To investigate the ignition and combustion mechanisms of boron agglomerates in oxygen-free steam for water ramjet applications, a laser ignition single-particle experimental system was established. The combustion process was found to comprise four sequential stages: preheating and structural loosening, molten collapse, micro-explosion combustion, and quasi-steady combustion. The results indicate that steam can act as an oxidizer to support vigorous boron combustion. Its unique chemical role (reacting with B2O3 to form volatile HBO2) effectively accelerates the removal of the surface oxide layer, resulting in a relatively thin molten shell. Entrapped steam continuously reacts with internal boron, generating gaseous products (H2, etc.) that trigger a distinct micro-explosion mode characterized by sustained ejection rather than the expansion-dominated behavior observed in air. Kinetic analysis reveals that the quasi-steady combustion stage is diffusion-controlled, with a burning rate constant comparable to that in air. A quantitative evaluation based on volume change yields a final combustion efficiency of approximately 39.1% in pure steam. These single-particle-level observations provide essential experimental evidence for understanding boron combustion mechanisms and for designing boron-based water-reactive fuel systems.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |