Hypergolic Ignition Characterization of Less-Toxic Bipropellants Using Hydrocarbon Fuel Blend and Hydrogen Peroxide

Derivatives of Hydrazine as fuel and Mixed Oxides of Nitrogen (MON-3) as oxidizer are extensively used in bipropellant thrusters of spacecrafts. This hypergolic propellant combination is primarily used for its multiple restart capabilities and good storability characteristics. However, Hydrazine is highly toxic and MON-3 is highly corrosive in nature. Rocket grade Kerosene as fuel and concentrated Hydrogen peroxide as oxidizer can serve as a potential replacement. This combination comes under the class of propellants termed as "Green Propellants" which have low toxicity, lesser environmental impact and low cost of operation. The reason for this propellant combination not being used in spacecrafts yet is due to its non-hypergolic nature. Fuel blend with suitable reactive additive that can decompose Hydrogen peroxide upon contact is one of the techniques of inducing hypergolicity into the system. In this work, Ignition Delay Time (IDT) of the propellant combination is evaluated through drop contact test using a high speed camera with 1 ms resolution. Drop contact tests were carried out by varying the O/F ratio and it is found that shorter IDT is achieved under fuel rich condition. IDT as low as 5 ms is achieved for the optimized Kerosene fuel blend with 90% Hydrogen peroxide compared to 3 ms for MMH (Mono Methyl Hydrazine) and MON-3 evaluated using the same experimental setup. The performance of optimum fuel blend is subsequently evaluated through thruster trial.