Performance of Plug-Type Rocket Exhaust Nozzles

Abstract

The physical characteristics of a plug nozzle are described and compared with a conventional converging-diverging nozzle. The mathematical analysis of the aerodynamic performance of a plug nozzle is outlined, including the Prandtl-Meyer corner expansion of the flowing gas. The advantages of the plug nozzle in terms of superior performance at lower than design pressure ratio, smaller physical size and aerodynamic thrust vector control are described. A brief description is given of how these advantages can be utilized in liquid propellant rocket engines. Application of plug nozzles for solid propellant rocket engines is discussed primarily from the viewpoint of using the plug's movement to adjust for chamber pressure variation, to control thrust magnitude and direction and to control total impulse.