US 2418801 A
Description (OCR text may contain errors)
K. BAUMANN IETERNAL CQHBUSTIOKi TURBINE lLANT 4 Sheets-Sheet 1 Filed Jim. 15, 1944,
Apfifl ,8; -3943? I a K @AUMANN I 3 INTERNAL COMBUSTION TURBINE PLANT Filed Jan. 13, 1944 a Shams-Sheet 2 atente pr.
WTERN-AL-COMBUSTION TURBINE PLANT Britain application January 13,1944, Serial No. 518,175
-, In Great Britain March 25, 1942 This invention relates to an internal combustion turbine plant, hereinafter called gas turbine plant, wherein the turbine drives a mu-lti-stage axial fiow air compressor, either directly or through gearing, so that the speed of the compressor is always the same as or is in direct relation to that of the turbine; said compressor, which comprises low and high pressure parts each having a plurality of blading stages, delivers to a combustion chamber, from which the products of combustion are fed to the turbine. To obtain the requisite efilciency of such plant both the turbine and the compressor, with respect more particulariy to the blading thereof, are designed to run at a predetermined speed so that a diflqculty arises when the turbine and compressor run at speeds lower than the optimum speed for which they are designed. An axial flow air compressor operates satisfactorily at a predetermined speed over a very limited range of air quantity. At quantities higher than the normal the delivery pressure drops rapidly, whilst at air quantities somewhat lower than the normal the compressor becomes unstable, due to stalling, resulting in a 14 Claims. (01. 230-114) is to blow off some of the air from an intermediate point of the compressor, conveniently at a point 'between'thehigh-pressure end of the low pressure section of the compressor and the low pressure end of the high pressure section of the compressor, whereby the lowest pressure compressor blades may deal 'with a larger quantity of air than the highest pressure blades of the compressor and the turbine. This method, moreover, can be readily carried out as previously proposed in relation to the stationary casing of the compressor by the provision therein of valved portswhich may be openedto various extents, either by hand or automatically, when the speed drops below a predetermined value. However,
when the air compressor is of the contrarotational type, some examples of which W1 se form the subject matter inte'r'alia of U. 8. applications Serial Nos. 518,168 and 518,170, filed of even date herewith; this method cannot well be applied to the outer casing, since it is rotating. The
present invention ismor'e particularly, but not exclusively, applicable to contrarotational air considerable drop in the delivery pressure and in emciency. Furthermore, the turbine is' designed so that the quantity of air, together with products of combustion which it can deal with as received from the compressor via the combustion chamber, is within the range of emcient operation of the compressor at substantially the normal speed. -When, however, the speed is reduced more and more below normal the "swablowlng capacity of the turbine is reduced at'a greater rate than is the natural output of the compressor, with the result. that below a given due to the stalling of the compressor. This means are provided on the inner rotating casing speed theplant ceases to function satisfactorily,
stalling of the compressor at the lower speeds is initiated in the blading at the inlet end of the compressor, since at such lower speeds the compression ratio, and consequently also the ratio ofair volumes at the inlet and outlet ends is reduced. The area of the low pressure blading is too great for the amount of air passing through the blading at the high pressure end of the compressor and through the turbine. These difllculties per se could be alleviated by making provision for the opening of additional gas nozzles in the turbine, but in practice this provision is difilcult to carry out: or provision may be made for blowing off some air at the delivery end of the compressor, but this provision is conducive to inefllciency of operation. A more satisfactory method of dealing with the aforesaid difiiculty compressors. Accordingto the invention, with the above considerations in, view, automatically operating of the compressorwhereby air may be blown or taken oil from an intermediate stage thereof,
ilti either simply to atmosphere or preferably through a. duct or ducts leading-to the air inlet end of *the compressor. These means may be provided either alone, or in addition to means provided on the outer casing for blowing oif a1; from an intermediate stage of the compressor-when the outer casing and associated rows of blades constitutea fixed structure, audit will be appreciated that the air drawn ofl, according to the present invention will be in greater quantity than that which may be withdrawn in per se otherwise known manner solely for the removal of "boundary layers."
In carrying out the invention according to the preferred arrangement there is in the rotating inner blade-carrying drum or cylinder of the compressor at the'intermediate stage thereof a port or plurality of ports through which the excess air-obtaining at the intermediate stage at the lower speeds can pass to atmosphere, or through the aforesaid duct, and in either case through one or more valved ports the opening ofwhich can be controlled by one or more valve members in accordance with the speed of rotation of the compressor; The one or more valve the port or ports is or are normally fully open at 'the low speeds and adapted to be automatically gradually closed as the speed increases, and to be fully closed at a speed at which satisfactory operation of the plant can take place. To this end one or more valve members may be springbiased to the fully open position and closed by means of devices of the centrifugal governing type which may assume the forms hereinafter described.
There may be a single valve member co-operating with a plurality of ports or there may be a plurality of valve members each associated with a respective port, whilst the valved ports are preferably in a "diaphragm" member disposed within the rotor so as to separate the ports in the latter from the atmosphere or from the aforesaid duct leading to the air inlet end of the compressor. When there are several valve members they may operate synchronously gradually to vary the opening of the ports similarly with the speed variation o'r they may be arranged to open the ports consecutively, in which case the valve members may operate with snap action.
The valve members may operate in sliding contact with the diaphragm member, but preferably they operate by moving to-and-away therefrom. In the formeri-ifas'ethe diaphragm member may be a radial annulus with axial ports, and in the latter case it may be a radially ported cylindrical sleeve mountedcoaxially within the compressor rotor; in either case the ported diaphragm is preferably" rigidly connected to or is even integral with the compressor rotor.
In carrying out the invention a ported diaphragm is provided within the rotor, and the diaphragm has associated with it a valve member or valve members by which the extent of opening of the diaphragm ports is varied under centrifugal action.
In one arrangement the diaphragm is a radial or conical or coaxially cylindrical member, and thevalve may be a similar washer-shaped or conical member, also having ports, and the relative movements between the ported diaphragm and the valve may be controlled by spring-biased centrifugal members, or the valve or valves may be constituted by one or more springs or by spring-biased blades, all as will hereinafter appear.
In the accompanying drawings:
Fig. 1 is a sectional elevation in a conventional form of the upper half of the high pressure end or section of an air compressor having one form of the invention associated with it,
Fig. 2 is an end view, partly in section, of the arrangement shown in Fig. 1, 4
Fig. 3 is a view similar to Fig. 1 showing a modified arrangement in accordance with the invention,
Fig. 4 is a section of thecylindrical diaphragm member, taken on the line IVIV of Fig. 3,
Fig. 5 is a sectional elevation of another modification of a valved diaphragm according to the invention,
Fig. 6 is a sectional end view of the arrangement shown in Fig. 5.
Fig. 7 is a sectional elevation. and Fig. 8 an end view of a still further modification in accordance with the invention.
Referring first to Figs. 1 and 2, at l is shown the outer casing of the low pressure stage or section of a compressor carrying the alternate stages of blading as shown and 2 is the rotor carrying the intercalated blading stages as shown. It is to be understood that the casing member 5 may be arranged to rotate in the opposite direction to the rotor 2 in a contra-rotational compressor.
At 4 and 5 are shown stationary wall members constituting the annular air inlet to the illustrated compressor or compressor section. Integral with, or attached to, the annular member 5 is a diaphragm 5a carrying or integral with a bearing housing or support member 5b .(shown purel diagrammatically) carrying bearings 6 for a hollow sleeve shaft 1 which flares at la into a cylindrical portion lb attached to or integral with which is a conical portion 70 having a peripheral flange 7d which is bolted to a flange 2a integral with or secured to the rotor cylinder 2 and provided with a plurality of circularly distributed ports 8. The ported flange 2a constitutes the diaphragm hereinbefore referred to and bolted to it is the internal flange of a conical member 9 integral with or secured to the rotor, a part of which is indicated at H), of the high pressure compressor. The right-hand end of the rotor cylinder l0 and the left-hand end of the rotor cylinder 2 are shaped and spaced apart as shown to leave the sloping annular duct or a plurality of holes it through which can flow the air to be bypassed.
The sleeve portion lb, lb has housed within it on ball bearings 12 and I3 an inner sleeve or cylinder 14 in the space between which and the sleeve portion lb, lb is a helical spring [5, preferably formed of square section wire, having its right-hand end anchored at 'le to the sleeve lb, whilst the other end of the spring is anchored at Ma to the sleeve H. To the left-hand end Nb of the sleeve I4 is secured by one or more keys l6 and nut I! the hub of a toothed wheel I8.
Meshing with the toothed wheel it! are two or more unbalanced centrifugal members 19, symmetrically distributed around the rotor flange 2a so that the dynamic balance of the rotor as a whole is not disturbed. Each member I9 is pivoted on a pin 20 with a bearing sleeve 2! the pins 20 being secured by nuts as shown to the dia phragm flange 2a and the members l9 being accommodated. in the main in a recess 2b in the flange 2a and covered by the flange of the member 9.
Each centrifugal member H! has two toothed rim portions 19a and it"), the teeth of the latter engaging with the wheel 18. The member l9, as clearly shown in Fig. 2 has a cut-awa portion on one side and the solid or weighted portion .I Be on the opposite side of the axis. It is further provided with the projection I'Sd which can oscillate between abutments 22 provided either by cutting away a portion of the diaphragm flange 2a or by forming a recess in the flange of the member 9. I
The ported valve member is shown at 23 and it is of washer shape, having round the whole (or, as shown, portions) of its periphery teeth 230: which are in permanent mesh with the teeth 19a of the centrifugal member 19. The valve member 23 is at its toothed hub portion 23b of greater thickness, bearing in the periphery of the recess 2b of the diaphragm flange 2a.
As hereinbefore indicated the ports in the valve member 23 are caused by means of the spring 15 to register with the ports 8 in the diaphragm 2a so that when the rotational speed of the plant is less than the predetermined minimum, air will be bypassed through the annular duct H, through the ports 8 into an annular space 24 provided by the inner surface of the right-hand part of the rotor 2 and by a flaring I wall 25, the left-hand end of which has a flange 25a between the diaphragm flange 2a and the flange Id of the shaft 1. The right-hand end of the annular wall 25 is curved as shown at 25b and provided with guide blading 256, so that the bypassed air is constrained to flow back into the inlet of the low pressure section of the compressor through the gap 23 provided between the stationary wall member 5 and the right-hand end of the compressor rotor. cylinder 2. The
right-hand end 25b of the wall member 25 is shaped so that the bypassed air may provide an injector eiiect upon the intaken air whereby to prevent or minimise the stalling efiect, namely by appropriately directing bypassed air into the main air flow in the low pressure stage or section of the compressor. Furthermore, the guide blades 250 may be arranged to impart to the bypassed air a relatively circumferential com.- ponent of motion suited to the angle of the blading of the first row of rotating compressor blades. In addition, or alternatively, the guide blading 250 or boundary members may direct the ilow of the bypassed air slightly outwardly at such angle that there will be created an annular zone or dead space, as indicated by the dotted line 21, at the radially inner ends of the compressor blades, which are toosome extent inactive with respect to the main air fiow, whereby to give in effect a shortening of the blade heights so as to reduce the eiiective annular blade area presented to the main air intake and to the passage of this main air through at least the earlier rows or stages of blading.
Referring next to Figs. 3 and 4 of the drawings, it will be seenthat, apart from minor differences, the arrangement therein illustrated differs in the main from that illustrated in Figs. 1 and 2 in that the ported diaphragm 2a of these earlier figures, instead of being a radial flange, is a cylindrical member 28, having arcuate ports 28a, of which about any one radial plane there are four in number as clearly shown in Fig. 4,
whilst there are four sets of such ports distributed axially along the cylinder 28 as clearly shown in Figure 3.
The cylinder 28 is constructed separately from the rotor 2', and is connected to the latter by means of screws 29 passing through the flange 28b to a conical annular member 30, the righthand end of which is secured by screws 3! to the conical disc 32, which, at its flanged outer periphery, is screwed to an annular lug 20 on the rotor 2.
The conical disc 32 forms part of the'fiaring end 32a of the shaft 3% of the rotor 2 and is provided with ports 320 through which air which is permitted to flow through the ports 28a of the cylindrical diaphragm 28 can pass as constrained by the wall member 25d, the outer periphery of which extends into the gap 23inctween the stationary member 5 and the righthand end of the'rotor 2 in a manner which may be similar to that shown in and described with reference to Fig. l. The inner periphery of the wall member 25d is secured to the flaring por tion 32a of the rotor shaft 321).
In Fig. 3 the rotor 2 is shown as formed at the left-hand end of the low pressure part or section with an annular slit or a plurality of holes 2d through which at the gap H, the air to be bypassed can flow, thence leaving through the holes 26 into the space within the compressor rotor 2' wherein it is confined and is caused to flow in the direction indicated generally by the long arrow, by a transverse wall member 25c the outer periphery of which may be conical and is secured to the inner surface of the rotor 2'.
At 33 is shown another ported cylinder fixed within the diaphragm cylinder 28 by a flange 33a and the screws 29. The ports 33b of the inner cylinder 33 are relatively radially staggered to the ports 28a in the diaphragm cylinder 28.
The diaphragm cylinder 28 is formed interiorly with a plurality of radial lugs 280 which serve as guides for the valve members 34, of which there are four in number as clearly shown in Fig.
3. Each valve member 34 is in the form of a 0- spring and co-operates with one peripheral row of the ports 28a in the diaphragm member 28. Each spring valve 34 preferably subtends the most part of 360, its adjacent ends, when in its contracted condition, meeting the opposite sides of an abutment 35 riveted to the inner ported cylinder 33 (or may be to the diaphragm cylinder 28), the springs, when in contracted condition, more or less closely embracing the inner cylinder 33, all as clearly shown in Figs. 3 and 4. The bypassed air from the holes 211 and 2e flows radially through the ports 33b in the inner cylinder 33, then taking axial component of direction to flow substantially radially out through the ports 28a in the diaphragm 28.
It will be understood that as the rotational speed of the plant increases the normally open ports 2811 will be more and more closed and finally completely closed at the predetermined speed by reason of the springs 34 expanding under centrifugal force.
In order .to preserve dynamic balance the spring valves 3%, if two or more in number, have the gaps therein evenly circularly distributed in the axial direction along the diaphragm cylinder 28.
In order that each spring 34 will, in its fully.
extended condition, conform to the inner surface of the diaphragm cylinder 28, the radial thickness of the spring 3% may vary, being thickest at the centre of its peripheral length, as will be well understood.
In the arrangement illustrated in Figs. 5 and 6 of the accompanying drawings, which arrangement is a modification of that illustrated in Figs. 3 and 4, the diaphragm cylinder 28 is shown as of shorter axial length and provided with one circular row of four ports 28a, each having cooperating with it a centrifugal (unbalanced) valve member comprising a substantially rigid arcuate blade 36 integral with a shaped hub por tion 36a, having a bearing sleeve 36b and carried on an axle 31, the end of which is engaged in a perforation in two washer-shaped members 38 and 39 which have axially extending spacer portions 38a and 39a and which are secured together by a plurality of bolts 40. The bolts 40 secure the members 38 and 39 to an internal flange 28d of the ported diaphragm member 28. The axles 31 are carried in lugs 3% extending radially from the members 38 and 39.
Also housed between the members 38 and 39 is an annular rotatable member 4| which has for each valve a radial bifurcation Ma engaging a pin t2 fixed to a radially inwardly extending portion 360 of the hub portion of each valve member 36, of which the blade portion constitutes the centrifugal mass, ,being thrown outward at the predetermined speed to lie flush against the inner surface of the diaphragm cylinder 28, thereby closing the ports 28a therein.
It will be appreciated that instead of the bifurcation Ma the relatively rotatable member M ment is such that balance is obtained during rotation. It will be appreciated that the springs "and inherently contract themselves inwards and expand under centrifugal action. Alternatively, however, springs may be used which normally tend .to expand outwards, in which case each spring, as shown inFigs. 7, 8 at 431?, b, has one of its ends in contact with a fixed abutment 45 and its other end against an abutment 4 l b on the relatively rotatable member c, which is shown as having teeth 4 Id, which, as described as an alternative with reference to Figs. 5 and 6, engage corresponding teeth on the portions 86c.
0f the hub portions 36a of the valve members 38 Otherwise the arrangement -is the same asthat illustrated in Figs. 5 and 6, whilst it will be appreciated that a separate spring may be provided for biasing each of the valves.
I claim: r
1. A gas turbine plant including a multi-stage axial flow compressor having an inner rotating casing, means associated with said inner casing through which air may be withdrawn from an intermediat stage of the compressor, and means operating automatically to eflect the opening of said last named means when said casing is rotating at a speed predeterminately less than the optimum speed of the compressor. r
2. A ga turbine plant including a multi-stage casing, means associated with said inner casing through which air may be withdrawn from an intermediate stage of the compressor, said last of said port when said casing is rotating at a speed predeterminately less than the optimum speed of the compressor.
.3. A gas turbine plant including a multi-stage through which air may be withdrawn from an intermediate stage of the compressor, said last named means including a member within said casing and having at least one normally open valve port, and valve means for gradually closing said port as the speed of said casing increases closing said port at a predetermined higher speed. 4. A plant according to claim 2 wherein said valve means is biased to open position.
5. A plant according .to claim 2 wherein said valve means is normally open below a predetervalve means is normally urged to open position by spring means.
axial flow compressor having an inner rotating casing, means associated with said inner casing above a predetermined minimum speed and fully axial flow compressor having an inner rotating named means including a number within said inner casing and having at least one valve port, and valve means operative to effect the opening mined speed of said casing andare provided with 8. A plant according to claim 2 wherein said Number 9. A plant according to claim 2 wherein said valve means'is normally urged to open position by spring means and unbalanced centrifugal means acts in-opposition to said spring means.
10. A plant according to claim 2 wherein said valve means is constituted bya spring.
11,. A gas turbine plant including a multi-stage axial; flow compressor having an inner rotating casing, means associated with said inner casing through which air may-be withdrawn from an intermediate stage oi'the compressor, means operating automatically to effect the opening of said last named means when said casing is rotating at a speed predeterminately less than the optimum speed of the compressor, and means for returning air withdrawn from said intermediate stage to the inlet end of the compressor.
12. A gas turbine plant including a multi-stage axial flow'compressor having an inner rotating casing, means associated with said inner casing through which air may be withdrawn from an intermediate stage of the compressor, means operating automatically to eflect the opening or said last named means when said casing is rotating at a speed predete'rminately less than the optimum speed of the compressor, and means for returning air withdrawn from said intermediate stage to the inlet end or the compressor, said last named means including means whereby the returned air will provide an injector action at the inlet end of the compressor.
13. A gas turbine plant including a multi-stage axial flow compressor having an inner rotating casing, means associated with said inner casing through which air maybe withdrawn from an .intermediate stage of the compressor, means opcrating automatically to efiect the opening of said last named means when said casingis rotating at a speed predeterminately less than the optimum speed of the compressor, and means-for returning air withdrawn from said intermediate stage to the inlet end of the compressor, said .last named means including guide blades for imparting a circumferential component of motion to the air returned to the inlet end of the compressor. 1
- 14. A gas turbine plant including a multi-stage axial flow compressor having an inner rotating casing,-m'eans associated with said inner casing through which air may be, withdrawn from an intermediate stage of the compressor, means operating automatically to effect the opening of said last named means when said casing is rotating at a speed predeterminately less than the optimum speed of the compressor, and means for returning air withdrawn from said intermediate stage to the inlet end of the compressor, said last named means including meansfor directing the air returned to the inlet end of the compressor .file of this patent:
I UNITED STATES PATENT Name Date 1,111,498 Rotter Sept. 22, 1914 2,234,733 Jendrassik Mar. 11, 1941 2,314,058 Stalker Mar. 16, 1943 2,344,835 Stalker Mar. 21, 1944