US3690784A

US3690784A - Turbine

Info

Publication number: US3690784A
Application number: US80556A
Authority: US
Inventors: Desmond J Farrow
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-10-14
Filing date: 1970-10-14
Publication date: 1972-09-12
Anticipated expiration: 1989-09-12

Abstract

A small-sized turbine designed for use with a steam generating chamber comprises a pair of rotors mounted in spaced relation on an axial support for rotation about the axis in clockwise and counter-clockwise directions, respectively, according to the application of steam to one or the other of the rotors for obtaining either forward or reverse operation, as desired. Each rotor is formed of a central section having a plurality of circumferentially spaced pockets in the periphery thereof, with the peripheral edges between these pockets being slightly sloped for receiving the steam input and causing the same not to merely strike the opposite side of the pocket, but to curve radially inwardly and initiate the formation of a vortex flow, and a pair of rotor sections disposed on opposite sides of the central rotor section being keyed thereto for rotary movement therewith and having lateral apertures spaced about the periphery thereof which extend from the side adjacent the central rotor to the opposite outside face, for providing a reaction outlet from each of the pockets of the central rotor section. The rotors are disposed in separate stators, each having spaced steam inlets for introducing the steam tangentially over the sloped peripheral edges of the central rotor section, and are keyed to a shaft which is supported in bearings positioned between and outside the stator housings for causing rotation of the same in a predetermined direction.

Description

United States Patent Farrow 1 TURBINE [72] Inventor: Desmond J. Farrow, RD. 2, North East, Md. 21901 221 Filed: on. 14, 1970 211 Appl. 1%.: 80,556

Primary Examiner-C. J. Husar Attorney-Oblon, Fisher & Spivak [57] ABSTRACT A small-sized turbine designed for use with a steam 51 Sept. 12, 1972 generating chamber comprises a pair of rotors mounted in spaced relation on an axial support for rotation about the axis in clockwise and counterclockwise directions, respectively, according to the application of steam to one or the other of the rotors for obtaining either forward or reverse operation, as desired. Each rotor is formed of a central section having a plurality of circumferentially spaced pockets in the periphery thereof, with the peripheral edges between these pockets being slightly sloped for receiving the steam input and causing the same not to merely strike the opposite side of the pocket, but to curve radially inwardly and initiate the formation of a vortex flow, and a pair of rotor sections disposed on opposite sides of the central rotor section being keyed thereto for rotary movement therewith and having lateral apertures spaced about the periphery thereof which extend from the side adjacent the central rotor to the opposite outside face, for providing a reaction outlet from each of the pockets of the central rotor section. The rotors are disposed in separate stators, each having spaced steam inlets for introducing the steam tangentially over the sloped peripheral edges of the central rotor section, and are keyed to a shaft which is supported in bearings positioned between and outside the stator housings for causing rotation of the same in a predetermined direction.

12 Claims, 4 Drawing Figures STEAM GENE RATOR,

PATENTEDsEP l2 m2 3.890.784

sum 1 or 2 TO INLET 33 GENERATOR FIG. 3

INVENT OR DESMOND J FARROW By 060" Ffr/w; S un/c ATTORNEYS PKTENTED 3.690.784

INVENTOR DESMOND J. FARROW BY 06m, PM 41 MM ATFURNFYS TURBINE BACKGROUND OF THE INVENTION The present invention relates generaily to gas or steam-powered turbines and more particularly to a turbine which is powered by a small boiler or steam generator and yet is small enough and of suitable efficiency to permit the same to be used for driving motor vehicles, farm equipment at remote locations, and the like.

In recent times, much consideration has been focused on the quality of our environment and particularly upon the dangerous pollution of our atmosphere by the internal combustion engines powering our automotive vehicles, which continue to rapidly increase in number and crowd the nations highways and, in turn, fill the air with pollutants resulting from the operation thereof. New standards of pollution control are being urged upon the manufacturers of automotive vehicles and, in fact, some laws have been proposed which effectively would eliminate the internal combustion engine in its conventional and well-known form as a means of powering these vehicles. The search for a suitable substitute for the internal combustion engine which does not suffer from the same shortcoming of producing such sizable quantities of pollutants has caused many engineers and designers of automotive vehicles to reconsider the steam automobile which was so popular several decades ago.

In the external combustion engine, the fuel is burned outside the engine to produce a vapor to run it. Thus, unlike that in a gasoline engine, combustion is practically complete and little or no deadly carbon monoxide or unburned hydrocarbons are discharged into the air. Instead, the principle gaseous product is just harmless carbon dioxide.

Large gas or steam-powered turbines have in recent years proved themselves to be capable of competing with conventional engines when used for the propulsion of ships, locomotives and aircraft. However, attempts to produce turbines which are small enough to make the same suitable for driving automotive vehicles and the like, yet which are of such efficiency to provide adequate power therefor, have not proven to be nearly as successful. One of the principle reasons that small turbines have not been able to compete with conventional engines is that, in order to achieve a high degree of efficiency with turbines, the peripheral velocity of the rotor must increase in proportion with the flow velocity of the gas or steam, which evidently must be as high as possible if a sufiicient amount of energy is to be carried thereby, and in the case of small turbines having a diameter of, for example, 15-30 centimeters, this would generally require operation at an extremely high speed, such as, for example, 50,000 r.p.m., which also is extremely disadvantageous for various reasons.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an improved small-sized turbine for use with a small boiler or steam generator for powering an automotive vehicle or the like.

Another object of the present invention is to provide a gas or steam-powered turbine which is small, but highly efficient over a great range of speeds.

Still another object of the present invention is to provide a turbine which is operable at relatively low peripheral speeds without loss of efficiency.

Yet another object of the invention is to provide a small and highly efficient gas or steam-drive turbine which is operative for driving a shaft in either direction, as desired, for effecting forward and reverse operations of a vehicle associated therewith.

A still further object of the invention is to provide a small-sized and highly efficient gas or steam-driven turbine which is simple in construction and relatively inexpensive to operate and maintain.

These and other objects are attained by a turbine comprising a pair of rotors mounted in spaced relation on a shaft for rotation about the axis thereof in clockwise and counter-clockwise directions, respectively, according to whether steam or gas is applied to one or the other of the rotors for providing either forward or reverse operation, as desired. Each rotor is formed of a central disc-like section having a plurality of circumferentially spaced pockets in the periphery thereof, with the peripheral edges between these pockets being slightly sloped for receiving the steam input and causing the same not to merely strike the opposite side of the pocket, but to curve radially inwardly and initiate the formation of a vortex flow, and a pair of disc-like rotor sections disposed on opposite sides of the central rotor section being keyed thereto for rotary movement therewith and having lateral apertures spaced about the periphery thereof which extend from the sides adjacent the central rotor to the opposite outside faces, for providing a reaction outlet from each of the pockets of the central rotor section. The rotors are disposed in separate stators, each having steam inlets for introducing the steam tangentially over the sloped peripheral edges of the central rotor sections, and are keyed to the shaft which is supported in bearings positioned between and outside the stator housings for causing rotation of the same in a predetermined direction. By keeping the shaft-supporting bearin gs outside of the turbines, operation of the turbine is not hindered thereby and the bearings are not subject to corrosion by the steam and do not have to be sealed as they otherwise would. This arrangement is less expensive, permits easy lubrication of the bearings, and takes up less room inside the turbines.

To permit operation either forwardly or in reverse, these spaced rotors are oppositely disposed on the shaft so that the peripheral edges of the central section of one are sloped in a clockwise direction while the peripheral edges of the central section of the other are sloped in a counter-clockwise direction, when the same are viewed from one axial end thereof. Obviously, the outside rotor sections of each rotor are also oppositely transposed for appropriately lining up the corresponding lateral apertures therein with the circumferentially spaced pockets of the respective central rotor section. A three-way valve is provided for controlling the application of steam to one or the other of the stator housings for effecting operation of the turbine in either one or the other direction. Because of the combination impulse and reactive jet effect of the turbine of this invention, it has been found to be very highly efficient over a great range of speeds.

3 BRIEF DESCRIPTION OF THE DRAWINGS Various other objects, features and attendant advantages of the present invention will be more readily appreciated as the same become better understood by reference to the following detailed description when considered in connection with the accompanying drawings in which like reference numerals designate like or corresponding parts throughout the several views, and wherein:

FIG. 1 is a longitudinal sectional view of a preferred embodiment of the present invention;

FIG. 2 is a sectional view of the embodiment illustrated in FIG. 1, taken along the line 2-2 thereof;

FIG. 3 is an end view of a central rotor section of the device illustrated in FIG. 1 showing the novel sloped peripheral edges thereof for obtaining a vortex flow pattern within the circumferentially spaced pockets therein; and

FIG. 4 is an end view of one of the outside rotor sections showing the lateral apertures therein which are aligned with the pockets of the central rotor section for producing a reactionary jet flow therefrom.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to FIG. 1, there is shown a turbine apparatus constructed in accordance with the teachings of the present invention which comprises a pair of rotors generally indicated by the reference numerals l and a being rotatably mounted in spaced relation on a shaft 11. The shaft 11 is supported in bearings 12 which are suitably mounted in races 13 of conventional form positioned within a housing 14 suitably secured to a main support, not shown. A pair of turbine cylinders, or chamber-defining means, 15 and 150 are positioned on the shaft 11, one each being disposed on opposite sides of the housing 14 in abutting relation therewith and being separated thereby, the cylinders being maintained in their respective positions by snap rings 16 engaging the shaft 11 on the sides of the cylinders opposite the sides thereof contacting the housing 14.

Centrally disposed within each of the cylinders 15 and 150 are the rotors l0 and 10a, respectively, each of which is secured therein against axial displacement on the shaft 1 l by another set of snap rings 18. Each of the rotors is constructed from a plurality of component parts comprising a central rotor section 19 having a plurality of circumferentially spaced pockets, or cavities, 20 in the substantially cylindrical outer face or periphery thereof, and a pair of outer rotor sections 21 having substantially the same diameter as the central rotor section 19 which are positioned, respectively, against the opposite faces thereof. An upstanding lug, or key, 23, which may be integrally formed on the shaft 11, engages aligned

slots

24 and 25, respectively cut in the central rotor section 19 and each of the outer sections 21 from the shaft-receiving axial bores therein, for preventing relative angular displacement of the rotor sections and for causing the shaft 11 to be concurrently driven with the rotors.

A plurality of apertures 27, corresponding in number to the pockets 20 in the central rotor section 19, are provided in each of the outer rotor sections 21 for permitting flow from the pockets 20 of each central rotor in substantially either axial direction therefrom into the surrounding cylindrical chamber formed by the respective cylinder ends 15 and a tubular stator member 29 fixedly secured therebetween. An annular chamber, divided into three axially spaced units, is provided about the outside periphery of the stator 29 by a tubular ring 30 having four spaced flanges, or transverse annular ring sections 31, integrally formed thereon, or being fixedly secured thereto, and projecting radially inward therefrom to engage and be secured to the stator, as by welding or the like. Flow into the central unit of this annular chamber and from there into the pockets 20 in the central rotor section 19 from a source 32, such as, for example, a small boiler or steam generator, is achieved through a radial input port 33 formed in the tubular ring 30 and through a plurality of apertures 34 angularly oriented in the stator 29, and flow from the cylindrical chamber surrounding the rotor is through similar apertures in the stator which exit into the outside units of the annular chamber surrounding the same for discharge through an exhaust port 35 in the ring member 30.

In assembling the turbine apparatus on the shaft 11, one of the cylinder ends 15 having a central opening therein is positioned on the shaft against one end of the shaft-supporting housing 14. The inside one of the pair of snap rings 18 is then installed, followed by the positioning on the shaft of the rotor 10 and the shaft key 23 being received within the

slots

24 and 25 thereof, and the securing of the rotor against axial displacement on the shaft by installation of the outer snap ring 18. With the rotor in place, the stator 29, having the tubular ring 30 pre-positioned thereon, is placed over the rotor by engaging the same in a circumferential groove 36 on the inside surface of the inner cylindrical part 15. In preconstructing the flow introduction and discharge unit, the tubular ring 30 having the pair of inner projections 31 integrally formed thereon may be positioned over the stator 29 and secured thereon, as by welding the ends of the projections 31 to the cylindrical outside edge of the stator 29, and the outside pair of projections, or collars, 31 are then positioned on the stator 29, one each on each end thereof, whereupon they are secured to the annular ring 30 and to the outside edge of the stator by welding or the like. To complete the assembly, the outer cylindrical part 15 having an upstanding ring-like extension 37 integrally formed on one end face thereof is positioned on the shaft 11, with the extension 37 being snuggly received within the stator 29, and is secured against axial displacement along the shaft by installation of the snap ring 16. Of course, it is to be understood that the other rotor unit 10a shown in FIG. 1 as being disposed on the opposite side of the housing 14 is assembled in substantially the same manner.

Referring now more particularly to FIGS. 2, 3 and 4, it may be observed that the flow being forced through the input 33 and into the central one of the three axially-spaced annular chambers formed between the stator 29 and the tubular ring 30, is directed therefrom through the apertures 34 and the stator 29 at such angles that it passes substantially tangentially over the peripheral edges 38 of the central rotor section 19 between the spaced pockets 20 therein which, as best shown in FIG. 3, are slightly sloped so that the flow thereover is curved radially inwardly to not merely strike the opposite side of the pocket, but to initiate the formation of a vortex flow pattern therewithin. This flow exits from the pockets 20 through the connecting apertures 27 in the outer rotor sections 21, which may be seen in FIG. 4 as essentially lying in chordal planes arranged in an annular pattern about the rotor sections, but being angularly oriented relative to the longitudinal axis thereof. Thus, flow of the gas or steam into the pockets 20 of the central rotor section 19 produces a thrust effect and, in almost simultaneous fashion, a recoil effect in the direction of rotation is produced as the gas or steam flows out through the angularlyoriented chordal apertures 27 in the outer rotor sections 21 into the surrounding chamber to further propel the rotor.

As hereinbefore indicated, the rotors and 10a differ only in that they are oppositely positioned on the shaft 11. That is, the peripheral edges 38 between the pockets of each of the central rotor sections 19 are sloped in opposite directions, as are the apertures 27 in each pair of outer rotor sections 20 and the openings 34 in each stator 29 angled in opposite directions. The inlet and

outlet ports

33 and 35, respectively, are also reversed, so that flow through either one or the other produces rotation of the rotors, and accordingly of the shaft 1 l, in opposite directions. A three-way valve 39 is provided for controlling flow of gas or steam from the source 32 to the inlet of either the rotor 10 or the rotor 10a, as desired, for in turn controlling the direction of rotation of the shaft 11.

With the enhanced efficiency of the turbine apparatus hereinbefore described, produced primarily by the thrust effect of the initial vortex-creating flow in the pockets 20 in combination with the reactive jet effect of the flow through the angularly-oriented chordal apertures 27, a peripheral velocity may be achieved which is extremely slow in comparison to the dimensions of the rotors, without affecting the output of the energy produced thereby. Also, with the present invention, recycling of the steam is readily permitted, thereby further increasing the operating efficiency of the device.

Another feature of the invention, as hereinbefore discussed, involves the disposition of the shaft-supporting bearings outside the area of the turbines themselves. Lubrication of the bearings 12 may be accomplished, as shown in FIG. 1, through a radial bore 40 in the housing 14 which connects with an annular recess 41 in a central bushing 42.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. [t is to be understood, therefore, that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

l. A turbine comprising, in combination with a shaft rotatably journaled in a stationary support:

at least one rotor mounted on said shaft for rotary movement therewith;

said at least one rotor being formed of a central rotor section and a pair of outside rotor sections disposed one each on opposite sides of said central rotor section relative to the axis of said shaft;

means surrounding said at least one rotor forming a closed chamber thereabout; said central rotor section having a plurality of circumferentially-spaced pockets formed in the periphery thereof and said outside rotor sections each having openings therein for providing fluid communication between said pockets and said closed chamber on both axial ends of said rotor;

inlet means in said chamber-forming surrounding means for introducing fluid under pressure into said pockets substantially tangentally to the peripheral portions of said central rotor section between said pockets to provide a thrust and thereby to cause said rotor and shaft to rotate in a given direction; and

outlet means from said chamber-forming surrounding means for permitting fluid to be discharged from the ends thereof on opposite axial sides of said rotor.

2. The turbine set forth in claim 1, wherein said central rotor section and each of said outside rotor sections of said at least one rotor are substantially cylindrical in configuration, and said closed chamber about said rotor also is substantially cylindrical in general configuration.

3. The turbine set forth in claim 2, wherein the peripheral edges of said central rotor section between each adjacent pair of said plurality of pockets therein are slightly sloped inwardly toward the pocket interior, whereby thrust-producing fluid introduced therein is caused to curve radially inwardly and initiate a vortex flow pattern within the pocket.

4. The turbine set forth in claim 3, wherein the openings in said outside rotor sections correspond in number to the pockets in said central rotor section and are angularly oriented in said outer rotor sections in the direction of flow of said fluid being introduced into said rotor for causing a reaction during the passage of said fluid into said closed chamber, which further propels the rotor.

5. The turbine set forth in claim 4, wherein said means surrounding said rotor and forming said closed chamber comprises a substantially tubular stator coaxial with said shaft being closed at both ends and said means for introducing fluid into said pockets comprises a plurality of angularly oriented openings in said stator, said openings being in a plane perpendicular to said shaft and coplanar with said central rotor section, and further comprising means forming a central annular chamber about said stator substantially coplanar with said central rotor section through which fluid may be introduced to said angularly oriented stator openings and means forming a pair of annular chambers about said stator being axially spaced by said central annular chamber and being open through said stator to the sides of said closed chamber formed thereby on opposite axial sides of said rotor into which fluid may be discharged from said closed cylindrical chamber.

6. The turbine set forth in claim 5, further comprising:

means for introducing fluid under pressure into said central one of said spaced annular chambers, and means for discharging fluid from said outside ones of said spaced annular chambers.

7. The turbine set forth in claim 1, further including means for preventing relative rotation between said central rotor section and said outside rotor sections, and for causing concurrent rotation of said central rotor section and said outside rotor sections with said shaft.

8. The turbine set forth in claim 7, further including means for preventing axial displacement of said central rotor section and said outside rotor sections on said shaft.

9. The turbine set forth in claim 3, wherein said at least one rotor includes a pair of said rotors mounted on said shaft in spaced relation, said rotors being inversely disposed on said shaft with said inlet means of the one rotor being angularly displaced about the shaft axis with respect to the inlet means of the other rotor and the peripheral edges between the pockets of the central rotor section of the one rotor being sloped inwardly in opposite circumferential direction than the peripheral edges between the pockets of the central rotor section of the other rotor, such that the introduction of fluid in one of said rotors causes rotation of said shaft in one direction and the introduction of fluid into the other said rotors causes rotation of said shaft in an opposite direction.

10. The turbine set forth in claim 9, further including valve means connected with said pair of rotors and adapted to be connected to a source of fluid under pressure for controlling the introduction of said fluid either to one or the other of said rotors.

11. The turbine apparatus set forth in claim in combination with a steam generator.

12. The turbine set forth in claim 1, wherein said at least one rotor includes a pair of said rotors mounted on said shaft in spaced relation, and further being characterized by:

said central rotor sections and each of said outside rotor sections of each of said pair of rotors being substantially cylindrical in configuration;

each of said closed chambers about each of said rotors comprising a pair of substantially cylindrical chambers disposed one each on either axial side of each of said rotors;

the inlet means of the one rotor being angularly displaced about the shaft axis with respect to the inlet means of the other rotor;

the peripheral edges between each adjacent pair of said plurality of pockets of the central rotor section of the one rotor being slightly sloped inwardly in one circumferential direction toward the interiors of the pockets thereof and the peripheral edges between each adjacent pair of said plurality of pockets of the central rotor section of the other rotor being slightly sloped inwardly in opposite circumferential direction toward the interiors of the pockets thereof, whereby thrust-producing fluid introduced therein is caused to curve radially inwardly in opposite circumferential directions and initiate vortex flow patterns within the pockets of each of the central rotor sections, such that the introduction of fluid in the one of said rotors causes rotation of said shaft in one direction and the introduction of fluid into the other of said rotors causes rotation of said shaft in an opposite direction;

the openings in said outside rotor sections corresponding in number to the pockets in said central rotor sections and being angularly oriented in an annularly disposed series of chordal planes in said outer rotor section in the direction of flow of said fluid being introduced into said rotors for causing a reaction during the passage of said fluid into said closed chambers, which further propels the rotor;

said means surrounding each of said rotors and forming said closed chambers comprising a substantially tubular stator being closed at both axial ends and said means for introducing fluid into said pockets comprising a plurality of angularly oriented openings in said stator, being oriented substantially in one circumferential direction in the one rotor and in an opposite circumferential direction in the other rotor;

means forming an annular chamber about each of said stators through which fluid is introduced to said stator openings and into which fluid is discharged from said cylindrical chambers, each comprising a series of axially spaced separate chambers, the central one of which communicates with said openings in said stator and the other ones of which communicate respectively with said pair of cylindrical chambers disposed axially on the sides of each of said rotors;

means for selectively introducing fluid under pressure into one or the other of said central one of said series of spaced annular chambers; and

means for discharging fluid from said outside ones of said spaced annular chambers.

1! i i I t

Claims

1. A turbine comprising, in combination with a shaft rotatably journaled in a stationary support: at least one rotor mounted on said shaft for rotary movement therewith; said at least one rotor being formed of a central rotor section and a pair of outside rotor sections disposed one each on opposite sides of said central rotor section relative to the axis of said shaft; means surrounding said at least one rotor forming a closed chamber thereabout; said central rotor section having a plurality of circumferentially-spaced pockets formed in the periphery thereof and said outside rotor sections each having openings therein for providing fluid communication between said pockets and said closed chamber on both axial ends of said rotor; inlet means in said chamber-forming surrounding means for introducing fluid under pressure into said pockets substantially tangentally to the peripheral portions of said central rotor section between said pockets to provide a thrust and thereby to cause said rotor and shaft to rotate in a given direction; and outlet means from said chamber-forming surrounding means for permitting fluid to be discharged from the ends thereof on opposite axial sides of said rotor.

6. The turbine set forth in claim 5, further comprising: means for introducing fluid under pressure into said central one of said spaced annular chambers, and means for discharging fluid from said outside ones of said spaced annular chambers.

11. The turbine apparatus set forth in claim 10 in combination with a steam generator.

12. The turbine set forth in claim 1, wherein said at least one rotor includes a pair of said rotors mounted on said shaft in spaced relation, and further being characterized by: said central rotor sections and each of said outside rotor sections of each of said pair of rotors being substantially cylindrical in configuration; each of said closed chambers about each of said rotors comprising a pair of substantially cylindrical chambers disposed one each on either axial side of each of said rotors; the inlet means of the one rotor being angularly displaced about the shaft axis with respect to the inlet means of the other rotor; the peripheral edges between each adjacent pair of said plurality of pockets of the central rotor section of the One rotor being slightly sloped inwardly in one circumferential direction toward the interiors of the pockets thereof and the peripheral edges between each adjacent pair of said plurality of pockets of the central rotor section of the other rotor being slightly sloped inwardly in opposite circumferential direction toward the interiors of the pockets thereof, whereby thrust-producing fluid introduced therein is caused to curve radially inwardly in opposite circumferential directions and initiate vortex flow patterns within the pockets of each of the central rotor sections, such that the introduction of fluid in the one of said rotors causes rotation of said shaft in one direction and the introduction of fluid into the other of said rotors causes rotation of said shaft in an opposite direction; the openings in said outside rotor sections corresponding in number to the pockets in said central rotor sections and being angularly oriented in an annularly disposed series of chordal planes in said outer rotor section in the direction of flow of said fluid being introduced into said rotors for causing a reaction during the passage of said fluid into said closed chambers, which further propels the rotor; said means surrounding each of said rotors and forming said closed chambers comprising a substantially tubular stator being closed at both axial ends and said means for introducing fluid into said pockets comprising a plurality of angularly oriented openings in said stator, being oriented substantially in one circumferential direction in the one rotor and in an opposite circumferential direction in the other rotor; means forming an annular chamber about each of said stators through which fluid is introduced to said stator openings and into which fluid is discharged from said cylindrical chambers, each comprising a series of axially spaced separate chambers, the central one of which communicates with said openings in said stator and the other ones of which communicate respectively with said pair of cylindrical chambers disposed axially on the sides of each of said rotors; means for selectively introducing fluid under pressure into one or the other of said central one of said series of spaced annular chambers; and means for discharging fluid from said outside ones of said spaced annular chambers.