铝粉在高温水蒸气中点火与燃烧机理研究

As a fuel additive in some power engine, metal particles show its advantages of high density and high combustion enthalpy. In order to have a deeper understanding of the metal particles combustion process and provide a theoretical basis for using metal particles in the complex chemical conditions, study on combustion mechanism of aluminum power in steam atmosphere is proposed. Through the chemical shock tube experiment, the ignition and combustion characteristics of Al particles in high temperature water vapor were obtained in a wide range of parameters such as temperature and pressure, and the influencing factors were analyzed. To establish an Al/H2O ignition and combustion model，and analyze the combustion process of aluminum powder. Discusses the scope of application of the combustion model from diffusion-controlled combustion to chemical kinetics controls combustion. Analyze the influence law of the combustion characteristics of nanometer-sized aluminum powder, and emphasize the difference under different surface morphology of hydrocarbon coating and natural oxidation. The Al/H2/O2/N2 hybrid detonation phenomenon with relatively simple flow and significant Al/H2O reaction will be selected to further studied the reaction under the condition of macroscopic flow. In the hybrid detonation phenomenon, the Al powder is ignited by gas phase detonation, and the combustion of the al powder has an influence on the structure of the detonation wave. The hybrid detonation provides a relatively simple high-speed flow that can be simplified to a one-dimensional unsteady two-phase flow model to verify the ignition and combustion model of aluminum powder in steam.

金属粉末作为某些动力装置的燃料或添加剂，已展现其密度高、燃烧焓高的优势。为了更深刻的认识金属粉末的燃烧化学反应过程，在复杂条件下加以利用提供理论基础，提出开展高温水蒸气条件下铝粉点火与燃烧机理实验研究。开展化学激波管实验，在较宽的温度、压力等参数范围，获得Al颗粒在高温水蒸气中的点火和燃烧特性，并对影响因素进行分析。建立Al/H2O点火与燃烧模型，分析铝粉燃烧过程及路径，从扩散控制燃烧到化学动力学控制燃烧，讨论燃烧模型的适用范围。分析纳米铝粉的燃烧特性的影响规律，重点关注烃类包覆、自然氧化两种不同表面形态下纳米铝粉的点火与燃烧机理的区别。选取流动相对简单，存在Al/H2O反应显著的混合爆轰现象，进一步在有宏观流动情况下进行Al/H2O点火燃烧研究。混合爆轰现象中利用气相爆轰点燃铝粉，同时铝粉的燃烧又对爆轰波结构产生影响，可简化为一维非定常两相流模型，验证铝粉在水蒸气中点火燃烧模型。

铝粉作为某些动力装置的燃料或添加剂，已展现其密度高、燃烧焓高的优势。为了更深刻的认识金属粉末燃烧时的物理化学过程，也为在复杂反应条件下金属粉末的有效利用提供理论基础，高温水蒸气条件下铝粉点火与燃烧机理实验研究非常重要。本项目建立了Al/H2O化学激波管点火燃烧实验系统，通过激波管实验，总结归纳了温度、压力和氧化剂浓度等参数对水蒸气中铝粉的点火延时和燃烧时间的影响规律。对不同条件下，铝粉的点火与燃烧是处于反应动力学控制还是扩散控制，进行了辨识，给出了铝粉点火延时与燃烧时间拟合公式。设计并建设了Al/H2/O2/N2混合爆轰实验系统，开展了铝粉粒径1μm至50μm不同工况下的混合爆轰实验，实验结果体现了单波爆轰、双波爆轰等不同的混合爆轰波结构。分析了混合爆轰波现象，建立了一维定常的计算模型，对计算结果与实验结果进行分析，获得了铝粉颗粒的点火延迟对混合爆轰波结构的影响规律。