Development of the injector head for 400 n bipropellant thruster for apogee kick engine

Abstract

In this research project the development of the injector head for a 400 N bipropellant thruster for use in apogee kick engine module is described. The proposal is based on the concept of a compact head where the injector elements and the feed manifold are machined on the face of three plates, one for the distribution of the feed propellants, one for the oxidizer and one for the fuel. The vortex chambers of the swirl injector elements are located on a common axis. The atomization jets at the exit of the injector throat form a thin liquid film of approximate cone shaped surface. The apexes of the cone shaped surface are slightly displaced in the axial direction and the semi-angle of the cones are such that the inner cone intercepts the outer cone some distance into the combustion chamber. The interception of the two thin film promotes a fast ant thorough mixing of the propellants. The three plates are bonded together by a process of solid state diffusion. The challenge for the designer of the injector head is to obtain a geometry of the injector elements and a disposition on the face of the plate than controls the distribution of the mass flux and the oxidizer to fuel mixture ratio for a fast and thorough burn of propellants. The spatial distribution of the mass flux and the mixture ratio are also responsible for promoting a flow profile of the combustion products inside combustion chamber that minimizes the convective heat load onto the surface of the combustion chamber. This research project builds on previous projects carried on at INPE with support of FAPESP and participation of Equatorial Systems and Diprofil. In the previous phases of the project working prototypes of the injector head were produced and tested, validating the swirl injector concept and the use of the solid state diffusion bonding. (AU)