Propellant Atomization for Porous Injectors

Abstract

Porous injectors represent an alternative injection concept to coaxial injectors for rocket engine applications using gas/liquid propellant combinations such as liquid oxygen (LOX)/hydrogen (H 2 ). This paper summarizes the main design features of porous injectors and proposes a mechanism of atomization for porous injectors that is considerably different to the atomization mechanism for coaxial injectors. The results of hot-fire test campaigns are presented, in which several parameters relevant to the injection process were varied: the injection velocities and momentum fluxes, the combustion chamber Mach number at the beginning of the nozzle contraction, and the LOX injector diameter. All hot-fire tests were conducted at P8 test facility for high pressure combustion research at the DLR site of Lampoldshausen with 50-mm-diameter combustion chambers operated with LOX∕H 2 at sub-and supercritical chamber pressures between 30 and 100 bar. The results presented here are supporting the proposed mechanism of atomization and allow derivation of some general design guidelines for porous injectors.