Editing Tesla turbine (section)

==Design==
[[file:Tesla turbine system.png|thumb|View of Tesla turbine system]]
[[file:TeslaTurbineOriginal.png|thumb|View of Tesla turbine bladeless design]]

The guiding principle for developing the Tesla turbine is the idea that, to obtain the highest efficiency, the changes in the velocity and direction of movement of fluid should be as gradual as possible.<ref name="US patent|1061206"/> Therefore, the propelling fluid of the Tesla turbine moves in natural paths, or streamlines, of least resistance.

A Tesla turbine consists of a set of smooth disks, with [[nozzle]]s applying a moving fluid to the edge of the disk. The fluid drags on the disk through [[viscosity]] and the [[adhesion]] of the surface layer of the fluid. As the fluid slows and adds energy to the disks, it spirals into the center exhaust. Since the [[Rotor (turbine)|rotor]] is a simple disk, it is more robust and easier to manufacture, compared to a traditional bladed turbine.

Tesla wrote:<ref name="rexresearch"/> 
<blockquote>
This turbine is an efficient self-starting prime mover which may be operated as a steam or mixed fluid turbine at will, without changes in construction and is on this account very convenient. Minor departures from the turbine, as may be dictated by the circumstances in each case, will suggest themselves but if it is carried out on these general lines it will be found highly profitable to the owners of the steam plant while permitting the use of their old installation. However, the best economic results in the development of power from steam by the Tesla turbine will be obtained in plants especially adapted for the purpose.
</blockquote>

Smooth rotor disks were originally proposed, but these gave poor starting torque. Tesla subsequently discovered that smooth rotor disks with small washers bridging the disks in about 12 to 24 places around the perimeter of a 10″ disk and a second ring of 6–12 washers at a sub-diameter made for a significant improvement in starting torque without compromising efficiency.