Ryan Saffell

Date of Award


Document Type


Degree Name

Master of Science in Engineering (MSE)


Mechanical and Aerospace Engineering

Committee Chair

Marlow D. Moser

Committee Member

Robert A. Frederick Jr.

Committee Member

Kader Frendi


Rockets (Aeronautics)--Fuel, Fuel pumps--Rockets, Space vehicles--Propulsion systems, Rocket engines--Thrust


A program to examine and characterize two types of coaxial injectors and two types of screw swirl injectors in a small-scale rocket engine using gaseous oxygen and gaseous methane as main propellants has been developed. The mixing efficiency of this gas-gas scheme was evaluated by measuring the combustion efficiency at various characteristic chamber lengths, which allowed assessment of combustion stability of the system, and by changing parameters such as chamber pressure, mixture ratio, and injector post recess. Combustion efficiency for the shear coaxial element increased about 5% with chamber pressure and oxygen post recess. The shear coaxial injector combustion efficiency also increased about 15% from the shortest chamber length examined to the longest. Swirl coaxial and screw swirl performance increased about 7% with decreasing chamber length. The swirl coaxial element was more effective at mixing than the others and performance decrease was primarily due to heat loss. The screw swirl injector followed the same trends as the swirl coaxial injector.



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