C3 Propulsion and the Center for Green Manufacturing at the University of Alabama have demonstrated the feasibility of developing an Ionic Liquid (IL) gas generator.

Phases of the project included synthesis of several candidate ILs, design, fabrication, and testing of a gas generator prototype.

Advantages of Ionic Liquids vs Gel propellants

Gel propellant propulsion systems use pressure fed fuel systems in which a gas at high pressure is introduced into the fuel and oxidizer tanks and used to drive the propellants into the combustion chamber. The Future Missile Technology Integration (FMTI) program has demonstrated a gel motor with propellant tanks that are pressurized using a solid propellant-based gas generator. This gas generator consists of several stacked segments of solid propellant that are ignited sequentially, causing the pressure inside the gas generator chamber to oscillate between ignitions. This inherent pressure oscillation causes oscillations in the flow rate of the fuel and oxidizer gels, and makes it difficult to achieve precise control over the thrust produced.

The application of an ionic liquid-based gas generator has the potential to solve this problem in several respects:

• The flow rate of the ionic liquid can be precisely controlled to maintain a constant pressure in the fuel and oxidizer tanks to drive the propellants at a constant flow rate.
• The flow rate of the ionic liquid can be rapidly varied to vary to enable the pressure head in the fuel and oxidizer tanks to be controlled in order to control propellant flow rate.
• The properties of ionic liquids can be tailored based on the application. This will enable an ionic liquid that is well suited for use as a monopropellant to be developed.
• The Ionic liquid can be designed to be much less toxic than liquid monopropellants that are currently in use, such as hydrazine.

Possible gas generator applications

Gas generators have had and will continue to have a wide and variant use. Some examples of the many applications of gas generators are: rocket engine turbo-pump drive power, auxiliary or emergency power systems, vacuum aspiration, drive gas for reciprocating machinery, inflating air bags, pressurizing cavities, thermal heat, ejecting torpedoes, spin-starting turbo-pump rocket engines, turbine drive power for many different devices, rocket engine fuel source, rocket engine oxidizer source, hydraulic system pressurization, light sources (flares), and smoke generators.