US2477798A

US2477798A - Contrarotating axial flow high and low pressure turbine and compressor with bladed duct with turbine cooling

Info

Publication number: US2477798A
Application number: US505389A
Authority: US
Inventors: Griffith Alan Arnold
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 1941-04-08
Filing date: 1943-10-07
Publication date: 1949-08-02
Anticipated expiration: 1966-08-02

Description

1949- A. A. GRIFFITH 2,477,793

CONTRA ROTATING AXIAL FLOW HIGH AND LOW PRESSURE TURBINE AND COMPRESSOR WITH BLADED DUCT WITH TURBINE COOLING Flled Oct '7, 1943 5 Sheets-Sheet 1 Glam/ M Aug. 2, 1949.

TURBINE AND COMPRESSOR WITH BLADED DUCT WITH TURBINE COOLING 5 Sheets-Sheet 2 Filed Oct. 7, 1943 I INYEIVTOA I M 5% :L

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flTTOR/VEY 1949- A. A. GRIFFITH 2,477,798

CONTRA ROTATING AXIAL FLOW HIGH AND LOW PRESSURE TURBINE AND COMPRESSOR WITH BLADED DUCT WITH TURBINE COOLING Filed 001;. 7, 1943 5 Sheets-Sheet 3 1949- A. A. GRIFFITH 2,477,798

CONTRA ROTATING AXIAL FLOW HIGH AND LOW PRESSURE TURBINE AND COMPRESSOR WITH BLADED DUCT WITH TURBINE COOLING Filed Oct. 7, 1945 5 Sheets-Sheet 4 ALA/V A. GRIFFITH wmmw m Filed 00 1945 1949- A. A. GRIFFITH 2,477,798

CONTRA ROTATING AXIAL FLOW HIGH AND LOW PRESSURE TURBINE AND COMPRESSOR WITH BLADED DUCT WITH TURBINE COOLING 5 Sheets-Sheet 5 ALAN A Game/TH (DMMH' tions.

Patented Aug. 2, 1949 LOW PRESSURE TURBINE AND COM- PRESSOR WITH BLADED DUCT WITH TUR- BIN E COOLING Alan Arnold Griffith, Derby, England, assignor to Rolls-Royce Limited, Derby, England, a British company Application October '7, 1943, Serial No. 505,3 89

In Great Britain April 8, 1941 Section 1, Public Law 690, August 8, 1946 Patent expires April 8, 1961 (C1. (SO-35.6)

12 Claims. 1

capable of individual rotation so that their speeds are inherently adjustable to suit wide variations of working conditions, the construction being particularly applicable to internal-combustion turbines or hot-air turbines. Preferably the alternate rotor elements rotate in opposite direc- This invention comprises a turbine power plant of the kind described, wherein some 'at least of the rotatable bladed elements of the turbine and turbo-compressor supplying it, carry also each an airscrew to constitute therewith a unitary rotary element.

The invention also comprises the use of such a power unit as the propulsion means for an aircraft, and according to another feature of the invention the airscrew or airscrews are mounted in a tunnel surrounding the turbine and its compressor. Where multiple airscrews are used, they may rotate in opposite directions.

In a preferred form of the invention, the power unit comprises two sets of rotor elements, one set carrying compressorand turbine-blades and the other set, at the exhaust end of the turbine, carrying compressor-blades, turbine-blades and airscrews.

According to yet another feature of this invention, there is provided for a power unit as above set forth, a supporting structure or framing comprising a two-part cylindrical casing whereof one part constitutes an open-ended annular tunnel wherein the airscrews operate, and the other encloses the remainder of the rotor elements, a fixed central shaft whereon the rotor elements are mounted, and radial arms supporting said shaft in said casing.

According to another feature of the invention, the structural members aforesaid, or some of them, are hollow and means are provided for circulating cooling air through them.

According to another feature of this invention, any. accessory elements for the engine, or for an aircraft wherein it is mounted, which require a drive, are driven by suitable compressedair motors deriving their supply from the main compressor.

In the accompanying drawings. which are purely diagrammatic, there is illustrated one embodiment of this invention constituting a power unit for the propulsion of aircraft.

In these drawings:

Figure 1 is an elevation in section on the line l-| of Figure 3,

Figure 2 is a plan partly in section on the line 22 of Figure 1,

Figure 3 is a view looking from the right in section on the line 3-3 of Figure 1 with certain parts omitted,

Figure 4 is a half section on the line 44 of Figure 1,

Figure 5 is a section on the line 5-5 of Figure 4,

Figure 6 is a section on the lines 66 of Figures 1 and '7, and

Figure 7 is a section on the line 'l-| of Figure 6.

Figure 8 is a fragmentary vertical section taken from the upper portion of Figure 9.

Figure 9 is a fragmentary perspective view with parts broken away and parts shown in section of a high pressure turbine and compressor con- :tructed in accordance with the present invenion.

These drawings represent diagrammatically a power-unit mounted on the wing of an aircraft, the wing being indicated by the reference I0. On the wing there is mounted in any convenient manner an open-ended tunnel-like structure il into the rear end l2 of which the leading edge of the wing protrudes. From the casing ii there project radially inwards two sets of radial arms I 3, M, respectively, these arms being streamlined longitudinally of the casing, and for the purpose hereinafter described they are hollow.

The forward set of arms l4 supports a second part l5 of the main casing of the power unit, this part extending forwardly from them, and the two sets of arms jointly support directly or indirectly acentral stationary shaft I6.

Upon the shaft is there are mounted two sets of rotor elements which are individually of general disc-like formation and are mounted on-separate bearings so as to be rotatable independently of one another; suitable thrust-bearings are provided between the rotor elements.

The after set of rotor elements indicated generally by the reference I! each comprises a central portion i8 (Figures 1, 4 and 5) carrying a.

shroud-ring l9 on which there are supported aircompressor blades 20. Around the periphery of these blades there extends a second shroud-ring 2| which carries turbine blades 22 with an outer shroud-ring 23 which in turn carries airscrewblades 24. Theseblades 24 are shown in Figs. 1 and 2, but have been omitted from Fig. 3 in order not to obscure other parts of the structure.

The set of rotor elements I! constitutes the low-pressure end of the turbine and compressor,

' l2 thereof.

and a second set of elements indicated by the reference 25 which are situated within the casing constitute the high-pressure end of the unit. The elements are similar to the elements l1 except that they carry only compressor blades 26 and turbine blades 21; they do not carry airscrew blades. The forward elements 25, being at the high-pressure end of the power unit, are of smaller diameter than the after set of elements l1, and suitable ducts 28, 29 are provided to establish communication between the turbine blades and the compressor blades, respectively, of the two sets of rotor elements. When the power unit is in operation, air is taken in, as hereinafter described at the after or, as viewed in Figure 1, left-hand end of the compressor and travels towards the right through the low-pressure blades 20, the connecting conduit 29 and the high-pressure blades 26, and is delivered at 30 under a. suitable high-pressure to the interior of a combustion chamber 3|. Fuel is supplied to the high pressure air in the combustion chamber 3| through nozzles 5| (Figures 6 and '7) mounted on a fixed tubular support 52 and is burnt in the air. The products of combustion are delivered to the space 32 which communicates with the forward end of the high-pressure set of turbine-blades 21 and the gases travel rearwardly therefrom and through the conduit 28 to the low-pressure turbine-blades 22, being finally delivered at the rear end 33 into the interior of the casing II where they mix with the slipstream from the airscrewblades 24, being finally discharged to atmosphere therewith through the open rear end l2 of the casing H.

The air-supply to the compressor is taken from the tunnel ll within which the airscrewblades operate, as shown most clearly in Figure 2.

Referring first to Figures 1, and 2, the leading edge of the wing, which is indicated at 34, is shortened as shown at 35 where it lies within the casing H, and two air-inlet ducts, shown most clearly in Figure 2 at 36, are disposed one on each side of the power-unit opposite the airscrew-blades so as to take advantage of the pressure derived therefrom as a pre-compression of the air prior to its entering the compressor proper. These inlets 36 communicate by a conduit 31 with an annular chamber 38 (see Figure 2) which is provided at its forward or, as viewed in Figure 2, right-hand side with an annular port 33 aligned with the intake end of the compressor, to deliver air thereto. The remainder of the slipstream from the airscrews passes around the intake ports 36 and over the shortened nose 35 of the wing into the upper and lower parts of the tunnel H to be discharged at the rear end Similarly, the exhaust gases discharged at 33 from the turbine pass outwards beside the annular air port 39 into the slipstream from the airscrews, as mentioned above.

The cooling of the structure, and particularly of the high-pressure end of the turbine and compressor, is effected in the following manner. The supporting arms i3, H, as stated above, are made hollow and air from the slipstream of the airscrews is admitted by openings 40 on the leading edge of the rear set of arms l3 to the interior thereof and, travelling radially outward. is conveyed by a duct 4| to the interior of the forward set of arms l4 and radially inwards to the neighborhood of the casing 42 of the forward end of the turbine. This casing is finned, as shown at 43, and the air is delivered from each of the arms H to an annular chamber 44. From this chamber 44 the air is taken by ducts 45 which extend forwardly over a part of the finned length of the casing, and these ducts are open on their inner side to admit the air to the inter-fin space so that it travels circumferentially in each direction to neighborhood ducts 46 which are somewhat longer than the ducts 45. The air escapes from the ducts 46 inwards again into the interfin space and travels circumferentially to the exposed part of the fins 41 beyond the ends of the ducts 45, whereat it escapes into the interior of the casing l5 and to atmosphere through an opening 48 in the forward end thereof or in any other convenient manner. It will'be appreciated that since the initial supply of cooling air is taken from the slipstream of the airscrews there is adequate pressure-difference to deliver the air in this manner from the nose of the cowlin or casing I5. The discharge of heated air from the nose of the cowling so that it passes over the surface thereof may be advantageous in reducing the drag.

In the preferred construction of this powerunit there are no stationary blades for the rotary compressor or for the turbine except at the inlet end of each, that is to say in the inlet port 39 for the air and in the port opening from the chamber 32 to the turbine blades. Instead, the turbine blades 22 (see Fig. 5) on each rotor element are oppositely disposed to those on the adjacent elements so that they rotate in opposite directions and the compressor blades 20 are correspondingly disposed.

The starting of the power-unit may be effected by a small auxilia'ry' blower situated, for example, in the casing 32 adjacent the burner and driven by an electric or other motor 43 to deliver compressed air to the turbine blades. As shown in Figures 6 and 7 the blower comprises a disc 53 mounted on the shaft 54 of the motor and carrying radial-flow blades 55. This device is required to provide only a comparatively small quantity of air at a comparatively low pressure, since when this blower is started, and the burner lighted, a. supply of the products of combustion delivered to the turbine sets it in motion and as soon as it is in motion the main compressor becomes operative to increase the pressure and volume of the air-supply so that the turbine rapidly accelerates to its normal working speed. The control of the power-unit during operation is effected by controlling the fuel-supply to the burner.

I claim:

1. A turbine power plant comprising a plurality of rotor elements each carrying a ring of turbine blades and a ring of compressor blades disposed one ring within the other in the same axial plane and mounted to rotate independently about a common axis to form an axial flow turbine and an axial flow air-compressor driven by the turbine, a combustion chamber into which the air-compressor delivers the compressed air and which communicates with the intake to the turbine. a fuel-burner in the combustion chamber, and a plurality of airscrews mounted each on a different one of the rotor elements in the same axial plane as the rings of blades to rotate therewith.

2. A turbine power plant according to claim 1, wherein the turbine blades and compressor blades on each rotor element are oppositely disposed to those on the adjacent rotor elements so that adjacent rotor elements rotate oppositely.

3. A turbine power plant according to claim 1,

comprising an annular casing coaxial with the rotor elements and surrounding the rotor elements carrying the airscrews to form a tunnel within which the airscrews rotate.

4. A turbine power plant comprising a set of rotor elements each carrying coaxial turbine blades and compressor blades and mounted to rotate independently about a common axis to form a low-pressure turbine and a low pressure aircompressor driven by the turbine, a plurality of airscrews mounted each on the periphery of a different one of said rotor elements to rotate therewith, a second set of rotor elements each carrying coaxial turbine blades and compressor blades and mounted coaxially of the first set of elements to rotate independently and to form a high-pressure turbine and a high-pressure aircompressor driven by the latter turbine, means conveying compressed air from the low-pressure air-compressor to the intake of the high-pres sure air-compressor, a combustion chamber to which the high-pressure air-compressor delivers compressed air and which communicates with the intake to the high-pressure turbine, a fuel burner in the combustion chamber, and means for conveying the products of combustion from the high-pressure turbine to the intake of the low-pressure turbine.

5. A turbine power plant according to claim 4 comprising a two-part cylindrical casing of which one part encloses the second set of rotor elements and the other part is of larger diameter and encloses the airscrews to form a tunnel wherein the airscrews rotate, a fixed central shaft whereon rotate, two sets of hollow arms extending radially inwards from the second part of the casing at either end of the airscrew assembly and the first set of rotor elements and supporting the shaft and of which radial arms some of those located on the slip-stream from the airscrews are formed with air-intakes facing the airscrew assembly, ducts conveying air entering said intakes from the radial arms in which the ducts are provided to the first part of the casing to cool the rotor elements therein.

7. A turbine power plant according to claim 4, comprising an externally finned casing wherein the second set of rotor elements rotate, an outer casing enclosing and spaced from the finned casing, and means for circulating cold air through the space between said casings to cool the finned casing and, thereby, the rotor elements it encloses.

8. A turbine power unit according to claim 4, comprising an externally finned casing enclosing the second set of rotor elements, a plurality of ducts extending lengthwise of the said casing and open at one side to the inter-fin spaces of the casing, and means for supplying cold air to said ducts and thence through the inter-fin spaces of the said casing.

9. A turbine power plant according to claim 4, comprising a casing enclosing the second set of rotor elements and formed externally with circumferential cooling fins, two intercalated sets of ducts extending longitudinally of, and surrounding, the said casing, each of which ducts is open at one side to the inter-fin spaces of the said casing and communicates with the adjacent ducts through said inter-fin spaces, and of which the ducts in one set extend the full length of the said inwards from the casing at each end thereof, a

shaft carried by the inner ends of said arms to extend coaxially through and from the forward end of the casing, a set of rotor elements individually rotatable on said shaft within the casing and carrying each a set of turbine blades, a set of air-compressor blades and an external set of airscrew blades, which set of rotor elements forms a low-pressure turbine, driving a low-pressure airvcompressor and a set of airscrews, a second set of rotor elements mounted to rotate of the shaft forwardly of the casing and carrying each a set of turbine blades and a set of air-compressor blades to form a high-pressure turbine and a high-pressure air-compressor driven thereby, means conveying compressed air from the lowpressure air-compressor to the high-pressure aircompressor, a combustion chamber to which the latter air-compressor delivers and which communicates with the high-pressure turbine, a fuel burner in the combustion chamber, means conveying the products of combustion from the highpressure turbine to the low-pressure turbine, an externally finned casing enclosing the second set of rotor elements, means enclosing the finned casing and providing ducts for cooling air which communicate with the interior of some at least of the radial arms and extend over and open to the finned casing to outlets, ducts in the annular casing providing communication between the interiors of the said radial arms and the interiors of radial arms at the rearward end of the annular casing which latter arms are formed with air-intakes facing forwardly in the slipstream of the air-screws.

11. An internal combustion power plant for propulsion in air comprising in combination, a propelling nozzle, a high pressure axial flow combustion air compressor, a combustion chamber connected to receive combustion air from the compressor and to discharge products of combustion rearwardly therefrom, turbine stages driving said compressor, an annular duct in which said turbine stages are located, said duct communicating with the propelling nozzle for the fiow thereto of the rearwardly discharging products of combustion from the combustion chamber, independently rotatable lower pressure contra-rotating axial flow turbine blading stages also disposed in said duct beyond said first named stages in the direction of fiuid flow, two rotors on which said last named stages are mounted, rows of axial flow low pressure air blading carried by said rotors and disposed radially outwardly of said second named turbine blading, rows of axial flow low pressure air blading also carried by said rotors and disposed radially inwardly of said second named turbine blading, an air duct in which said first named low pressure air blading is disposed and having communication with the propelling nozzle, and an air duct in which said last named low pressure air blading is disposed and in communication with said compressor," in which the outer low pressure air blading eflects preliminary compression of the combustion air and the inner low pressure air bladin constitutes one element oi a contra-rotating low pressure combustion air compressor and including an air duct connecting said outer and inner low pressure a-ir bladings.

12. An internal combustion power plant for propulsion in air comprising in combination, a propelling nozzle, a high pressure axial flow combustion air compressor, a combustion chamber connected to receive combustion air from the compressor and to discharge products oi combustion rearwardlytherefrom, turbine stages driving said compressor, an annular duct in which said turbine stages are located, said duct communicating with the propelling nozzle for the flow thereto of the rearwardly discharging products of combustion from the combustion chamber, independently rotatable lower pressure contra-rotatin axial flow turbine blading stages also disposed in said duct beyond said first named stages in the direction of fluid flow, two rotors in which said last named stages are mounted, rows of axial flow low pressure air blading car- REFERENCES CITED The following references are of record in the tile of this patent:

UNITED STATES PATENTS Number Name Date 1,279,128 Lake Sept. 17, 1918 2,050,349 Lysholm Aug.11, 1938 2,168,726 Whittle Aug. 8, 1939 FOREIGN PATENTS Number Country Date 541,349 Great Britain; Nov. 24, 1941 358,570 France Dec. 22, 1905, 817,065

France May 15, 1937