Modal Propellant Gauging in Low Gravity.

Area of Science:

• Aerospace Engineering
• Mechanical Engineering
• Physics

Background:

• Accurate propellant gauging is critical for spacecraft missions and orbital fuel depots.
• Conventional gauging methods struggle with accuracy at low propellant levels and in microgravity environments.
• Sloshing liquids further complicate propellant level measurements.

Purpose of the Study:

• To present results from parabolic flight testing of a novel low-gravity propellant gauging technology.
• To evaluate the performance of the modal propellant gauging (MPG) method.
• To demonstrate the MPG method's robustness and accuracy across various conditions.

Main Methods:

• Utilized parabolic flight testing to simulate low-gravity conditions.
• Employed modal propellant gauging (MPG) by detecting resonant acoustic mode shifts.
• Developed and applied an algorithm for real-time identification of modal response behaviors in zero-gravity.

Main Results:

• MPG demonstrated robustness against sloshing liquids in zero-gravity with errors under 1.5%.
• MPG showed comparable resolution to existing methods for settled propellant.
• Lab measurements indicated less than 1.0% error for fill-fractions between 10-50% in 1-g.
• MPG proved particularly effective at low fill-fractions where conventional methods fail.

Conclusions:

• The modal propellant gauging (MPG) method offers a reliable solution for low-gravity propellant level measurement.
• MPG technology is suitable for small satellite missions and propellant transfer operations in orbital fuel depots.
• The developed algorithm enables automated fill level assignment by correlating zero-g and 1-g frequency response functions.