层板冷却结构强化换热机理

Numerical Investigation on Mechanism of Heat Transfer Augmentation in Lamilloy

应用简化的换热模型分析了影响层板冷却效果的因素,得出了燃气侧气膜冷却效率ηf,层板内部换热效率ηi和参数f是影响冷效的决定因素。为了研究层板强化换热机理,提高其内部换热效率ηi以优化层板传热设计,本文在相同的两侧换热条件和冷气密流下,对5种相同孔径、通道高度和开孔率,不同内部绕流形式的层板结构和1种双层壁结构进行了流固耦合传热计算,得到了其综合冷却效率。结果表明层板结构的综合冷却效率明显高于双层壁;冷气沿程吸热焓增带走了大部分从燃气侧进入层板的热,并且冷气与层板内表面的换热主要发生在出气板上,扰流柱的存在增加了换热面积,一定程度上增强了换热;合理设计绕流结构有利于改善层板的热均匀性。

A simplified heat transfer model was used to analyze Lamilloy cooling characteristics. The results show that the parameter f, adiabatic effectiveness of film cooling at gas side and the internal heat transfer efficiency are important parameters in the design optimization. In order to learn how the internal flow patterns affect the overall cooling effectiveness of Lamilloy, conjugate numerical simulation were carried out for a double wall without pin fin and five Lamilloy cooling configurations with the same hole diameter, spacing and pin fin height. The numerical results show that Lamilloy has higher cooling effectiveness than the double wall. The coolant through the walls took off most of the heat, transferred from hot gas to the Lamilloy, and the heat transfer on internal surface of outlet plate was the major mechanism to remove the heat. The existence of pin fin increases heat transfer area and the amount of heat transfer in Lamilloy, and the uniformity of temperature in Lamilloy can be improved by proper design of pin fin.