Date of Award

2019

Document Type

Thesis

Degree Name

Master of Science in Engineering (MSE)

Department

Mechanical and Aerospace Engineering

Committee Chair

Robert A. Frederick, Jr.

Committee Member

L. Dale Thomas

Committee Member

Jason T. Cassibry

Subject(s)

Nuclear propulsion., Space vehicles--Nuclear power plants., Hydrogen.

Abstract

Using the NASA Design Reference Architecture, Nuclear Thermal Propulsion engine and Mars transfer vehicle models were developed to numerically examine the effects of adding heavy noble gases into the hydrogen propellant stream (seeding) on round trip transit times (baseline of 357 days). Seeded hydrogen, up to maximum seed mass concentration (MSMC) 55.85%, increased engine and vehicle performance by reducing pressure losses, decreasing reactor power, and increasing the overall change in velocity while assuming constant vehicle volume and dry mass. The tradeoff was lowered specific impulse and increased net propellant mass, resulting in increased vehicle wetted mass. Vehicle performance increased at MSMC and provided a best case 32-day reduction in transit time vs. pure hydrogen. Vehicle performance was comparable to densified pure hydrogen at 30% seed mass concentration. When taken in combination with densified hydrogen, vehicle performance increased further by providing a 41-day reduction in transit time at MSMC.

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