SwRI investigates boiling processes in partial gravity

SwRI investigates boiling processes in partial gravity
by Clarence Oxford
Los Angeles CA (SPX) May 14, 2024

Southwest Research Institute (SwRI) is examining how liquids boil under partial gravity in a series of parabolic flights. This internally funded project, conducted with Texas A and M University, aims to understand boiling on different surfaces in partial gravity, which is crucial for future space missions to the Moon or Mars.

"We have so little data about how boiling works in reduced gravity," said SwRI's Kevin Supak, who leads the project. "Our experiment studies boiling in conditions that simulate lunar and Martian gravity levels using four different surfaces to examine how bubbles initiate and detach."

The experiment includes four heated surfaces with different treatments, submerged in a fluid that boils at 135 degrees Fahrenheit. These tests aim to show if engineered surfaces can improve boiling and bubble detachment in reduced gravity.

"When you're boiling water on the stove, you'll notice different bubble sizes and behavior between a stainless pot and a nonstick pot," Supak said. "This is because at the microscopic level, the surfaces look different and their roughness affects how bubbles initially form and stick to the surface. Rougher surfaces tend to form smaller bubbles and initiate boiling faster than smoother ones."

SwRI's Materials Engineering Department designed the surface treatments to evaluate how different material characteristics affect boiling.

"Bubble sizes, distribution and surface temperatures will be studied on three variations of stainless-steel surface treatments and one highly structured plastic surface," Supak explained. "It is difficult to simulate how boiling would work on the lunar and Martian surfaces in experiments conducted on Earth. However, parabolic flight tests offer researchers brief periods of partial gravity to gain more insight into these complicated processes."

In April, SwRI research engineers Dr. Eugene Hoffman, Dr. Akbar Whizin, and Emilio Gordon conducted the experiment on a parabolic flight campaign from Ft. Lauderdale. They gathered data during two flights at multiple gravity levels.

"If we're going to establish a sustained presence in space or on other worlds, boiling is a necessity," Supak said. "On Earth, we rely on gravity to help separate liquids and gasses through buoyancy. On the lunar or Martian surface, the lower buoyancy force will result in different boiling behavior. We need to know how hot to make surfaces to ensure efficient and safe heat transfer. This flight test will produce data that are directly applicable to improving our understanding of these processes."