吸热型碳氢燃料流体动力学理论建立和实验验证

Endothermic hydrocarbon fuel is used as coolant in the regeneratively cooled scramjet. The Ledinegg instability and flow rate distribution are key problems in the small cooling passages distributed in the wall of the combustion chamber. The thermal-hydraulic theory for boiler clarifies that the multi-valued hydrodynamic characteristics represented by a cubic curve is the reason of the Ledinegg instability in two-phase fluid flow. Our preliminary study indicated that the instability for endothermic hydrocarbon fuel would became even worse to a quantic curve after pyrolysis. In this project, based on the frictional drag Darcy Law in the Flow Mechanics, the flow characteristics and 2-D flow regime of endothermic hydrocarbon fuel in the high heat flux mini-channels will be investigated. The flow pattern visualization and the near-wall two phase flow measurement method will be adopted to uncover the effect of heat flux on the flow resistance characteristics in the mini-channel with big temperature gradient along the radial direction. Based on the flow resistance characteristics, the calculated model for the multi-valued thermal-hydraulic characteristics will be developed, and then the thermal-hydraulic dynamic theory for endothermic hydrocarbon fuel will be constructed. In the experimental platform with electrically heated test section, which was built to replace the wind tune to form a practical thermal environment in the scramjet, the Ledinegg instability and flow rate distribution characteristics will be investigated in the heated parallel channels to verify the accuracy of the thermal-hydraulic dynamic theory for endothermic hydrocarbon fuel. The construction of the thermal-hydraulic dynamic theory for endothermic hydrocarbon fuel opens a new direction to investigate the fluid dynamics in the chemical reaction conditions, which is of great value for the scientific research and application.

吸热型碳氢燃料作为冷却剂，在超燃冲压发动机壁面微小槽道内的再生冷却过程，可能存在静态不稳定性，导致流量分配不均而冷却失效。锅炉水动力学理论阐明：水动力学多值性（三次曲线）是导致两相流动静态不稳定性的原因。我们前期研究发现：高温裂解反应加剧了不稳定性，使吸热型碳氢燃料的流体动力学多值性变成五次曲线。本项目在前期十多年的碳氢燃料流动传热、热物性测量、流体动力学定性研究的基础上，基于流体力学沿程阻力达西定律，采用流型可视化方法和近壁区两相流测试技术，研究高热流密度单通道内的二维流动机理和流阻特性，获得吸热型碳氢燃料的流体动力学多值性曲线计算模型，建立吸热型碳氢燃料流体动力学理论。在替代风洞的大功率电加热实验平台上，模拟发动机燃烧室壁面热环境，通过碳氢燃料在并联多通道内流量分配实验，验证该理论的正确性。碳氢燃料流体动力学理论的建立，为存在化学反应的流体动力学研究开创新的方向，具有重要的科学意义。

吸热型碳氢燃料作为冷却剂，在超燃冲压发动机壁面微小槽道内的再生冷却过程，存在静态不稳定性（Ledinegg instability）和流量分配不均的问题。锅炉热工水力学理论阐明：水动力学多值性（三次曲线）是导致两相流动静态不稳定性的原因。我们的前期研究发现：高温裂解反应加剧了不稳定性，使吸热型碳氢燃料的流体动力学多值性变成五次曲线。本项目基于流体力学沿程阻力达西定律，采用流型可视化方法和近壁区两相流测试技术，研究高热流密度单通道内的二维流动机理和流阻特性，获得吸热型碳氢燃料的流体动力学多值性曲线计算模型，建立吸热型碳氢燃料流体动力学理论。在替代风洞的大功率电加热实验平台上，模拟发动机燃烧室壁面热环境，通过碳氢燃料在并联多通道内流量分配实验验证该理论的正确性。吸热型碳氢燃料流体动力学理论的建立，为化学反应条件下的流体动力学研究开创新的方向，具有突出的科学意义和应用价值。