Prandtl layer turbine

Details Prandtl layer turbine Prandtl layer turbine

1999-01-08

2001-05-01

Ryznic, John E. (Department: 3745)

Rotary kinetic fluid motors or pumps

Smooth runner surface for working fluid frictional contact

C415S914000

Reexamination Certificate

active

06224325

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to an apparatus used to transmit motive force between a fluid and a plurality of spaced apart rotatable members. The apparatus may be used to transmit the motive force from a fluid to the spaced apart members or, alternately, from the spaced apart members to the fluid.
BACKGROUND OF THE INVENTION
Prandtl layer turbines were first described by Nikola Tesla in U.S. Pat. No. 1,061,206 (Tesla). For this reason, these turbines are sometimes referred to as “Tesla Turbines”.
FIGS. 1 and 2
show the design for a prandtl layer turbine as disclosed in Tesla. As disclosed by Tesla, a prandtl layer turbine
10
comprises a plurality of discs
12
which are rotatably mounted in a housing
14
. Housing
14
comprises ends
16
and ring
18
which extends longitudinally between ends
16
. Discs
12
are spaced apart so as to transmit motive force between a fluid in housing
14
and rotating discs
12
.
The discs
12
, which are flat rigid members of a suitable diameter, are non-rotatably mounted on a shaft
20
by being keyed to shaft
20
and are spaced apart by means of washers
28
. The discs have openings
22
adjacent to shaft
20
and spokes
24
which may be substantially straight. Longitudinally extending ring
18
has a diameter which is slightly larger than that of discs
12
. Extending between opening
22
and the outer diameter of disc
12
is the motive force transfer region
26
.
The transfer of motive force between rotating discs
12
and a fluid is described in Tesla at column
2
, lines
30
-
49
. According to this disclosure, fluid, by reason of its properties of adherence and viscosity, upon entering through inlets
30
, and coming into contact with rotating discs
12
, is taken hold of by the rotating discs and subjected to two forces, one acting tangentially in the direction of rotation and the other acting radially outwardly. The combined effect of these tangential and centrifugal forces is to propel the fluid with continuously increasing velocity in a spiral path until it reaches a suitable peripheral outlet from which it is ejected.
Conversely, Tesla also disclosed introducing pressurized fluid via pipes
34
to inlets
32
. The introduction of the pressurized fluid would cause discs
12
to rotate with the fluid travelling in a spiral path, with continuously diminishing velocity, until it reached central opening
22
which is in communication with inlet
30
. Motive force is transmitted by the pressurized fluid to discs
12
to cause discs
12
to rotate and, accordingly, shaft
20
to rotate thus providing a source of motive force.
Accordingly, the design described in Tesla may be used as a pump or as a motor. Such devices take advantage of the properties of a fluid when in contact with the rotating surface of the discs. If the discs are driven by the fluid, then as the fluid passes through the housing between the spaced apart discs, the movement of the fluid causes the discs to rotate thereby generating power which may be transmitted external to the housing via a shaft to provide motive force for various applications. Accordingly, such devices function as a motor. Conversely, if the fluid in the housing is essentially static, the rotation of the discs will cause the fluid in the housing to commence rotating in the same direction as the discs and to thus draw the fluid through the housing, thereby causing the apparatus to function as a pump or a fan. In this disclosure, all such devices, whether used as a motor or as a pump or fan, are referred to as “prandtl layer turbines” or “Tesla turbines”.
Various designs for prandtl layer turbines have been developed. These include those disclosed in U.S. Pat. No. 4,402,647 (Effenberger), U.S. Pat. No. 4,218,177 (Robel), U.S. Pat. No. 4,655,679 (Giacomel), U.S. Pat. No. 5,470,197 (Cafarelli) and U.S. Reissue Pat. No. 28,742 (Rafferty et al). Most of these disclosed improvements in the design of a Tesla turbine. However, despite these improvements, Tesla turbines have not been commonly used in commercial environment.
SUMMARY OF THE INVENTION
In accordance with the instant invention, there is provided an apparatus comprising:
(a) a longitudinally extending housing having a fluid inlet port and a fluid outlet port;
(b) a plurality of spaced apart members rotatably mounted in the housing to transmit motive force between fluid introduced through the fluid inlet port and the members;
(c) each member having a pair of smooth opposed surfaces, each surface having an inner portion and an outer portion; and,
(d) at least one of the members having a width that is increased at at least one discrete location to alter the fluid flow over the surface of that member.
In one embodiment, at least one of the discrete locations is provided on the inner portion of at least one of the surfaces whereby the fluid passing over the surface forms a boundary layer and the thickness of the boundary layer is increased as it passes over the increased width at the discrete location provided on the inner portion.
In another embodiment, at least one of the discrete locations is provided on the outer portion of at least one of the surfaces whereby the fluid passing over the surface forms a boundary layer which delaminates as it passes over the surface and the delamination of the boundary layer is enhanced as it passes over the increased width at the discrete location provided on the outer portion.
At least one of the discrete locations is may be provided on the outer portion of at least one of the surfaces whereby the fluid passing over the surface forms a boundary layer which delaminates as it passes over the surface and the delamination of the boundary layer is enhanced as it passes over the increased width at the discrete location provided on the outer portion.
In another embodiment, at least one raised area is provided on at least one of the surfaces to provide the increased width. At least one of the raised areas may be provided on the inner portion. Alternately, or in addition, at least one of the raised areas may be provided on the outer portion.
Preferably, each of the members comprises a thin disc.
In accordance with the instant invention, there is provided a turbine comprising:
(a) a housing having a fluid inlet port and a fluid outlet port;
(b) a shaft rotatably mounted in the housing;
(c) a plurality of spaced apart discs mounted on the shaft and rotatable therewith, each disc having a radial inner end, a radial outer end and a pair of opposed surfaces extending therebetween, each surface having a radial inner portion and a radial outer portion; and,
(d) at least one of the discs having at at least one thickened portion at at least one discrete location to alter the fluid flow over the surface of that disc.
In one embodiment, at least one of the thickened portions is provided on the inner portion. Alternately, or in addition, at least one of the thickened portions may be provided on the outer portion.
In accordance with the instant invention, there is provided an apparatus comprising:
(a) a longitudinally extending housing having a means for permitting a fluid to enter the housing and means for permitting a fluid to exit from the housing;
(b) a plurality of spaced apart means for transmitting motive force between fluid introduced through the means for permitting a fluid to enter the housing and the spaced apart means, each spaced apart means having a pair of opposed surfaces whereby the fluid passing over the surface forms a boundary layer which delaminates as it passes over the surface; and,
(c) the apparatus having one or more of the characteristics selected from the group consisting of:
i. means for thickening the boundary layer as it passes over the surface; and,
ii. means for assisting in the delamination of the boundary layer as it passes over the surface.
In one embodiment, each surface has an inner portion and an outer portion and the means for thickening the boundary layer is provided on the inner portion of at least one of the surfaces. Alternately, or in addition, each surface has an inner p

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