HOW THE TESLA TURBINE WORKS

A boy watches a radio-controlled boat in the town of Smiljan, Croatia, Nikola Tesla's hometown.

Nearby is a bladeless waterwheel turbine of Tesla's design. The same principle powers his famous turbine engine.

I Introduction to How the Tesla Turbine Works

Most people know Nikola Tesla, the eccentric and brilliant man who arrived in New York City in 1884, as the father of alternating current, the form of electricity that supplies power to almost all homes and businesses. But Tesla was a prodigious inventor who applied his genius to a wide range of practical problems. All told, he held 272 patents in 25 countries, with 112 patents in the United States alone. You might think that, of all this work, Tesla would have held his inventions in electrical engineering - those that described a complete system of generators, transformers, transmission lines, motor and lighting - dearest to his heart. But in 1913, Tesla received a patent for what he described as his most important invention. That invention was a turbine, known today as the Tesla turbine, the boundary layer turbine or the flat-disk turbine.

Interestingly, using the word "turbine" to describe Tesla's invention seems a bit misleading. That's because most people think of a turbine as a shaft with blades - like fan blades - attached to it. In fact, Webster's dictionary defines a turbine as an engine turned by the force of gas or water on fan blades. But the Tesla turbine doesn't have any blades. It has a series of closely packed parallel disks attached to a shaft and arranged within a sealed chamber. When a fluid is allowed to enter the chamber and pass between the disks, the disks turn, which in turn rotates the shaft. This rotary motion can be used in a variety of ways, from powering pumps, blowers and compressors to running cars and airplanes. In fact, Tesla claimed that the turbine was the most efficient and the most simply designed rotary engine ever designed.

If this is true, why hasn't the Tesla turbine enjoyed more widespread use? Why hasn't it become as ubiquitous as Tesla's other masterpiece, AC power transmission? These are important questions, but they're secondary to more fundamental questions, such as how does the Tesla turbine work and what makes the technology so innovative?

The Tesla Turbine Engine

The job of any engine is to convert energy from a fuel source into mechanical energy. Whether the natural source is air, moving water, coal or petroleum, the input energy is a fluid. And by fluid we mean something very specific - it's any substance that flows under an applied stress. Both gases and liquids, therefore, are fluids, which can be exemplified by water. As far as an engineer is concerned, liquid water and gaseous water, or steam, function as a fluid.

At the beginning of the 20th century, two types of engines were common: bladed turbines, driven by either moving water or steam generated from heated water, and piston engines, driven by gases produced during the combustion of gasoline. The former is a type of rotary engine, the latter a type of reciprocating engine. Both types of engines were complicated machines that were difficult and time-consuming to build.

Consider a piston as an example. A piston is a cylindrical piece of metal that moves up and down, usually inside another cylinder. In addition to the pistons and cylinders themselves, other parts of the engine include valves, cams, bearings, gaskets and rings. Each one of these parts represents an opportunity for failure. And, collectively, they add to the weight and inefficiency of the engine as a whole.

Bladed turbines had fewer moving parts, but they presented their own problems. Most were huge pieces of machinery with very narrow tolerances. If not built properly, blades could break or crack. In fact, it was an observation made at a shipyard that inspired Tesla to conceive of something better: "I remembered the bushels of broken blades that were gathered out of the turbine casings of the first turbine-equipped steamship to cross the ocean, and realized the importance of this new engine".

Tesla's new engine was a bladeless turbine, which would still use a fluid as the vehicle of energy, but would be much more efficient in converting the fluid energy into motion. Contrary to popular belief, he didn't invent the bladeless turbine, but he took the basic concept, first patented in Europe in 1832, and made several improvements. He refined the idea over the span of almost a decade and actually received three patents related to the machine.

In the first patent, Tesla introduced his basic bladeless design configured as a pump or compressor. In the second patent, Tesla modified the basic design so it would work as a turbine. And finally, with the third patent, he made the changes necessary to operate the turbine as an internal combustion engine.

The fundamental design of the machine is the same, regardless of its configuration.

Date: 2015-02-16; view: 1099