US3544231A - Stator-blade assembly for turbomachines - Google Patents

Description

- Dw.1,1 970 F. ZERLAUTH 3,544,231

STATOR-BLADE ASSEMBLY FOR TURBOMACHINES 'ild Oct 1 1, 1968 I 3 Sheets-Sheet 1 I Inventor: Ferdinand Zerlcu'rh W BY W Dec. 1,1970- F. ZERLAUTH 3,544,231

STATOR-BLADE ASSEMBLY FOR TURBOMACH-INES Filed on 11. 1968 y 3 Sheets-Sheet 2 In vemor:

Ferdinand Zerlouth ATTORNEYS Dec. v1, 1970 STATOR-BLADE ASSEMBLY FOR TURBOMACHI NES Filed Oct 11. 1968 F. ZERLAUTH c-i*-it 5 Sneets-Sheet 25 Inventor:

Ferdinand Zerlourh W ATTORNEYS United States Patent 3,544,231 STATOR-BLADE ASSEMBLY FOR TURBOMACHINES Ferdinand Zerlauth, Winterthur, Switzerland, assignor to Sulzer Brothers Limited, Winterthur, Switzerland, a company of Switzerland Filed Oct. 11, 1968, Ser. No. 766,843 Claims priority, application Switzerland, Mar. 22, 1968, 4,329/ 68 Int. Cl. F01d 1/00, 25/12 US. Cl. 415-115 2 Claims ABSTRACT OF THE DISCLOSURE The present invention pertains to a stator-blade as sembly for turbomachines traversed by the working fluid approximately parallel to the axis of rotation of the machine. The term turbomachine is intended to denote a turbine-type machine Whether for development of mechanical energy at a rotating shaft from a fluid flowing through the machine as in a turbine, or for the delivery of energy from a rotating shaft to the fluid, as in a pump or compressor.

In accordance with the invention the stator blades are provided with coolant channels approximately parallel to the axes of those blades, and the blades are divided into groups or blading elements in each of which the blades are fastened together at the radially outer end thereof to a root or base which serves to hold the blading element in the stator blade carrier. Each blading element thus makes up a segment of a stator blade ring. At their radially inner end the blades of each blading element are joined to a hollow head member with the coolant channels in the blades opening into the hollow space of that head member. The head members of the blading elements or segments making up the stator blade ring or assembly of one stage of the machine form together a ring fitting between the roots or feet of the rotor blades of adjacent stages.

Advantageously all of the blading segments of a single stator blade ring are made up in the same way. In particular cases however it may be desirable to make the individual segments of a ring of different dimensions or with a different number of blades thereon.

The stator blade carrier may be provided either by the housing of the machine itself, or by means of a separate element provided within that housing. The blade segments may be made on a pattern, so that they can be fitted without play into the support therefor. In addition the blade segments, fastened as they are at their roots on a. larger circumference than the outer circumference of the individual blades, are better supported especially against axial stresses.

Cooling of the stator blades, as in application of the invention to high temperature turbines, can be readily effected by causing a coolant to flow through the feet of the blade segements, through the channels in the blades and into the hollow space of the blade segment head members. Alternatively, a heating medium can be caused to flow through the blades.

According to an advantageous further feature of the 3,544,231 Patented Dec. 1, 1970 invention the root portion or foot of each blade segment can likewise be made hollow and provided with at least one opening. Through this opening a heating or cooling fluid can be uniformly distributed to the blades. The foot of each blade segment may advantageously take the form of a fastening or support element, made of suitably shaped sheet metal welded to the blades, together with a profile member welded to that support element, fitting in a groove of the stator-blade carrier and enclosing with that support element a hollow space or cavity. The profile member may have radial as well as axial l0- cating surfaces by means of which centering of the guide blade array can be effected in the blade carrier or turbine housing.

In accordance with the invention, the hollow space in the head member can be closed at the radially inner end of the head member by means of a member having a shape matching with and complementary to a rotor member disposed between the rotor blades of adjacent stages. Further, to close that hollow space there may be employed sheet metal walls on three sides of a rectangular cross-section of that space with a profile member at the radially inner end of the head member on the fourth side. A Wear member may be provided at the radially innermost point of the blade segment. With the help of such a Wear member, and by proper control of the flow of coolant, the heating up of the stator blading can be so controlled on start-up and operation of the machine as to hold the rotor t0 stator-blade assembly clearance as small as possible. If however, for example on start-up, there should be contact between the rotor and the head members of a stator-blade array, damage will be avoided. Rather, the contacting surfaces will so shape each other that upon steady-state operation a small clearance will be preserved. By cooling of the blade segments, further expansion of the blades due to the heat generated by such frictional contact will be avoided.

The bearing surface of each head member is advantageously provided on a replaceable support. At least one boundary of the hollow space in each head member, and notably the sheet metal wall toward the high pressure end of the machine, can be provided with an opening directed toward the root of an adjacent rotor-blade set. The hollow space of each head member can also be subdivided by one or more partitions in order to promote uniform flow of temperature-control fluid. At least one opening di rected toward the foot of an adjacent set of rotor blades can be provided to at least one of these compartments defined by the transverse partitions.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 2 is a view again in axial direction showing at anenlarged scale a plan view of one segment of the statorblade array of FIG. 1; and

FIG. 3 is a section through the segment of FIG. 2 taken in a plane containing the axis of rotation of the machine.

In FIG. 1, the annular stator-housing is indicated at 4. It includes for at least some stages of the machine a groove 17 into which the segments 3 of the stator-blade ring or array of that stage are received. To this end, the stator-housing is split along a horizontal plane, i.e., a plane containing the rotor axis. On assembly of the stator, with the stator-housing opened along this split, the blade segments of each stage can be inserted and fastened in the lateral grooves 33 and 34, extending axially of the machine from the groove 17, as illustrated in FIG. 3.

applied, so that upon exposure of the blades to hot gases, in operation of the machine their exterior surface will so far as possible exhibit everywhere the same temperature.

At the root end away from the machine axis 7 (FIG. 1), the blades of each segment 3 are united by weld seams 6 to a sheet metal member 30 (FIGS. 2 and 3). Together, with the profile member 18, to which it is welded at 16, the sheet metal member 30 forms the blade segment foot 5. The profile member 18 fits, as shown, into the side grooves 33 and 34 of the groove 17. The hollow space 14 defined within the foot 5 communicates with the hollow groove 17 through the opening in the member 18.

At the radially inner ends thereof, the blades of each segment are welded, as indicated at 8, to a head member 12 common to the blades of that'segment, so that the channels 2 of those blades open into the cavity 13 of this head member. The head member is provided 'with sheet metal walls 21, 22 and 23on three sides of its rectangular cross-section (in planes containing the machine axis). On the fourth side adjacent the rotor axis, space 13 is closed off by means of a profile member 24. A body 25 of suitable material, mounted on a support 26 fastened to the member 24, constitutes a wear element, this element being replaceable with its support or shoe 26' on withdrawal of the pins 32. :By proper adjustment of coolant flow, the radial expansion and contraction of the blades 1 can be controlled to maintain under steady-state running conditions of the machine an extremely narrow clearance 35 from the rotor, generally indicated at 38. Upon initial start-up there may indeed be contact with the rotor. By reason however of the wear which then ensues, a very narrow clearance 35 will be established for steady-state operating conditions.

The hollow space 13 of the head member 12 possessesbores 29 directed toward the feet 10 of the rotorblades of the adjacent stages. It can be seen that a suitable gaseous, vaporous or even liquid cooling mediumcan be caused to flow out of the hollow stator-blade retaining grooves 17, .through the openings 15, the cavities 14, the blade passages 2 and thence into the hollow space 13 and therefromto flow as free jets through the openings 29 against the rotor-blade roots. The head members 12 of the stator-blade segments 3 thus constitute together a ring 11, (FIG. 1) closely surrounding the rotor-surface 36, this ring serving to minimize to negligible levels circulation of the machine Working fluid through the flow passages 2 of the stator-blades.

As is shown in FIG. 2, the hollow space13 of each head member 12 is closed at one peripheral end by means of a plug 19 which protrudes and extends into a matching cavity of a complementary plug 20 in the head member 12 of the adjacent stator-blade segment. The result .is to hold the segments rigidly in the plane of the statorblade array and also to seal oflf from each other the cavities 13 of the various blade segments making up the array. By this isolation of the hollow chambers 13, there is achieved a homogenization in the flow of coolant through the blades of the various-segments The cavity 13 in the head of each of thestator-blade 4 individual blades can likewise be evened out. The cross section of the exit apertures 29in theheadportion 12, much smaller than that of the openings 15 in the root portions 5, has as a consequence that the same quantity of heating or cooling medium will flow through each blade, but at increased pressure. The exit apertures 29 should have such a cross section as to permit the flow of a quantity of coolant suitable to the temperature 'at rIhe stage in question and also to the material employed for the blades thereof. After exit out through the openings 29, the cooling air flows for the most part in a surface layer over the walls 21 and 22 and thereby reduces contact between the head members 12 and the hot working gases flowing between the blades. Another portion of the cooling air passes through the clearance 35 and thereby closes that clearance to the hot working gases, thus preventing contact of those gases with the wear members 25, the shoes 26 and the profile members 24. The result is that these parts are protected from too high temperatures and too fast a heating up on start-up of the machine.

More than four blades, or on the contrary a smaller number than four, can be provided in the individual segments. Choice of the number of blades for this purpose is determined by the temperature conditions obtaining on start-up from a cold start, on the number of segments into which the whole array of stator-blades is subdivided, on the material employed and on the cooling circumstances obtaining when the machine is started.

While the invention has been described herein in terms of a presently preferred embodiment, the invention is not limited thereto but rather comprehends all variations on and departures from that embodiment properly falling within the spirit and scope of the appended claims.

What is claimed is:

1. A stator-blade assembly for axial-flow turbomachines, said assembly comprising a plurality of arcuate blade segments each including a plurality of blades having a radially extending channel therein, a root member aflixed to the radially outer ends of said blades, and a hollow arcuate head member affixed to the radially inner ends of said blades with communication between said channels and the interior of said head member, said head members constituting a substantially closed ring, each of said head members possessing a substantially quadrilateral section in planes containing the axis of said ring and being bounded on the radially outer end and on the axial ends of said section by sheet metal walls and by a profile member on the radially inner end of said section, each of said head members including at least one partition dividing the hollow interior thereof into plural compartments between adjacent blades thereof.

2. A blade assembly according to claim 1 'wherein each of said partitions has an opening formed therein.

References Cited 1 UNITED STATES PATENTS 5/1913 Junggren 25378 2,354,587 6/ 1944 Franck 25378 2,625,367 1/1953 Rainbow et a1 25339.1 2,997,275 8/1961 Beau et al. 25378 3,018,085 1/1962 Welsh 25377 3,025,037 3/1962 Beckstrom 25378 2,937,805 5/1960 Warnken 25378 FOREIGN PATENTS 24,657 1912 Great Britain.

661,178 11/1951 Great Britain.

723,505 1 2/1955 Great Britain.

HENRY F. RADUAZO, Primary Examiner US. Cl. X.R. 415

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