US2646209A - Turbine driven multistage compressor - Google Patents

Description

J. A. N. GALLIOT TURBINE DRIVEN MULTISTAGE COMPRESSOR 2 Sheets-Sheet 1 July 21, 1953 Filed May 18, 1949 Jules Andr a Norberl Galliol y 1, 1953 J. A. N. GALLIOT TURBINE DRIVEN MULTISTAGE COMPRESSOR 2 Sheets-Sheet 2 Filed May 18, 1949 ITnfenEw Juies Andre Nor-her! Gallz'ot M y m c I Iorngys Patented July 21, 11 953 TURBINE DRIVEN MULTISTAGE COMPRESSOR Jules Andre Norbert Galliot, Bexley, England Application May-18, 1949, Serial No. 98,922 In France May 21; 1948.

This invention relates to gas turbines such as employed for jet-propelled aircraft and like pur-' poses."

The invention relatesmore particularly to gas turbines as described in my pending patent application Serial No. 730,446, filed February 24,

6 Claims. (01. 230-116) turbine.

1947, Patent No. 2,60i),235, issued June 10, 1952.

The main objects of the present invention are to provide means for obtaining higherpoweroutput from the turbine and to reduce theweight of the rotating parts.

More specifically, the invention has for object to lighten the turbine rotor by making it of a light alloy having a specific weight or density of about 4 or less, the-use of such material being made possible by intensive cooling of the turbine blades and connected parts.

Another object is to provide for higher compression of the air delivered to the combustion chambers, by arranging'for multi-stage compression preferably with inter-stage cooling and with final heating of the compressed air supplied to the combustion chambers. 1 r

Other objects and advantages of the invention will hereinafter appear from the followingfde scription, given with reference to the accompanying drawings, in which:

Fig. 1 is a diagrammatic viewof one half being in longitudinal section andthe other half in elevation. v i Fig. 2 is an enlarged end view froin'the left of Fig. 1, with parts broken away on the right to show the interior of one compressor andits outletconnecti'ons, and" on the left to show the interior of the other compressor and ,itsconnec tions.

Fig. 3 is a half-section of the centrifugal compressors at one end of the turbine.

Fig. 4 is a perspective view of one of the turbine blades with the associated vane element of a primary compressor.

Fig. 5 is a sectional detail and wheelspoke. V

Referring to Fig. 1, theturbine shaft If} is fitted at one end with a driving wheel H having external blades 12 against which hot gases are directed by guide vanes IS, the gases being delivered from combustion. chambers l4 spaced around the shaftand extending approximately of the turbine blade parallel to its axis. The central portion ofthe turbine wheel I l is apertured by providing it with spokes or webs which are shaped as helicoidal the turbine,

similarly enlarged view showing a turbine wheelfrom the interior of an outer cas-- ing 16, the open end ll of which faces the direction of flight of the aircraft driven by the Within the casing, the cold incoming air passes between and along the outside of the combustion chambers hi to the rear end'of the casing, where it is deflected inwardly to pass between a plurality of ducts lilconveying the exhaust gases from the turbine to the jet outlet 19. v The air passages are preferablyof oval or streamlined sectionto allow the deflected air to flowfreely between-the ducts lB'and substantially in'a radial direction, after which the air travels forwards through a'fixed grid 28 including annular guide vanes to the rotating vanes l5. After passing through the latter, the air encounters another set of guide-vanes 2| formed by radial arms supporting the'turbine stator 22,

these vanes or arms and thefixed grid 2!] carrying bearings 23 forthe shaft l0.- 7 Beyond the guide vanesZI there is arranged a multi-stage axial-flow compressor composed of alternate rotor blades 24 secured to rings 25 fixed I I onthe shaft l0 and stationary blades 26 fixed inside an induction tube'2'l, the outer wall of which is insulated against the heat of the 'com-.

bustion chambersf'M by inserts 28 of suitable material. compressor blades 24, '26 being-of gradually decreasing height until near the forward end of the tube, where the last set of'stationary blades 26 are shaped to give a sharper taper whereby the-partly compressedair is led into the eye or intake 29 of a centrifugal compressor 3G secured upon the shaft; this compressor 39 has its runner madeintegral with that of another centrifugal compressor 3 l, the two runners being placed ing of the main compressor -30 and are then curved over forwardly and inwardly towards the intake 33 of the othercompressorfwhere the gases enter with a tangentially velocity component; these relatively long'branches 35 may bemade initwo lengths connected by flanged joints The tubeZ'l tapers in diameter, the

36 to facilitate manufacture and erection, and the exposed lengths leading to the intake 33 are preferably ribbed externally or provided with gills 31 or the like (as shown in Fig. 2, in one instance) for cooling purposes.

The final compressor 3|, being supplied with air already compressed in the previous stages and preferably cooled as stated before transfer to this final stage, can be made of smaller capacity and of a diameter considerably less than the main compressor; the manifold 34, into which the finally compressed air, is. delivered, can therefore be of smaller diameter at the joint-- ing surfaces 38 than the first manifold 32: see Fig. 3. This second manifold intakev 34. is con veniently made of toroidal annular, shape, as seen more clearly in Fig. 2 with alternate inlets 39 and delivery branches 40 respectively, ar-

ranged obliquely to its cross-section, as seen in.

Fig. 3; thus the compressed air passing through ittravels for a short distance circumferentially from. each inlet 39. to, the next delivery branch 49, and with a helicoida-l swirling motion inside the manifold. The delivery branches or connectors 40 of this second manifold will extend more or less tangentially and in the samev direction around the axis of the shaft It] as the branches 35 from the main compressor 30, but in a different plane, so that as they curve over rearwardly of the aircraft to connect with the respective combustion chambers l4, they can be located alternately between the'respective forwardly curving branches 35 of. the first manifold, the two sets of branches 35; 40- thus crossing without interference. The air may be caused to slow down inside the second manifold by increasing the cross-sectional area of. the latter relative to the area of the inlets: 39', thereby converting part of its kinetic energy into pressure.

Within the second manifold: 34,. and: extending either continuously'orat intervals; around its circumference, suitable heating means are pro vided, for example in the. form of an: electrical and is also heated by the electrical resistor coil 4| before delivery from the branches 48 leading into the respective combustion chambers, these branches being heat insulated to retain the heat of the air; as the heating is applied to pure air, there is no danger of ignition within the manifold 34 or its branches 40.

The increase of pressureof the. compressed air reduces the overall size or bulk of the combustion chambers and turbine, and also leads to fuel economy suflicient to olfset the small amount of energy consumed in heating the air within the second manifold 34, which is kept as hot as possible by external lagging (not shown). Fuel is suppliedto the-combustion chambers l4 through injectors of known kind (not shown), the supply of, fuel being effected by the auxiliary mechanism 50 indicated in Fig. 1.

The number of branches of both manifolds 32, 34 will be made equal to the number of combustion chambers M to be supplied, for example nine, so that the branches of each manifold can be inter-spaced between those of the other, the delivery branches 40 of the secondv manifold crossing the first manifold at the points between its branches 35. The air from the main compressorifl has its temperature lowered by the inter-stage cooling effected by the ribbed or gilled branches 35- of the first manifold which is kept as cool as possible; these branches are preferably cooled by the air entering the casing is, this air being thus slightly pre-heated so as to reduce the risk of icing up the primary compressor.

It will be understood that the above-mentioned values of the compression in the various stages are given merely by Way of example and that the proportional values of the three stages resistor such as a coiled wire 4!, as shown on the left of Fig. 2; this resistor coil may be raised to red heat by passage of a current supplied by a generator (not shown) driven by the turbine.

Assuming that the atmospheric air entering by ram effect into; the open end '21 of thecasing,

and preheatd slightly by the combustion chainpressor 30, the latter canbe designed to raise V the compression to about 3. atmospheres, instead of the more usual pressure of about 4 atmospheres required for feeding the combustion chambers 14; the main compressor can thus be made of smaller size than if it had to produce the final pressure. The air delivered by this main compressor 30 is then conveyedthrough the connected manifold 32 and its branches 35 to the eye or intake of the other compressor 31 mounted in front of the former; this other compressor 3|, being supplied with air at a pressure of 3% atmospheres, can be made of still smaller diameter, while serving to compress the air to a final pressure of about 5. atmospheres for feeding the combustion chambers [-4. This air is conveyed through the second manifold 34, wherein it is allowed to slow down; slightlyso as to convert part. of its kineticv energy into, pressure,

of compression may also be varied.

The turbine rotor, comprising the driving wheel H, the rotating blades 24 of. the axialfiow compressor, and the main and final compressors 38, 3|, are made of-a light. alloy having a specific weight preferably lower than 4, as compared with the specific weight of about 8 in the case of austenitic steel and alloy steels with a high nickel-content, as hitherto employed, which steels are comparatively poor conductors of heat. Among the light alloys to be used, there may be mentioned Hidum-iniumg of a specific weight of 2.85, capable of withstanding a temperature of 400 C., and possessing excellent thermal conductivity, the particular alloy preferred being that known as RR-57, an alloy of outstanding merit for use at temperatures in therange 2'75-400 C., and having the following chemical composition:

Copper Silicon 0.2% max. Iron 0.3% max. Manganese 0.2-0.3% Titanium, 0.1-0.15% Aluminum Remainder the turbine ,wheel ,or otherwise forcibly cooling the rim, blades and central portion or'spokes.

In the present case; the incoming air entering through the turbine wheel ll, after preliminary heating inside the casing Iii, by contact; with the combustion chambers l4'and-exhaustdii'cts [8, will have a temperature lower than- 200 C., so that it is capable of effectively cooling "the wheel by means of the vane-forming spokes or webs I5. Moreover, this air is subject. to centrifugal force inside the wheel H, causing it to press against the interior of the rim connecting the vanes [5 to the external turbine blades l2; by forming air passages withinatheseblades to admit the air from the interior of the wheel, the air can be-made'to flow outwardly through the blades in sufficient quantity to maintain their temperature at or below the .safe working figure of 400 C.

Fig. 4 illustrates one of the turbine wheel spokes comprising the turbine blade I2, the primary compressor vane I5, a connecting segment 42 of the wheel rim, and a root element 43 of wedge shape having teeth 44 whereby the several spokes are rigidly clamped together at the wheel hub in the assembled position, as seen in Fig. ,1. The rim segments are formed with alternate mortises and tenons 45, 46, which interengage with those of the adjacent segments, and are grooved at 41 to receive'clamping rings 48 or the like. A number of holes 49 are drilled longitudinally through the turbine blade l2, so as ploy light alloys which could not otherwise withstand the heat of the gases from the combustion chambers i l, but also secures other accessory advantages.

For example, the construction of thejturbine rotors from light alloys, owing to the reduction of weight which it involves, allows of improving greatly the accuracy of aim when firing guns mounted upon single-seater aircraft. Upon the latter, which are generally unstable at high speeds, the gyroscopic effect due to the turbine rotors produces undesired oscillations,a circumstance which renders it difficult to maintain direction of flight within a few seconds of angle forfiring the gun during thefugitive moments when the target comesinto the line of fire. The gyroscopic effect is in practice greatly reduced owing to the reduction of mass of the rotors constructed in conformity with the invention.

The invention canbe applied for example to the rotors of gas turbines such as describedinmy pending patent application Serial No. 730,446,

in United States Patent No. 2,600,235, in which guide vanes "co-operating with saidspoke-form ingvanes and a plurality of axial-compressor rotors in'series with said primaryistage, and as intermediate and final compression stages two centrifugal compressors'mounted on said 'shaft and operating inseries, atubular casing :around said shaft conveying air from said priinary' compression stage to said intermediate compression stage, and a plurality of tubular connectors in parallel conveying air between said intermediate and final compressionstages.

2. Ina gas turbine including a rotary shaft anda bladed wheel secured thereon, a multistage air-cornpre'ssor comprising as primary and operating in-series, a tubular*caSing' ai'ound said shaft conveying 'air from said primary compression stage to said intermediate compression stage, and a plurality of tubular connectors in parallel conveying air between said intermediate and final compression stages, and means for guiding said air into external contact with said connectors before being admitted to said primary compression stage.

3' In a gas turbine including a rotary shaft and a bladed wheel secured thereon, a multias intermediate and final compression stages two centrifugal compressors mounted on said shaft and operating in series, a tubular casing around said shaft conveying air from said primary compression stage to said intermediate compression stage, and a plurality of tubular connectors in parallel conveying air between said intermediate and final compression stages, external cooling gills upon said connectors, means for guiding air into contact with said gills before admission to I said primary compression stage, a manifold receiving air from said final compression stage, and a plurality of branches being equal in numher to said connectors and also from said manifold conveying the finally compressed air, said branches being interspace'd angularly between said connectors.

4, In a gas turbine including a rotary shaft and a bladed wheel secured thereon, a multistage air-compressor comprising as primary compression stage a plurality of helicoidal vanes forming spokes of said wheel, with stationary guide vanes (Io-operating with said spoke-forming vanes, and as intermediate and final comturbines the greater part or the. whole of the cold air' admitted forcompression to feed the combustion chamber or chambers is caused to pass through the rotorwith a view to increasing the cooling of the latter.

' stage air-compressor comprising as primary compression stage a plurality of helicoidal vanes forming spokes of said wheel, with stationary It is however to be understood'that the invention is not limited to pression stages .two centrifugal compressors mounted on said shaft and operating in series. a tubular casing around said shaft conveying air from .said primary compression stage to said intermediate compression stage, and a plurality of tubularfconnectors' in parallel conveying air between said intermediate and final compression stages, external cooling gillsupon said connectors, means for guidingair into contact with said gills beforeadmission to said primary compression stage, a manifold. receiving air from said final compression stage, and a plurality of branches from said manifold, conveying the 7 finally compresseq air, said connectors. being curved over the exterior? of. said manifeld. and said branches. being equal; in number to said eonnecters, and also being interspaced angularly between said; connectors.

5. In a gas turbine including; a rotary: shaft,

a. bladed wheelsecured thereon, and a multi-,

stage. air-compressor as specified in, claim 1, a turbine Wheel made of a light aluminum alloy of high thermal conductivity, said wheel having its blades integral. with. its spoke-forming;- vanes, and said. vanes: being exposed to the air traversing aid: primary cempression st e- 6. In; a gas turbine including; a rotary shaift. a bladed, wheel. se ured thereon, and, a multir sta e. alr compressor" as specified, claim 1, a turbine. wheel; made of Hiduminium alloy havin a: specific weight lower: than 4 and a Safe work;- ing. temperature limit of about, 400,? said wheel having: its, blades integral Withits spokes,- fqrming vanes, and; said vanes being exposed to the airtraversing said, primary compressien sta e- V NQRBERT GALL QT.

Number Number Name Date Griflith Dec.v 25, 1495 Youngash Mar. 5 1946 Heppner' Apr. 9, 1946 Halford June 11, 1946 Baumann Nov. 12, 1946 Pavlecka Jan. 21, 1947 Heppner Sept. 30, 1947 Bedding Aug. 10, 1948 =Shu1er May 3, 1949 Stalker Nov.,29, 1949 FOREIGN PATENTS Country Date Great Britain Jan. 29, 194?

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