Friday, April 1
The SEED program pairs NASA researchers with teams of college students to conduct research important to NASA. In previous years, the Carthage Microgravity Team has studied lunar dust filtration systems, angles of repose under lunar gravity, and propellant slosh in the Orion Crew Exploration Vehicle.
This year the team is working with NASA research engineer Rudy Werlink to design, build and test a zero-gravity fuel gauge. Led by Werlink and faculty mentor Kevin Crosby, they have designed a way to measure fuel volume using non-invasive PZT sensors and actuators. “We’re using sound waves to determine how much fluid is in a tank,” said team lead Kim Schultz, ’12, of Genoa City, Wis.
How it works
Their rig includes two tanks, a power amplifier, a data center, and a laptop computer, all housed in a large metal frame. They’ve attached four flat, flexible PZTs (piezoelectric transducers) to the wall of one tank. One of these PZTs is an actuator: “We send an electric current to the actuator and it vibrates,” said Cecilia Grove, ’11, of Walcott, Iowa. The other three PZTs are sensors. “They pick up that vibration and send the signal back to the data center.”
During the zero-gravity flights, the tanks will be filled with varying levels of water. Because the fluid level changes the stiffness of the tank wall, the level of vibration changes with different volumes, the students explain.
“It’s almost like you are creating an echo,” Cecilia explained. “How you hear an echo depends on the size and shape of the room you’re in.” She also said to think of a wine glass: “When you rub the top of a glass, the pitch changes based on the different levels of liquid. You can get very low tones with less liquid and high tones with high liquid, because the glass has a shorter or longer vibrational area.”
“From the vibration, we can analyze how much fluid volume is in the tank,” Kim said.
Important to NASA
The idea for the project was Werlink’s. The Carthage team added a way to measure the data in real time. “Our rig is able to fly and process data instantaneously,” Cecilia said. “That means that if you were on a shuttle, you could measure the fuel level whenever you needed the data. You could keep a constant log of it, like you have in a car.”
“Rocket fuel is challenging to make and it’s incredibly expensive,” she continued. “Any waste of fuel is a problem. You don’t want too much fuel, but you also have to make sure that you have enough. … It could save hundreds of millions of dollars if it’s precise.”
The students know the project works in 1G, the Earth’s gravity. “We’re hoping to see the same sort of responses in 0G, but we really can’t anticipate what’s going to happen, since fluid moves much differently when it’s in zero gravity,” Kim said.
“Our goal is to prove that this is a successful method.”