Nikola Tesla invention from 100 years ago suddenly makes more sense today

Tesla in 1893.

Napoleon Sarony

Inventor Nikola Tesla has long been recognized for a body of work that ranges from brilliant (AC electricity) to baffling (an "earthquake machine"?). Scientists have studied one of his lesser-known inventions  in new detail, and they think they may have found new uses for it in the modern world.

Tesla's macrofluidic valve -- often just called the Tesla valve -- is a sort of odd-shaped conduit for fluids in which a main channel is interspersed with a series of diverting teardrop-shaped loops. The loops are oriented in such a way that fluids easily flow through in one direction, but when reversed, the flow is almost totally blocked.

In other words, it can be thought of as a sort of one-way or check valve, which anyone who has done a fair amount of plumbing or work with pumps will be familiar with. The advantage of Tesla's design is it has no moving parts that can wear out like the springs and other mechanisms on conventional check valves.

"While Tesla is known as a wizard of electric currents and electrical circuits, his lesser-known work to control flows or fluid currents was truly ahead of its time," explained Leif Ristroph, an associate professor at New York University's Courant Institute of Mathematical Sciences, in a statement.

Ristoph is senior author on a new paper in Nature Communications that looks more deeply into how the Tesla valve works and how it might be used in the 21st century.

By experimenting with replicas of the valve, which was patented in 1920, the researchers found that the flow-blocking capabilities of the valve "turn on" by creating turbulence and swirling vortices in the conduit at a certain rate of flow.

Comparison of flows in the reverse direction (right to left) at three different speeds. The water current is visualized with green and blue dyes, showing that the flows are increasingly disrupted at higher speeds.

NYU's Applied Mathematics Laboratory

"Moreover, the turbulence appears at far lower flow rates than have ever previously been observed for pipes of more standard shapes -- up to 20 times lower speed than conventional turbulence in a cylindrical pipe or tube," Ristoph adds. "This shows the power it has to control flows, which could be used in many applications."

Even more interesting, the valve actually works better with a flow that is not steady but instead comes in pulses or oscillations. This could make it ideal for use in high-vibration environments.

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"It could be used to harness the vibrations in engines and machinery to pump fuel, coolant, lubricant, or other gases and liquids," according to Ristoph.

Ironically, this may make the valve less likely to be applied in the famous electric vehicles of today that bear his name. That's because Tesla vehicles use battery packs and motors that vibrate less than internal combustion engines. But perhaps Elon Musk might one day find a use for the valves in SpaceX's powerful rocket engines, which produce plenty of vibrations.

Says Ristroph, "It's remarkable that this 100-year-old invention is still not completely understood and may be useful in modern technologies in ways not yet considered." 

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