微重力条件下热厚固体材料燃烧特性研究

In addition to fundamental understanding of combustion processes, burning behaviors of thermally-thick solid materials in microgravity are of practical importance for fire safety in manned spacecraft. Because of the limited opportunities to perform long-duration space experiments, few data exist for the burning of thick solids in microgravity, such that little is known about the combustion phenomena and the flame characteristics. In the present project, microgravity experimental data of the orbital experiment “Ignition and Burning of Thick Solid Materials in Microgravity”, which has been conduced aboard the SJ-10 satellite of China, will be analyzed in detail to provide significant information about the flame spread and extinction phenomena over thick fuels in low-velocity flow regime. The experimental results will be used also as a benchmark for the validation and improvement of the numerical models and the narrow channel apparatus, which can provide simulated microgravity conditions in a normal gravity laboratory. Furthermore, systematic experiments in the normal gravity narrow channel apparatus and in a microgravity drop tower facility will be conducted to acquire a comprehensive understanding of combustion processes, and the coupled effects of low-velocity flow, oxygen concentration, atmospheric pressure and thermal properties on the extinction limits, flame spread rates, and flame characters will be examined. At the same time, numerical simulations will be performed to study the combustion process and the flame behavior of thick solids in microgravity. The important roles of chemical kinetics, thermal radiation, and flame structures and their interactions will be discussed. A detailed analysis is expected to reveal the fundamental effects of different variable parameters, and to improve the understanding of underlying combustion mechanisms.

微重力环境中热厚固体材料的燃烧特性研究对于深入理解材料燃烧机理、预防载人航天器舱内火灾都具有重要意义。受空间实验机会的限制，现有微重力下热厚材料燃烧的实验数据十分有限，对燃烧规律和火焰特性的了解远不充分。本项目从“实践十号”科学实验卫星热厚非金属材料燃烧实验获得的空间实验数据出发，通过深入分析，认识低速流动中火焰传播和熄灭的基本规律，并对窄通道地面实验模拟方法和数值计算模型进行验证和完善；利用地面模拟实验和落塔实验，进一步研究低速流动、氧气浓度、环境压力和辐射特性等多参数耦合作用下火焰的熄灭极限、传播速度和火焰特征，全面掌握热厚材料燃烧的影响因素；同时，开展微重力下热厚材料燃烧过程和火焰特性的数值模拟分析，探讨化学反应动力学、热辐射、火焰结构等的相互作用，揭示不同因素影响火焰特性的规律和机理。

微重力条件下固体材料燃烧特性研究对于发展燃烧理论具有不可替代的作用，相关基础知识是保障载人航天器防火安全的重要基础，但已有对微重力下材料燃烧的研究主要集中在热薄材料，关于热厚材料的研究结果十分有限。本项目将“实践十号”科学实验卫星热厚非金属材料燃烧实验、窄通道地面模拟实验、落塔微重力实验和数值模拟等有机结合，对微重力环境中热厚材料燃烧进行了系统研究。主要研究内容包括空间实验数据分析、窄通道实验模拟方法和数值计算模型验证、环境压力和辐射特性等多参数耦合作用对热厚材料燃烧的影响等。研究结果揭示了微重力低速气体流动中热厚固体材料表面火焰传播与熄灭的规律，阐释了氧气浓度、材料性质和构型等因素对火焰特性的影响规律及微重力火焰传播和熄灭的控制机理；获得了气流速度、氧气浓度、环境压力和热辐射特性等参数耦合影响火焰传播速度和熄灭极限的定量数据，系统掌握它们对材料燃烧的影响机制，深化了对环境条件控制材料燃烧机理的认识；建立了一套用于模拟微重力下热厚材料燃烧特征的地面实验系统，优化了微重力下热厚材料燃烧过程的数值模拟方法，为进一步研究微重力固体材料燃烧问题提供了重要的基础条件。项目研究取得了预期的研究成果,促进了对热厚固体材料燃烧过程的深入理解，对载人航天器材料防火性能评价和材料筛选具有现实意义，也将为未来载人航天器舱内大气环境的选择和应对防火安全问题提供重要参考。