Oxidizer Injection in Hybrid Propulsion

Hybrid rocket propulsion systems are attractive because they use a single fluid (LOX), and avoid the high injector part count of dual fluid propulsion systems. However, the hole drilling costs associated with fabricating the injectors can be large, and the small holes that are desirable to achieve optimum atomization can be either too expensive or impossible to produce. We propose a novel injector fabrication method that avoids expensive laser drilling and "platelet" processes, and will result in injectors with superior atomization performance. These injectors will atomize liquid oxidizer into an evenly distributed spray of very small (30 microns) droplets that will vaporize with decomposed solid fuel gases. The innovation lies in a new way to form very small, uniform, cylindrical holes in a thick (0.02 to 5 cm) metal injector plate. This fabrication process, developed by Alabama Cryogenic Engineering, Inc. (ACE), is based on a technique originally used in the fabrication of cryogenic heat exchangers.