矩形通道内超临界航空煤油非均匀传热与热裂解耦合机理研究

Regenerative cooling using onboard hydrocarbons (e.g., aviation kerosene) as coolant is an effective way to solve the thermal protection problem of scramjet. When the cooling channel is heated asymmetrically, the heat convection of aviation kerosene close to the inside wall of channel show significant heterogeneity. Especially when thermal cracking is accompanied, the multiphase, non-uniform heat transfer result from cracking products becomes more complex, and the coupling of heat convection and thermal cracking becomes more evident. Based on rectangular channel, this project plans to investigate the non-uniform heat transfer characteristics of aviation kerosene under supercritical pressure, thermal cracking kinetics of supercritical kerosene, and the coupling effect of non-uniform heat convection and thermal cracking within complex heat transfer. The project plans to discover the axial/radial non-uniform heat transfer pattern, the mechanism of heat transfer enhancement/ deterioration and the critical condition of heat transfer enhancement/ deterioration, the transformation pattern of cracking degree, chemical heat sink and cracking products on temperature, the acting mechanism of cracking products and heat sink on the complex multiphase flow heat transfer, and the acting mechanism of change of heat transfer pattern on the thermal cracking process. Key scientific issues to be resolved of this project are: the non-uniform heat transfer mechanism of aviation kerosene under supercritical pressure, the coupling mechanism of multiphase, non-uniform heat convection and thermal cracking inside the channel when thermal cracking is accompanied, and thermal cracking kinetic characteristics and modeling of kinetics of aviation kerosene under supercritical pressure.

采用机载碳氢燃料（如航空煤油）作为冷却剂的再生冷却是解决超燃冲压发动机热防护的有效方法。再生冷却通道非对称受热时，通道内超临界压力航空煤油对流换热具有显著的非均匀性，尤其是在热裂解伴随发生时，由热裂解产物导致的多相流非均匀换热问题更加复杂，对流换热与热裂解耦合作用的特征非常突出。本项目基于矩形通道，拟研究超临界压力航空煤油的非均匀对流换热特性、热裂解的动力学特性、对流换热与热裂解的耦合作用及复杂换热问题。探索通道内沿轴向/周向非均匀换热规律、传热强化/恶化机理及传热恶化临界条件；裂解度、化学热沉、裂解产物等随温度的变化规律；裂解产物及裂解热沉对复杂多相流换热的作用机制，以及热裂解发生时换热模式改变对热裂解的反作用机制。拟解决的关键科学问题是：通道内超临界压力航空煤油非均匀对流换热机理及热裂解伴随发生时多相流非均匀换热与热裂解的耦合机理、超临界压力航空煤油热裂解动力学特性及动力学模型的建立。

采用机载碳氢燃料（如航空煤油）作为冷却剂的再生冷却是解决超燃冲压发动机热防护的有效方法。燃料在升温过程中经历由压缩液态向超临界态及气态（热裂解）的转变，受拟临界区流体热物性剧烈变化和热裂解反应的影响，其在冷却通道内的流动换热规律十分复杂，流动-传热-热裂解间的耦合作用非常突出。面向超燃冲压发动机再生冷却技术应用环境，针对再生冷却通道内超临界压力航空煤油的复杂流动传热特性与机理问题，本项目开展了系统性的研究工作：揭示了超临界压力碳氢燃料传热强化/恶化及流动不稳定机理，建立了不稳定边界、临界热负荷及Nusselt数预测关系式；获得了超临界压力下裂解度、化学热沉及裂解产物随温度的变化规律，建立了热裂解反应动力学模型，揭示了裂解产物及化学热沉释放对于传热的作用机制；发展了超临界压力碳氢燃料-固壁耦合传热数值计算方法；探究了矩形通道内超临界压力航空煤油的流动阻力和对流传热特性；揭示了单侧加热矩形通道内的非均匀流动传热特性和流动-传热-热裂解的相互作用机制。本项目研究发展了再生冷却技术应用的理论基础，为再生冷却系统的合理设计提供了理论支撑。累计发表SCI论文8篇（JCR一区6篇），EI论文10篇，会议论文8篇。培养博士研究生3名，硕士研究生4名。