Abstract: To study the influence of annular cavity of gas-ejection launcher on secondary combustion, RNG k-ε turbulence model, finite-rate/dissipation model and dynamic mesh update method are adopted to establish a secondary combustion model of initial cavity, in which the movement of rear cover is considered. Compared with experimental result of ejection launcher without annular cavity, the variation in fluid structure, ejection interior ballistics and variation in load are studied for the initial cavity with/without annular cavity and the initial cavity with different opening directions. The mechanism of that annular cavity reduces the secondary combustion impact is analyzed. Results show that, from the point view of fluid structure, an annular cavity can is added to change the direction of gas diffusion and decrease the area between gas and air. The backflow region with annular cavity can decrease the pressure peak caused by secondary combustion. From the point view of interior ballistics, the acceleration of missile in which the annular cavity opening is formed upwardly changes gently, the velocity out of tube is reduced by 5.9%, and the time out of tube is delayed by 4.5%.

Key words: ordnance science and technology, gas-ejection, secondary combustion, dynamic mesh motion, initial cavity, annular cavity