Method for reducing the nonsteady side loads acting on a nozzle of a rocket engine

A method for reducing the nonsteady side loads acting on a nozzle of a rocket engine during a startup phase of said engine, said nozzle comprising a combustion chamber where exhaust gases are generated, a divergent portion in which a supersonic flow of said exhaust gases occurs, and a throat connecting said combustion chamber to said divergent portion, which method comprises axially positioning a body along the divergent portion's axis for perturbing the flow of the exhaust gases inside the divergent portion such that said body does not form a secondary throat of the nozzle and that, during at least a fraction of said startup phase in which the stagnation pressure of the exhaust gases increases gradually, a shock wave, induced by the disturbance of the flow of the exhaust gases by said body is incident to the wall of said divergent portion at an axial incidence position where it produces a jet separation or a separation in the form of a toroidal separation bulb.