The research examines the idea of using hypergolic ignition in a hybrid motor. The main advantages of the hybrid motor are the facts that it is simple, controllable and exhibits shut-off and re-ignition capability. The ignition delay between the fuel and the oxidizer has to be minimal and provide the adequate heat release to assure combustion.
Hydrogen peroxide is considered as an excellent oxidizer in hybrid systems. Wernimont and Heister investigated the performance of a hybrid rocket motor that used hydrogen peroxide and polyethylene. Ignition was achieved by using a catalytic bed, which decomposed hydrogen peroxide and allowed the fuel to burn with the oxidizer. However, the introduction of a catalytic bed increases weight and affects the performance of the motor.
The ignition of the solid hydrocarbon fuel (HTPB or PE) in a hybrid system can be accomplished by utilizing a hypergolic combination of oxidizer and fuel. For an efficient hybrid system, the ignition of the fuel grain has to be fast and effective, i.e., to obtain low ignition delay and high heat release. High performance materials and direct hypergolic ignition between the solid fuel and the oxidizer seems to be a suitable solution for the mentioned above. Research has been conducted on the ignition delay obtained from the hypergolic ignition of gelled kerosene with suspended catalyst/reactive particles as done by Natan et al, showing that the addition of catalyst in a gelled inert fuel can allow efficient hypergolic ignition.
That same idea can be implemented in a hybrid motor in which the catalyst is embedded in the solid fuel to allow ignition upon contact with the hydrogen peroxide. Within the frame of the present work the ignition delay and feasibility of a hypergolic ignition between a liquid oxidizer and a solid hydrocarbon fuel was investigated. Various catalysts and fuel types at different conditions have been studied. The effects of the concentration of the catalyst in the fuel, the fuel temperature and the ambient pressure on the ignition delay were investigated.
This was done by conducting drop-on-solid tests in a combustion bomb in which the ignition delay was measured using a high-speed camera.
The results indicate that this solution can be implemented to obtain a hybrid hypergolic igniter.
