Additive Manufacturing of Solid Rocket Propellant Grains

摘要

COMPOSITE solid rocket propellants are the workhorses invarious strategic vehicles and space launch vehicles. Traditionally,composite propellant slurries are cast into cylindrical grains withone or more longitudinal ports to enable radial burning. A mandrel inthe desired shape is placed in the mold during the casting process, and itis subsequently removed from the cured propellant grain, leavingvacant port(s). The geometry of the port dictates the evolution of theburning surface over time, and thus the thrust time profile of the rocketmotor. Various port geometries have been used in the past to achieveintended internal ballistics [ I ]. However, the mandrel-based process ofintroducing ports in composite propellant grains limits the complexityof port shapes that can be realized, and it prohibits the introduction offully submerged ports. Gas-permeable or porous propellant grains areknown to exhibit much higher burning rates than nonporous grains,due to additional convective heat transfer [21. Yet, a major reason fornot being able to realize the benefits of porous propellants in practicalsystems is the tediousness and variability involved in their manufactureand the associated uncertainties.