by Kelsey D. Atherton, Popular Science
Thanks to a gas bubble and a liquid lubricant
The submarine of the future may come to America in a super fast bubble, traveling under water. Researchers at China’s Harbin Institute of Technology developed a new concept for submarine “supercavitation,” where an underwater vessel creates a pocket of air around itself. Inside this bubble, the submarine can travel much faster without friction of water creating drag and slowing it down. Theoretically, a supercavitated vessel using rocket engines could travel inside that air pocket at almost the speed of sound.
While the exact science of forming an air cavity within a liquid for submarines is complex, the phenomenon is easy to observe in a simple college prank. Clanking one full beer bottle on top of another compresses the beer in the bottom bottle, causing it to release air bubbles rapidly and overflow. For submarines, the bubbles come from a gas ejected out of a special nozzle at the nose, but the vessel has to be going a fast speed–thus compressing the air in front of it–in order for supercavitation to take effect. Once it’s going super fast inside a pocket of air, steering becomes hard as the vessel behaves almost like a missile.