System for controlling speed transition and thrust vectorisation in a multiple-shaped nozzle by secondary injection

A divergent section comprising multiple curved contours for a propulsion nozzle of an engine for aircraft or spacecraft propelled by chemical reaction, the propulsion nozzle being a nozzle having rotational symmetry about an axis, the engine comprising a reaction chamber producing propulsion gases intended to be ejected outside the propulsion nozzle in a mainstream, the divergent section comprising a nozzle throat, the divergent section further comprising:

• a first portion comprising a first wall connecting the nozzle throat to a connecting zone, said first wall having a first surface of revolution about the axis of the propulsion nozzle, so that said first wall has a first curved profile in an axial plane, said first curved profile being suitable for generating a flow of the propulsion gases adapted to operation at low altitudes;
• a second portion having a total length L, which is connected to said first portion at the connecting zone defining a curved contour discontinuity, said second portion comprising a second wall extending from the connecting zone to an outlet to exhaust the flow of the propulsion gases to an ambient environment, said second wall having a second surface of revolution about the axis of the nozzle, so that said second wall has a second curved profile in an axial plane, the connecting zone defining a change in slope between the first curved profile and the second curved profile, said second curved profile being suitable for generating a flow of the propulsion gases adapted to operation at high altitudes, wherein said connecting zone extends between said first portion and said second portion such that said curved contour discontinuity promotes detachment of the flow of the propulsion gases;
• and
• a device for controlled injection of at least one additional jet of gas into the main stream of the propulsion gases exhausted by the propulsion nozzle;
• said divergent section further comprising said controlled injection device having one or more orifices or a group of orifices produced axisymmetrically in said second wall of said divergent section, so that the injection of the additional jet of gas is carried out radially or inclined counterflow to the main stream, each of said orifices being arranged therein at a distance d from said connecting zone comprising the curved contour discontinuity, wherein d is equal to or less than 95% of the total length L of said second portion and greater than 1% of the total length L of said second portion so that the injection of the additional jet of gas:
• keeps the flow of the propulsion gases detached from the second curved contour by making use of the change in slope between the first curved profile and the second curved profile when moving from operation at low altitudes to operation at high altitudes;
• and
• causes detachment of the flow of the propulsion gases from the second curved contour by making use of the change in slope between the first curved profile and the second curved profile when moving from operation at high altitudes to operation at low altitudes.