Prandtl layer turbine

Details Prandtl layer turbine Prandtl layer turbine

1999-01-08

2001-07-17

Ryznic, John E. (Department: 3745)

Rotary kinetic fluid motors or pumps

Smooth runner surface for working fluid frictional contact

Reexamination Certificate

active

06261052

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 dscribed 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. ent 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; and,
(b) at leat one plurality of spaced apart members, each member rotatably mounted in the housing and having a pair of opposed surfaces to transmit motive force between fluid introduced through the fluid inlet port and the spaced apart members, the surface area of the opposed surfaces varying between at least some of the immediately adjacent spaced apart members.
In one embodiment, the spaced apart members have an inner edge and an outer edge and, for at least a portion of the spaced apart members, the distance between the inner edge and the outer edge of a spaced apart member varies to that of a neighbouring spaced apart member. The spaced apart members may have a first end and a second end and the distance between the inner edge and the outer edge of the spaced apart members increases from the first end towards the second end. Alternately, the spaced apart members may have a first end and a second end and the distance between the inner edge and the outer edge of the spaced apart members increases from the first end to the second end. The air inlet port may be positioned either upstream or downstream of the first end.
In another embodiment, the at least one plurality of spaced apart members comprises a first and a second plurality of spaced apart members, the first and second plurality of spaced apart members each having a first end and a second end, each spaced apart member having an inner edge and an outer edge and, for at least a portion of the spaced apart members of each plurality of spaced apart members, the distance between the inner edge and the outer edge of a spaced apart member varies to that of a neighbouring spaced apart member. The variation in the spacing and the position of the inlet port may vary as similarly vary as discussed above.
In another embodiment, the spaced apart members comprise discs each of which has an outer diameter and, for at least a portion of the discs, the outer diameter of one spaced apart disc varies to the outer diameter of the immediately adjacent spaced apart disc. The outer diameter of the spaced apart discs may increase or decrease in the downstream direction. Alternately, or in addition, the spaced apart members may comprise discs each of which has an inner diameter defining an inner opening and, for at least a portion of the discs, the inner diameter of one spaced apart disc may vary to the inner diameter of the immediately adjacent spaced apart disc.
In another embodiment, the at least one plurality of spaced apart members comprises a first and a second plurality of spaced apart discs, the first and second plurality of spaced apart discs each having a first end and a second end, each spaced apart member having an inner diameter defining an inner opening and an outer diameter and, for at least a portion of the spaced apart members of each plurality of spaced apart discs, the inner diameter of a spaced apart disc varies to that of a neighbouring spaced apart disc.
In accordance with the instant invention, there is also provided an apparatus comprising:
(a) a first means for transmitting motive force between a fluid and a first plurality of rotatable spaced apart members and having an upstream end and a downstream end;
(b) a second separate means for transmitting motive force between a fluid and a second plurality of rotatable spaced apart members and having an upstream end and a downstream end; and,
(c) means for introducing the fluid to the upstream ends.
In one embodiment, the upstream ends are positioned opposed to each other. The first and second means may be rotatably mounted on a common shaft.
In another embodiment, the spaced apart members have an inner edge and an outer edge and, for at least a portion of the spaced apart members of each of the first and second means, the distance between the inner edge and the outer

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