微重力实验环境可用于去除火焰中的浮力热对流以及浮力驱动的流体不稳定性现象, 对于理解射流火焰中流体与化学反应动力学的交互作用具有重要的指导意义。在化学反应动力学特征时间较长而与流体特征时间发生竞争的问题上, 通过微重力射流火焰结构以及瞬态行为能够揭示火焰在极限条件下的基础物理, 并为理论发展提供验证数据。该文围绕国内外具有代表性的微重力气体射流火焰地基和天基的实验内容, 从射流火焰的微重力实验方法、类比微重力的实验、火焰结构、碳烟生成、辐射热损失与熄灭、极限现象、火焰向湍流转捩、不同物理场对火焰影响等方面进行了回顾。结合中国空间站对于微重力射流火焰系列实验的规划, 为进一步凝练科学问题和难点问题提供参考。

Significance: By eliminating buoyancy-driven convection and flow instabilities, microgravity jet flame experiments provide a unique platform to study fluid-chemistry interaction. When the characteristic chemical time scale is sufficiently long and comparable to the fluid dynamic time scale, the structure and transient behavior of microgravity jet flames offer valuable insights into fundamental combustion physics under near-limit conditions. These experimental data are crucial for validating theoretical models. Progress: This paper reviews key microgravity jet flame experiments conducted worldwide, including both ground-based and space-based studies. The topics covered include experimental methods for investigating microgravity jet flames, simulated experiments, flame structure, soot formation, radiative heat loss and extinction, limit phenomena, flame transition into turbulence, effects of varying physical fields, flame-based particle synthesis, and diagnostic techniques for microgravity flames. Despite the progress, many dynamic phenomena associated with microgravity gas flame are out of the scope of this paper. These phenomena often stem from the balance between combustion-generated heat and radiative heat loss or interactions involving diffusion and fluid dynamics. Microgravity provides an ideal environment with controllable flow fields, allowing researchers to study these weak interactions, especially in the context of weak reaction systems operating far from the mixing ratio of equivalent ratios. The study of flame dynamics under microgravity remains an important way to develop corresponding theories. Conclusions and Prospects: Looking ahead, the study of microgravity jet diffusion flames, as reviewed in this paper, identifies several key research areas. From the perspective of near-limit chemical reactions, there is a need for more experiments involving weak flames under microgravity conditions. From the perspective of fluid and combustion transition, understanding the shift from laminar to turbulent flow is critical, as this fluid transition directly affects flame behavior. From the perspective of soot and radiation, the reaction kinetics of soot precursors and the physical processes that follow soot nucleation require more concise and accurate models. Current radiation heat transfer models face challenges in accurately predicting the behavior of macromolecular fuels and their derivatives, especially in high-pressure microgravity flame experiments where experimental data are more scarce. Improved radiation models must account for the unique radiation characteristics of fuel components, even at a high computational cost. Regarding the interaction between sound fields and microgravity flames, further research should explore the relationship between near-limit flames and fluid. Existing studies on microgravity premixed flames have used sound fields as a source of fluid disturbance. For near-limit diffusion flames, it is necessary to essential to evaluate the theoretical and modeling implications of traditional experimental approaches, such as standing waves and fluid instabilities. With ongoing investigations, including microgravity jet flame experiments aboard the China Space Station, this paper can be used to further consolidate scientific and challenging problems in the area.