Spray Ignition of a Promising Hypergolic Hybrid Rocket Propellant

The current study involves a promising green hypergolic hybrid rocket propellant consisting of rocket grade hydrogen peroxide or RGHP as oxidizer, high density polyethylene or HDPE as fuel and NaBH4 as the energetic additive embedded in the HDPE fuel matrix. Previous work, including by the authors, dealt with parametric characterization of this propellant’s ignition properties by means of standard drop-on-solid tests. Hence, the natural next step was to study ignition under oxidizer sprays which emulate real rocket motor oxidizer feed systems. Additionally, while data on ignition delay exists for this propellant, very little is known about transition from ignition to fuel burn, its ignitability and scant information exists in the literature about the chemical species involved. The present work seeks to use high speed visible and infrared imaging to study the initial ignition kernel and its transition to full sample burn under sprays of oxidizer perpendicularly impacting the fuel surface. Additionally, the use of optical filters will aid in the determination of important chemical species taking part in the hypergolic reaction/ignition process. Finally, different parameters will be varied to study ignitability of this propellant combination. The study is expected to lead to a deeper understanding of hypergolic ignition and aid in the adoption of this promising propellant in real rocket motors.