Development of a Power-Efficient, Restart-Capable Arc Ignitor for Hybrid Rockets

This paper details the development of a new ignition system concept that circumvents many of the difficulties associated with the current state of the art for hybrid rocket ignition systems. The technology is based on the unique electrical breakdown properties of additively manufactured acrylonitrile butadiene styrene. Strategic application of an electric field across the top of an additively manufactured acrylonitrile butadiene styrene fuel grain induces an electrostatic arc along the horizontally stacked manufactured surface features, and results in a small amount of pyrolyzed fuel vapor. When this event occurs simultaneous with the introduction of an oxidizing flow, the ablated hydrocarbon vapor together with residual energy from the electrical arc rapidly seeds combustion. Multiple incremental prototype systems were designed, built, and tested. Best conditions for successful operation were discovered, including minimum ignition pressure, optimal geometry, and electrical power requirements. An embedded ignitor design demonstrated “hands-off” restart capability using a lab-scale 75-mm-diam hybrid motor. The system was restarted up to a dozen consecutive times with no propellant changeover or replenishment.