Semi-hypergolic kerosene/hydrogen peroxide fuel system and its auto-ignition injector design

Combination of kerosene and hydrogen peroxide is a promising bipropellant due to its low cost, low toxicity, long storability, and high propulsive performance. This research formulates a kerosene based fuel which shows semi-hypergolic characteristics when in contact with hydrogen peroxide. Choosing a proper promoting medium, the formulated fuel (W2) dissolves ~8wt% of MAT in the solution with ~21wt% of kerosene, which makes the heating value of W2 closes to 32.5kJ/g. W2 and hydrogen peroxide present an ignition delay time of 21ms in droplet contact test. Since the delay time is still long comparing to conventional hypergolic propellant systems, a premixed type bipropellant injector design, namely, liquid-cyclonic injector unit has been preliminarily designed to obtain auto-ignition capability. In the injector unit, liquid fuel and oxidizer are tangentially injected into a small cylindrical chamber simultaneously to mix, and the formed hollow center space holds the vaporized propellants due to the heat release from the catalytic reaction in liquid phase. Ignition occurs when the gas-phase temperature reaches its auto ignition point. In hot-fire experiments, the designed injector shows a wide range in flow rate and O/F for stable auto-ignition. The shortest ignition delay of the injector unit is 38ms, however non-reproducible. Further study of the control factors for stable ignition delay is required.