US2868500A

US2868500A - Cooling of blades in machines where blading is employed

Info

Publication number: US2868500A
Application number: US144229A
Authority: US
Inventors: Boulet George
Original assignee: Individual
Current assignee: Individual
Priority date: 1949-02-15
Filing date: 1950-02-15
Publication date: 1959-01-13
Anticipated expiration: 1976-01-13

Description

BouLET Jan. 13, 1959 cooLING 0E BLADES 1N MACHINES WHERE BLADING Is EMPLOYED Filed Feb. 15, 195o '2 Sheets-Sheet 1 M E WARN@ Jan. 13, 1959 G. BouLET 2,868,500y

COOLING oF BLADES V1N MACHINES WHEREk BLADING 1s EMPLOYD -Filed Feb.l 15, 195o 2 sheets-sheet 2 ice COOLING OF BLADES IN MACHINES WHERE BLADING IS EMPLOYED `Georges Boulet, Toulouse, France Application February 15, `1950, Serial No. 144,229 `Claims priority, application France February 15, 1949 3 Claims. (Cl. 253-39.1S)

` My inventionrelates` to machines provided with sets of blades,jwhether carried by 'a stationary or a moving part of the machine, in particular to turbines, compressors, and more particularly to machines having internally cooled hollow blades. t

An object of my invention is to provide cient cooling of the blades.

Another object is to provide for an eflicient and well ruled circulation of cooling fluid through the various blades. j

A further object in the case of multistage machines is to transfer `heat from a stage to another by means of an innerfluid circulation through the blades from the most heated stage to the less one. Once this object attained, a still further object is then to provide multistage machines adapted to operate nearly isothermically, and in particular a nearly isothelmidmultistage compressor.'

Still another object is to provide machines having at least one blade wheel` the blades of which are cooled by an inner circulation of cooling fluid, and therefor blade wheels or barrels carrying blades cooled as just said and which will be light, easy to machine and assemble, fluidtight and reliable in operation.

With these and other objects in view as will appear from the description given `hereinafter ofvarious embodiments of` my invention, the latter consists in the provision and combination of means, and arrangement of parts, as will appear from said description and be more fully pointed out in the claims.

In the annexed drawings:

Fig. 1 is a section, through the axis, of a three-stage .'turbine of `which the stationary and moving blades are cooled; j t

Figs. 2, 3 and 4 are respectively cross-sections carried out at various distances from the axis of rotation alongthe lines II--IL III-Ill,` and IV-IV of Fig 1; j Fig. 5 is a diagrammatic end-view of a cooling device for stationary blades;

Figs. 6 and 7 are respectively cross-sections along the lines VI-VI and VII-VII of Fig. 1;

Fig. 8 is an elevational diagrammatic View of a turbocompressor with` cooled blades; and

Fig. 9 is a View similar to Fig. 8 of a modied embodiment of cooling means for the blades of a turbocompressor.

In the embodiment illustrated in Fig. l and that refers l toa three-stage turbine, each of the stagesV is provided, inthe usual way, with a" plate 1 to the periphery of which are fastened the blades 2 that are hollow; each blade is fitted through its base with cross-section in the shape of a parallelogram (Fig. 2) over a teat of the same shape cut inthe periphery of the plate 1, the base of the blade itself being imbedded in the grooves formed between two adjacent teats. The space between `two adjacentlplates is "closed by a rippled wall 3, in the shape of a surface of revolution, fastened to these two plates;

as shown the distance of said wall to the axis of rotation of the turbine wheel decreases from the rst stage, the blades of which are the most heated by the fluid flowing through the machine, to the other stages the blades of which are less heated by said fluid. Outside this wall is an outer ring 4 with U-shaped crosssection with its opening directed towards the rotary aXis of the turbine and that is also fastened to these ad jacent plates 1. A closed chamber 5 is thus provided between two adjacent plates; the adjoining chambers are in communication with each other through holes 6 going right through the plates in their central portion. A chamber '7 is arranged likewise on the outer surface of the end plates andis demarcated by an outer surface fof the plate and rippled wall 8 coveringthis surface and fastened to the plate in question; this chamber 7 connects up also with the chambers 5 through holes 6 arranged in the central portion of the end plates. Radial tubes 9, l0 project into each blade 2 and are arranged respectively with one nearthe leading edge of the blade and the other near the trailing edge. These two tubes emerge in the neighborhood of the blade end the farthest away from the rotary aXis. They are fastened in the rim of the plate carrying the blade, a rim through which they go to emerge in the chambers 5 or 7. Furthermore, each plate 1 is provided in register with each blade with a radial passage 12 hollowed out in the body of the plate and that cuts one of the cross holes 6; it emerges on the other hand substantially in the centre of the fastening teat fitted on the base of the blade. t It will be understood, under these conditions, that if there is in the chambers 5 and 'l` and inside the hollowed blades a cooling fluid, the latter, as it is being heated through the passing of the propelling jet between-the blades, will become heated more inside the blades than in the chambers 5 and '7 and that, as` a consequence of the ensuing density variation, the denser fluid contained in the chambers 5 and 7 is centrifugalized through the tubes 9 and lll While the warmer and less dense yfluid is forced back by the previous one through the passages 12 and 6 and returns into the chambers 5 and 7. There is thus self-circulation inside the blades. It appears beneficial to make use of, as cooling uid, a material possessing a vapor# izing point that is less than the ordinary temperature of the propelling jet. There thus takes: place a vapor.

ization inside the blades while the chambers 5 and 7 enclose this material in the liquid or solid state. This material, for instance, may be formed, to advantage, by metallic salts as in standard practice.

On the other hand, since the different chambers 5 and 7 link up with each other, there' occurs between them a more or less well-marked equalizing of the temperature so that the heat removed in the first blading set may be used to reheat the last lot of blading or several of the other blading sets and that there is thus automatic regeneration of power. It is therefor clear that the uid within the chambers 5 and 7 ie at a temperature less than that of the most heated blades but greater than that of the blades of the less heated stage or last stage.

Fig. l shows besides theaddition to the previous device of means intended to cool the fluid that circulates in closed circuit in the blades. For this ptnpose, in the chambers 5 located between two adjoining plates 1, there are arranged heat exchangers 14 formed in this case by annular flat chests with rippled wall carried by a central hollow hub l5. Thisv hub is tted directly on the adjoining plates l. so as to form with them a continuous wall and the whole block of the plates and the hubs fitted on each other is held assembled toi gether through longitudinal stay-rods 16. The inside of the chest ill is in communication through radial holes i7 and i8 with the inside of the hollow hub i5. A partition l@ inside the hub splits up the inner space of the latter into two divisions with no communication with each other and this partition 19 is fastened to a central tube 2i) that is concentric with the rotary axis and fastenedv to the body of the plate l of the rst stage. The inside of this tube is in communication, through holes 2l, with the division 22 on the upllow side of the hub 16 while the other division 23 communicates freely round the tube 2li with the division 22 of the heat exchanger arranged in the adjacent chamber 5.

To the body of the plate of the last stage is fastened a tube 24 that is outside and concentric with the tube with which it demarcates an annular passage 25 in communication with the division 22 of the heat exchanger arranged between the penultimate and the last stage. gether, through the instrumentality of revolving joints 26, to a stationary outer collector 27 provided with a circular volute 2S, communicating With the annular passage 25 and provided with an outlet pipe 29, and

a central passage 3o. The pipe 29 and the central passage 3i? are connected through a pipe system, that is not shown, to means enabling a cooling fluid to be delivered through the central passage 3@ into the tube 20 from where the fluid goes through the holes Zit into the head division 22 of the tirst exchanger 14, circulates inside the latter, leaves from it through the holes i8 into the division 23 from where it makes its way into the second exchanger and leaves from the latter through the annular area 25 between the tubes Z0 and 24- and goes away, through the pipe 29 of the collector 27. Any suitable heat exchangermay be inserted in the outer pipe system.

The stationary blades of the turbine shown in Fig. l are Vcooled likewise. For this purpose, they are hollow and are provided with an extension that goes through the outer wall 36 of the annular jacket where the propelling jet circulates and these extensions are immersed in a common cooling casing 37 that surrounds this jacket of which the outer wall forms preferably one of the walls of this casing; pipes 3S and 39 carried by this casing enable it to be connected through pipe systems, that are not shown, to means enabling a cooling liuid to be circulated therein, preferably in the same direction as that of the outliow of the propelling jet as shown by the arrows in Fig. l. blades 3S are filled with metallic salts in a pasty form adapted to be vaporized at a temperature lower than that of the propelling jet.

A modication of the cooling of the stationary blades of a turbine is shown in Figs. 5 and 9. In this modification, there enter into each hollow blade two tubes di, 42 headed towards the axis of the blading and that emerge inside the blade at two points that are at different distance from the axis. These two tubes 41, 42 are connected respectively to two dilerent collectors 43, i4 of annular shape and that surround the blading. The collector i3 is connected to the tube emerging nearest to the rotary axis and is of lesser cross-section than the collector 44 into which converges the tube 4t2. The collectors 43 of the various bladings are connected up with a main pipe 45 while the collectors 4d are connected to a pipe 46. Means not shown drive back into the pipe 45 a cooling fluid, preferably of metallic salts in a liquid state, salts of sodium for example; this uid is delivered, through the passage 45, to the various collectors 43 and, through the latter, to the tubes 4l of the different blades of each set of blading, then it leaves from these blades through the tubes 42 and is gathered together in the various collectors 44 from `where it comes back through the general passage 46,

The

tubes

20 and 24 are connected to- These stationary d by means that ensure its circulation. There is therefore in this case forced circulation inside the vanes. This mannerof carrying out the cooling of the stationary blades may be pointed out especially in the case of thin blades.

The various means as described for cooling the stationary blades and the moving blades of a turbine refer equally well to compressors, especially to axial compressors as shown in Figs. 8 and 9. In this case, however, in order to get as near as possible to isothermic compression, there is a separate casing 37a for the cooling of stationary vanes per compressor stage and these different casings are connected up in parallel on the distributors 50, 5l for the inlet and outlet of a cooling fluid of which the` circulation is ensured by outer means connected to this distributor and that are not shown. Owing to this arrangement, the different compression stages may be kept substantially at the same temperature.

The same result may be secured in the case of cooling of the vanes through forced circulation and common feeding through a general passage as disclosed hereinabove for the turbine shown in Fig .9.

Instead of feeding the various bladings or the various collectors through a distributor common to all the stages, each stage may be fed also through a separate pipe system or else sets of several stages and use may be made for each stage or each set of stages of a different volatile liquid suitable to the working temperature.

My invention, of coursejis restricted in no way to the details of execution as shown or disclosed, which have been given only as an example. So it is that, without going outside the scope of the invention, the stationary vanes of a compressor or of a turbine may be cooled only or solely by the moving vanes.

In the caseof machines provided with a multistage blading two or more stages of hollow blades may also be serially connected in order that a circulation may be provided within the hollow blades from the more heated stage to a less heated one.

What I claim is:

l. In a bladed uid ow machine required to run at high temperature comprising a rotary wheel, blades carried by the latter, at least some of which are each internally provided with a cavity enclosing a cooling material of a nature such that it is within said cavity in a liuid state at the normal running temperature of the rotary wheel, and heat exchanging means carried by said wheel and in operative cooling relation with said cooling material to cool the latter, said heat exchanging means including a fluid tight chamber, and for each cooled blade at least two ducts both communicating at one of their ends with said chamber and at their other ends with the cavity of a blade, the emerging points of one of said ducts in the associated blade cavity and in said chamber being respectively further remote from the wheel axis than the corresponding emerging points of the other duct in said blade cavity and in said chamber.

2. In a machine as in claim l, wherein further said wheel blading comprises a plurality of cooled blade stages, said cooled blades of at least two dilferent stages hav ing their respective ducts emergingin one and the same huid tight chamber.

3. In a bladed fluid flow machine required to run at high temperature comprising a rotary wheel, blades carried by the latter, at least some of which are each internally provided with a cavity enclosing a cooling material of a nature such lthat it is within said cavity in a fluid state at the normal running temperature of the rotary wheel, and heat exchanging means carried by said wheel and in operative cooling relation with said cooling material to cool the latter, said heat exchanging meansv including a tluid tight chamber in communica@ tion with said blade cavities and containing said cooling material, said rotary wheel comprising a plurality of cooled blade stages, the cooled blades of at least two different stages having their respective cavities in communication with the same chamber.

References Cited in the file of this patent UNITED STATES PATENTS 1,601,402 Lorenzen Sept. 28, 1926 1,938,688 Brooke Dec. 12, 1933 1,960,810 Gordon May 29, 1934 6 Noack July 10, 1934 Darrius Mar. 7, 1939 Planiol et a1 Feb. 20, 1945 Halford June 11, 1946 Constant Aug. 28, 1951 FOREIGN PATENTS Great Britain May 24, 1949 France Mar. 29, 1945