Low-Power Water-Vapor Generation using Ultrasonic Atomizer for Use with Microwave Electrothermal Thrusters
Open Access
- Author:
- Detwiler, Jonathan
- Area of Honors:
- Aerospace Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Sven G Bilen, Thesis Supervisor
Robert G. Melton, Thesis Honors Advisor - Keywords:
- MET
Electric Propulsion
Atomizer
Ultrasonic
Microwave
Water Vapor
Aerospace
Propulsion - Abstract:
- Water vapor, as a non-toxic, liquid-storable, and environmentally friendly substance, is a compelling propellant to use with Microwave Electrothermal Thrusters (METs). Due to the power limitations of spacecraft that would utilize METs, such as CubeSats, the vaporization of liquid water must be achieved with as little power as possible. Utilizing an ultrasonic atomizer was investigated as it provides a flow of water with increased surface area by generating small water particles via ultrasonic mechanical vibrations. In order to efficiently heat these particles, the stream was injected into a heated pipe containing copper foam, used to increase the heated surface area with which the flow interacts. Testing of this system found that utilizing copper foam decreased the specific energy of the system by 20%. When compared to existing water vaporizers designed for similar thermoelectric propulsive devices, a 33–79 % decrease in specific energy would be required for this system to be comparable. As no optimization of this system was attempted after proof-of-concept testing, further work to decrease this specific energy could bring the specific energy closer to these existing systems. It was also found that ultrasonic atomizers do not provide as simple of mass flow control as conventional vaporizers do; however, varying propellant pressurization could provide this control capability. Further work will involve pressurization of propellant tanks and changes to the testing apparatus to allow for mass flow control and optimization of the system, with the goal of decreasing specific energy.