High-Performance Reticulated SiC Foam Injector for Liquid Rocket Engines

Hydrocarbon-based fuels are being considered for reusable rocket engines because of high propellant density and high thrust-to-weight. Current developments are focusing on staged combustion cycles utilizing oxygen-rich preburners with liquid-liquidinjection. A need exists for advanced injectors with high mixing efficiencies, improved combustion stability and reusability. Recent developments in porous reticulated ceramic foams offer promise to increase injector performance via improved mixingefficiencies and combustion stability; increase robustness and reliability via reduced vulnerability to particulate fouling and coking contamination of injector orifices; and decrease cost via eliminating the need for precision laser machining numeroussmall diameter orifice holes, thus greatly simplifying fabrication.The objective of this Phase I program is to demonstrate the feasibility of producing a reticulated SiC foam bipropellant injector assembly with improved performance and simplified fabrication over traditional designs that may suitable for booster-scale,hydrocarbon-based rocket engine application. Reticulated SiC foam specimens of various porosities and densities will be produced and experimentally evaluated to determine their respective liquid and gaseous pressure drop characteristics, dischargecoefficients and potential for use in an advanced propellant injector design. A prototype single-element SiC foam bipropellant injector assembly will be designed, fabricated and delivered to OSD for hot-fire ground test evaluation. Reticulated ceramic and refractory metal foams are an enabling class of materials which are suitable for a variety of extreme environment applications including chemical rocket propulsion injectors, hot gas and molten metal filters, catalyst supports andradiant burners. Ceramic foams are currently being used as a low-density core in high-rigidity ceramic composite sandwich structures and ultra-lightweight laser mirrors and optics.