不同温区下横肋通道超临界碳氢燃料流动和换热数值研究

Numerical Study on Flow and Heat Transfer of Supercritical Hydrocarbon Fuel in a Transverse-Rib Channel under Different Temperature Regions

关键词:  超临界燃油  横向肋  流动传热  综合性能  数值模拟

Key words:  Supercritical hydrocarbon fuel  Transverse rib  Flow and heat transfer  Comprehensive performance  Numerical simulation

摘要:

为了研究方形通道内超临界碳氢燃料在不同温区下的流动换热特性，采用数值模拟方法对比分析了三种横向肋结构的作用效果。研究结果表明，超临界碳氢燃料热物性随温度的强依变性对近壁区流动的热对流能力和湍流强度影响显著，在光滑通道中的平均对流换热系数随进口温度的增加呈现出先降低（从亚临界温区向跨临界温区）后升高（从跨临界温区向超临界温区）的变化趋势；与光滑通道相比，带肋表面平均对流换热系数随超临界碳氢燃料进口温度的变化趋势与光滑表面存在明显的差异，呈现出较为复杂的变化规律；从对流换热增强和流动损失的综合效果进行评价，带肋结构在亚临界和跨临界温区的综合性能因子大于1，在所研究的三种横向肋结构中，交错肋是一种较为理想的横向肋布局形式。

Abstract:

In order to study the flow heat transfer characteristics of supercritical hydrocarbon fuel in square channel at different temperature regions，a numerical investigation is performed to evaluate the roles of transverse rib configurations （including continuous， interrupted and staggered ribs）. The results indicate that the strongly temperature-dependent thermophysical properties of supercritical hydrocarbon fuel affect the thermal convection capacity and turbulent intensity significantly in the near-wall flow field. For the smooth channel， the averaged convective heat transfer coefficient on the heated surface firstly decreased from the sub-critical temperature region to the transcritical temperature region and then increased from the transcritical temperature region to the super-critical temperature region， with the increase of the inlet temperature of supercritical hydrocarbon fuel. When compared to the smooth channel， on the ribbed surface the variation trend of averaged convective heat transfer coefficient with the inlet temperature of supercritical hydrocarbon fuel becomes more complicated. In the view of a comprehensive factor that considers both the heat transfer enhancement and flow loss together， it is confirmed that the ribber schemes always play an active role when the supercritical hydrocarbon fuel works in sub-critical and transcritical temperature regions. Among the current three transverse rib configurations， the staggered layout of ribs is suggested to be a more promising scheme.