Catalytic N2O Decomposition for Piloted Scramjet Ignition

N2O Project

 

Aircraft and missiles capable of rapid global strike and reconnaissance must fly at hypersonic speeds to achieve their performance goals. Future air-breathing hypersonic aircraft and missiles are expected to be powered by supersonic combustion ramjet (scramjet) engines. Unfortunately, scramjet engines only operate well at high speed and must be boosted there by a separate system. In the near term, this capability will probably be realized first in scramjet-powered missiles boosted to high speed with solid rocket motors. Ignition of the scramjet combustor at the end of the boost phase can be difficult to achieve due to the relatively low air pressures, temperatures, and residence times in the combustor as well as cold fuel and engine hardware. In a Phase I project Reaction Systems investigated an innovative new approach utilizing thermally stable catalysts or high temperature catalysts to decompose N2O, resulting in a very hot N2/O2 mixture that can be used to promote fuel ignition. Our approach incorporates the use of wall-mounted catalysts for increased heat flux. The use of a catalyst can significantly decrease ignition time delay and can also be combined with the liquid fuel injection system to achieve good fuel atomization, penetration, and mixing into the engine air flow.