Spray Ignition Studies on a Green Hypergolic Hybrid Rocket Propellant

The paper describes design and validation of a test platform for ignition experiments on hypergolic propellants in a spray-test configuration. This forms part of an ongoing effort to characterize ignition of a promising non-toxic hypergolic hybrid rocket propellant. The propellant to be characterized consists of rocket grade hydrogen peroxide (RGHP) as the oxidizer, high-density polyethyelene (HDPE) as fuel and NaBH4 as the energetic additive embedded in the HDPE fuel matrix. The aim of the project is to ignite the HDPE + NaBH4 samples in a spray of RGHP to emulate a real rocket motor oxidizer feed system. To that end, a combustion chamber was designed around which RGHP flow and pumping system was constructed. The system was automated to allow for remote operation. Finally, a 25% NaBH4 weight-loaded sample was ignited under a spray of RGHP to validate the system. The ignition event was recorded using a high-speed camera. Ignition delay was determined and the growth of the ignition kernel was studied. With the spray-test platform validated, the setup is ready for further tests, with future direction of the work guided by the preliminary results obtained so far.