US Patent 7823376 Thrust augmentation in plug nozzles and expansion-deflection nozzles

Thrust augmentation in a rocket nozzle is achieved by incorporating injectors for the introduction of unburnt fuel and oxidizer into a nozzle to combust in the nozzle and thereby supplement the primary thrust that is supplied by fuel and oxidizer that are combusted prior to entry into the nozzle. These secondary injectors are incorporated into the design of expansion-deflection nozzles and plug nozzles. In expansion-deflection nozzles, the injectors are either in the flow deflector itself or in the wall of the divergent section of the nozzle. In plug nozzles, the injectors are either in a shell of the nozzle surrounding the forward end of the centerbody or in the centerbody itself.