Evaluation of a Dual-Fluid Cold-Gas Thruster

A new dual-fluid concept was studied that could eventually find application for cold-gas propulsion for small space satellites or other constant flow applications. In basic form, the concept uses two different refrigerant working flui ds, each having a different saturation vapor pressure. The higher vap or pressure refrigerant remains in the saturation phase and is used to pressurize the lower saturation vapor pressure fluid (the prop ellant) which remains in the compressed liquid phase. A demonstration thruster concept based on this principle was designed and bu ilt to study its operating characteristics. An automotive-type elec tronic fuel injector was used to meter and deliver the propellant. Eject ed propellant mass and momentum were measured for several combinations of refrigerants and hydrocarbon fluids. The thruster h as the advantage of delivering relatively large total impulse at low ta nk pressure within a small volume.