降低U型通道中压力损失约20%,同时保持传热强化程度与无抽吸工况相同。

Interaction among bends, ribs and film cooling holes exists in the internal cooling channel in the gas turbines. The transient liquid crystal technology was used to measure the heat transfer distribution in a smooth channel, a rib-roughed channel and a rib-roughed channel with film cooling holes. The RANS simulation method was also applied to study the interaction of ribs, bends and film cooling holes. The results showed the 180 degree bend caused large separation in the downstream where dissipation and impingement caused great pressure loss. The helical flow filed caused by the 45 degree ribs became chaotic in the bend with great separation. The film cooling holes sucked the boundary layer near the holes and focused the high heat transfer region. In the U channel, the 13% suction air reduced the pressure loss by 20% while keeping the same heat transfer enhancement as the condition without suction, which is good for the internal cooling design.