In the secondary chamber of ducted rocket, there exists a relative speed between boron particles and air stream. Hence, the ignition\r\nlaws under static conditions cannot be simply applied to represent the actual ignition process of boron particles, and it is required\r\nto study the effect of forced convective on the ignition of boron particles. Preheating of boron particles in gas generator makes\r\nit possible to utilize the velocity difference between gas and particles in secondary chamber for removal of the liquid oxide layer\r\nwith the aid of Stoke�s forces. An ignition model of boron particles is formulated for the oxide layer removal by considering that it\r\nresults from a boundary layer stripping mechanism. The shearing action exerted by the high-speed flow causes a boundary layer\r\nto be formed in the surface of the liquid oxide layer, and the stripping away of this layer accounts for the accelerated ignition of\r\nboron particles. Compared with the King model, as the ignition model of boron particles is formulated for the oxide layer removal\r\nby considering that it results from a boundary layer stripping mechanism, the oxide layer thickness thins at all times during the\r\nparticle ignition and lower the ignition time.
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