Tesla turbine

[5] In the pump, the radial or static pressure, due to centrifugal force, is added to the tangential or dynamic, thus increasing the effective head and assisting in the expulsion of the fluid.

In the motor, on the contrary, the first named pressure, being opposed to that of supply, reduces the effective head and the velocity of radial flow toward the center.

Again, in the propelled machine a great torque is always desirable, this calling for an increased number of disks and smaller distance of separation, while in the propelling machine, for numerous economic reasons, the rotary effort should be the smallest and the speed the greatest practicable.In standard steam turbines, the steam must press on the blades for the rotor to extract energy from the steam; the blades must be carefully oriented to minimize the angle of attack to the blade surface area.

In a normal operational mode, that peripheral pressure limits the flow of the incoming stream, and in this way, the Tesla turbine can be said to be self-governing.

Here we have to note that fluids start to behave like solid bodies at high relative velocities, and in the case of the Tesla turbine, we also have to take into consideration the additional pressure.

With this pressure and relative velocity toward the faces of the discs, the steam should start behaving like a solid body (SCS) dragging on the disks' surfaces.

[citation needed] 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.

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.

Continued improvements resulted in dramatically more efficient and powerful axial turbines, and a second stage of reduction gears was introduced in most cutting-edge U.S. naval ships of the 1930s.

The improvement in steam technology gave the U.S. Navy aircraft carriers a clear advantage in speed over both Allied and enemy aircraft carriers, and so the proven axial steam turbines became the preferred form of propulsion until the 1973 oil crisis, which drove the majority of new civilian vessels to turn to diesel engines.

It also suffers from other problems, such as shear losses and flow restrictions, but this is partially offset by the relatively massive reduction in weight and volume.

Under light load, the spiral taken by the fluid moving from the intake to the exhaust is tight, undergoing many rotations.

[citation needed] This will increase the shear losses and also reduce the efficiency because the gas is in contact with the discs for less distance.

Rice's test turbines, as published in early reports, produced an overall measured efficiency of 36–41% for a single stage.

With common fluids, the required disk spacing is dismally small causing [rotors using] laminar flow to tend to be large and heavy for a prescribed throughflow rate.

Volute rotor-matched Tesla-type machines of reasonable size with common fluids (steam, gas, and water) would also be expected to show efficiencies in the vicinity of 60–70% and possibly higher.

Applications of the Tesla turbine as a multiple-disk centrifugal blood pump have yielded promising results due to the low peak shear force.

[18] The device functions as a pump if a similar set of disks and a housing with an involute shape (versus circular for the turbine) are used.