壁面结焦影响下的碳氢燃料管内流动换热特性研究

碳氢燃料作为发动机新型热防护技术中广泛采用的主动冷却介质，高温下引发的结焦问题会对其流动和吸热冷却过程产生复杂影响。本项目针对包括氧化结焦和裂解结焦的碳氢燃料壁面结焦形式，研究加热管内流动换热特性在结焦影响下发生的复杂变化过程。基于实验测量结果建立和验证所需的结焦速率预测模型；构建完整结焦过程和管内物理场的动态模拟数值计算方法和分析方法，澄清壁面结焦与流动换热间的耦合影响机制，定量评估结焦对流动换热特性的影响程度；基于结焦量的空间变化采取网格自适应，对管内存在结焦高峰的不同区域开展更为精细的模拟研究，分析特殊区域内结焦快速生长过程中物理场细节的动态变化和对局部流动换热特性的影响。期望通过本项研究形成对碳氢燃料在高温下的物理化学过程更为完整和深入的认识，为在发动机主动热防护系统设计体系中囊括结焦影响提供前沿性的技术储备和理论支持。

Hydrocarbon fuels has become the widely used coolant for the thermal protection techniques of engines. The appearance of coking at high temperatures exerts complicated impacts on the flow and convective cooling process of the hydrocarbon fuel. Focusing on the surface coking phenomena, including oxidative coking and pyrolytic coking, the complicated variation of the flow and heat transfer characteristics will be investigated. The required coking prediction models will be developed and validated, according to the results from experimental measurements. The dynamic simulation method and the analysis method for integral coking process will be established to clarify the coupling mechanisms between surface coking and convective heat transfer, and to quantitatively evaluate the effects of coking on flow and heat transfer characteristics. Based on the spatial change of the amount of coke, the mesh self-adaption will be employed for detailed simulation of the tube sections with coking peak. The changes of the physical fields and the local flow and heat transfer characteristics during the rapid growth of coking will be analyzed. This investigation is expected to be conducive to fundamentally understand the complicated physicochemical process of the hydrocarbon fuel at high temperature, which provides cutting-edge technical reserves and theoretical references for considering the impacts of coking in the design of the active thermal protection system of engines.