Seeded Hydrogen in Nuclear Thermal Propulsion Engines

Abstract

Using a NASA Design Reference Architecture, a nuclear thermal propulsion engine model was developed to numerically examine the effects on engine performance by adding heavy noble gases into the hydrogen propellant stream (seeding) before the reactor inlet. Seeded hydrogen, up to a maximum seed mass concentration of 55.85%, increased engine performance by reducing pressure losses, decreasing reactor power, and improving convective heat transfer. Seeding hydrogen also has the potential to increase the engine thrust by up to 13.75% by using the decreased pressure losses. The decreased reactor power reduces the cool down propellant mass of the vehicle, whereas the increased bulk density of the propellant can provide more overall. The tradeoff for introducing a seed into the hydrogen stream is lowered specific impulse.