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利用热天平与激光点火装置,研究了不同气流速度下硼颗粒的热氧化特性和点火燃烧特性,在此基础上分析了对流换热对其影响规律。研究结果表明,气流速度对硼氧化反应的作用主要体现在对流换热项及扩散控制项两方面。气流速度对硼颗粒的点火燃烧过程的影响是双方面的。在流速较低时,其增大将促进硼颗粒的点火和燃烧,此时起主导作用的是氧扩散过程。随着流速的增加,对流换热对硼氧化反应的影响逐渐体现,超过某一程度后,其增大则不利于硼颗粒的点火和燃烧。研究还发现,硼颗粒的燃烧效率随气流速度的增大而增大,推测硼颗粒的燃烧效率的主要影响因素是氧扩散过程。
Thermal balance and laser ignition were used to study the thermal oxidation characteristics and ignition combustion characteristics of boron particles at different air velocities. On the basis of this, the influence of convection heat transfer was analyzed. The results show that the effect of gas velocity on the boron oxidation reaction is mainly reflected in the convection heat transfer and diffusion control terms. The effects of airflow velocity on ignition and combustion of boron particles are twofold. At low flow rates, the increase of boron accelerates the ignition and combustion of boron particles, which is dominated by the oxygen diffusion process. With the increase of flow rate, the influence of convective heat transfer on the oxidation reaction of boron gradually shows. When it exceeds a certain degree, the increase is not conducive to the ignition and combustion of boron particles. The study also found that the combustion efficiency of boron particles increases with the increase of air velocity, and the main factor that predicts the combustion efficiency of boron particles is the oxygen diffusion process.