Ramjet Engine Fuel Injection Studies

The purpose of the investigation was to develop empirical methods for designing a fuel injection system applicable to sudden expansion burners using a coaxial inlet. An integral rocket/ramjet missile may utilize this type of fuel system. The primary objective of a liquid fuel injection system is to provide the combustion chamber with the proper amount of fuel in a pattern that will result in efficient combustion over the flight path of the missile. The relative amounts of fuel and air at the flameholding region are important in determining the efficiency of combustion. From the local fuel/air ratio relationship, a family of curves was plotted, which are functions of downstream distance and overall fuel/air ratio. With these curves, the injector was placed at the appropriate distance from the flameholding region to obtain stoichiometric conditions at that region. Subsequent tests using the AFAPL Ramjet Burner Thrust Stand Facility verified that efficient combustion was achieved.