超临界压力下正癸烷在水平矩形冷却通道内的流动传热数值模拟

Numerical simulation of heat transfer of n-decane under supercritical pressure in horizontal rectangular cooling channels

为了研究浮升力效应对超燃冲压发动机燃烧室不同位置冷却通道传热特性的影响,对超临界压力下正癸烷在水平矩形冷却通道内的流动传热-固体导热耦合过程展开了详细的数值模拟研究。重点考察了燃烧室不同位置的冷却通道中浮升力对温度以及热流分配的影响及其机理。结果表明:由浮升力引起的二次流动使燃烧室不同位置的冷却通道温度分布和热流分配呈现显著的差异;浮升力提升了燃烧室不同位置冷却通道的换热效果,其中受热方向和重力作用方向相同的冷却通道换热性能提升得最多;修正的Jackson&Hall经验公式不能预测浮升力对冷却通道壁面对流换热的影响,需要寻找其他的经验公式或使用CFD手段进行计算分析来解决这一问题。

In order to examine the effect of buoyancy on conjugate heat transfer of hydrocarbon fuel flowing in horizontal rec- tangular scramjet-engine cooling channels at different locations,a numerical simulation of conjugate heat transfer of n-decane under supercritical pressure is carried out.The influence and its mechanism of buoyancy on temperature and wall heat flux distribution in cooling channels at different locations are emphatically discussed and analyzed.Results indicate that the secondary flow caused by buoyancy has a significant impact on the distribution of temperature and wall heat flux in cooling channels at different locations.Buoyancy enhances the heat transfer capacity of n-decane flowing in rectangular engine cooling channels,and the heat transfer performance of n-decane in the cooling channels with the same heating direction and direction of gravity is improved the most.The modified Jackson &Hall empirical heat transfer expression is not applicable for heat transfer prediction of n-decane at supercritical pressures with consideration of buoyancy effect and therefore it is necessary to find other empirical formulas or to use the CFD method to solve this problem.