The combustion characteristics of single boron particle in forced convective flow in ramjet engines are investigated systemically. A physical and mathematical model is proposed taking into consideration the gas flow around the particle, the gas diffusion and the surface finite reaction dynamics. The two-dimensional axi-symmetric Navier-Stokes equations with species reactions are solved using the finite volume technique. And the numerical simulation method is validated. Then influencing factors such as the free stream velocity, particle radius, the ambient oxygen mass fraction and the ambient pressure on the combustion characteristics of single boron particle are studied by numerical simulations. And the effect mechanism for each factor is analyzed in detail. The numerical prediction results show that in forced convective flow, both the mass rate and the mass flux of the buring boron particle increase with the increase in the free stream velocity, the particle radius, the ambient oxygen mass fraction and the ambient pressure. A comprehensive analysis of the results is conducted and it is found that the mass flux of the buring boron increases with the stream Reynolds number. Then the mass flux of the buring boron particle in the static atmosphere is modified based on abundant numerical results to describe the combustion characteristics of the boron particle in forced convective flow.
 Fry R S. A century of ramjet propulsion technology evolution[J]. Journal of Propulsion and Power, 2004, 20(1): 27-58. King M K. Ignition and combustion of boron particles and clouds[J]. Journal of Spacecraft, 1982, 19(4): 294-306. Li S C. Experimental and theoretical studies of ignition and combustion of boron particles in wet and dry atmospheres[D]. Princeton: Princeton University, 1990. King M K. Modeling of single particle boron combustion[C]//19th JANNAF Combustion Meeting, 1982: 43-58. Golovko V V, Vovchuk Y I, Polishchuk D I. Combustion of single particles of boron in chlorine[J]. Combustion, Explosion, and Shock Waves, 1981, 17(5): 521-524. Ulas A, Kuo K K, Gotzmer C. Ignition and combustion of boron particles in fluorine-containing environments[J]. Combustion and Flame, 2001, 127(1-2): 1935-1957. Zhou W. Numerical study of muti-phase combustion: ignition and combustion of an isolated boron particle in fluorinated environments[D]. Princeton: Princeton University, 1998. Wang N F, Guan D L, Fan H J. Development of boron particles ignition and combustion[J]. Chinese Journal of Energetic Materials, 2001, 9(2): 86-89 (in Chinese). 王宁飞, 关大林, 范红杰. 硼颗粒点火和燃烧研究进展[J]. 含能材料, 2001, 9(2): 86-89. Mao C L, Li B X, Hu S Q, et al. Overview of models of boron particle ignition in hot air[J]. Journal of Propulsion Technology, 2001, 22(1): 6-9 (in Chinese). 毛成立, 李葆萱, 胡松启, 等. 热空气中硼粒子点火模型研究综述[J]. 推进技术, 2001, 22(1): 6-9. Hu J X, Xia Z X, Wang D Q. Study on burning rate of boron particles in secondary chamber of ducted rocket under forced convection conditions[J]. Journal of Solid Rocket Technology, 2007, 30(1): 21. Hussmann B, Pfitzner M. Extended combustion model for single boron particles—Part I: Theory[J]. Combustion and Flame, 2010, 157(4): 803-821. Hussmann B, Pfitzner M. Extended combustion model for single boron particles—Part II: Validation[J]. Combustion and Flame, 2010, 157(4): 822-833. Pope D N. Numerical simulation of convective fuel droplet vaporization and combustion in a low pressure zero-gravity environment[D]. Lincoln: University of Nebraska, 2001. Reid R C, Prausnitz J M, Poling B E. In the properties of gases and liquids[M]. New York: McGraw Hill, 1987: 256-364. Malcolm W C, Jr. NIST-JANNAF thermo chemical tables, Parts I and Ⅱ[M]. 4th ed. New York: American Chemical Society and American Institute of Physics, 1998: 270-1621. Makino A, Umehara N. Combustion rates of graphite rods in the forward stagnation field of the high-temperature, humid airflow[J]. Proceedings of the Combustion Institute, 2007, 31(2): 1873-1880. Tao W Q. Numerical heat transfer[M]. 2nd ed. Beijing: Higher Education Press, 2001: 90 (in Chinese). 陶文铨. 数值传热学[M]. 2版. 北京: 高等教育出版社, 2001: 90.