US3084907A

US3084907A - Gas turbine scroll mount

Info

Publication number: US3084907A
Application number: US66281A
Authority: US
Inventors: James P Simon
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1960-10-31
Filing date: 1960-10-31
Publication date: 1963-04-09
Anticipated expiration: 1980-04-09
Also published as: BE609664A; GB921694A

Description

April 9, 1963 J. P. SIMON GAS TURBINE SCROLL MOUNT 3 Sheets-Sheet 1 Filed Oct. 31, 1960 April 9, 1963 J. P. SIMON GAS TURBINE SCROLL MOUNT 5 Sheets-Sheet 2 Filed Oct. 31, 1960 INVENTOR. $44155 I? 374704 April 9, 1963 Filed 061;. 31, 1960 J. P. SIMON 3,084,907

GAS TURBINE SCROLL MOUNT ,3 Sheets-Sheet 3 jwmrmacw Arr-reel)! y United States Patent M 3,084,969? GAS TUREINE SrJRULL MGIJN'I James P. Simon, fincinnati, @hio, assignor to General Electric (Zcrnpany, a corporation of New York Filed-Bet. 31, 196%, Ser. No. 66,281 3 Claims. '(El. 253-39) This invention-relates to a scroll for ducting propelling gases to'a gas turbine and, more particularly, to mounting means for a gas turbine scroll wherein means are provided for non-rigidly supporting the scroll to allow for expansion and contraction of the scroll in response to temperature variation of the propelling gases passing through the scroll.

While this invention may have application in any turbine of the type hereinafter described, one example of the use to whichsuch a'design may'be put is in vertical take-oif aircraft, wherein a lift fan driven by a tip turbine provides vertical thrust to the aircraft for ascent and descent. In this use, turbine buckets carried by the fan blade tips or otherwise supported about the fan periphery are supplied with hot propelling gases for driving the 'liftfan and thus producing the necessary thrust for lifting the aircraft, the gases being ducted to the turbine buckets from a gas generator, such as a standard jet engine combustor, by means of a scroll. In this arrangement, both the turbine and the scroll would be mounted to the samcsurrounding structure such as, in the example used, the airframe of the aircraft.

sponse to variations in the temperature of the flowing gases. In order to prevent stresses from occurring in the scroll structure which might contribute to a structural failure, it is necessary to provide mounting means for the scroll which will permit natural expansion-and-contraction of the scroll over a wide temperature range. Since completely unrestrained expansion or contraction of the scroll may result in the nozzles or outlets being drawn out of alignment with the turbine buckets with consequent deleterious effects upon the turbine operation, it is also necessary that the scroll mounting means guide the scroll expansion or contraction along directions which will assure substantially correct continuous alignment of the nozzles and the-buckets over a Wide temperature range.

It is therefore an object of this invention to'provide animproved inlet scroll for a gas turbine.

Another object of the invention is to provide an improved mounting means for a gas turbine inlet scroll wherein themounting means permits limited movement of the scroll-due to natural expansion and contraction over a wide 'range of temperatures along predetermined directions in order to maintain continuous alignment of the scroll outlet openings and the turbine buckets to which the propelling gases are directed.

Briefly stated, in accordance with the illustrated embodiments of the invention, mounting means are provided for supporting a gas turbine inlet scroll with respect to the turbine at three points. The scroll, which wraps -about at least a sector of theturbine periphery, has a a curved configuration which conforms to the turbine pc- 3,984,590? Patented Apr. 9, 1963 riphery so that gases ducted through the scroll are directed through outlet openings or nozzles spacedalong'the length of the scroll against the turbine buckets. An inletopening to the scroll through which hot propelling gases enter is preferably centered along the length of the scroll and is set radially outward from the turbine periphery so that it clears the outer edge of the rotating rotor. A first support, which in some embodiments may be centered upon the scroll inlet, rockingly connects-the scroll to the surrounding airframe structure. Except for a slight rocking or pivoting of the scroll relative to the airframe at the point where the first support is attached, the scroll is fixed with respect to the airframe at that point. The scroll is supported on each side of the first support by second supports which'allow movement of the scroll relative to the surrounding airframe'and to the first support along predetermined directions, the directions preferably being along axes connecting the first support to each of the second supports. Thus, expansion of the scroll under the influence of the temperature of the propelling gases is permitted to take place in the predetermined manner to minimize the possibility of misalignment-of the scroll outlet nozzles which are positioned along the arc of the scroll and the turbine buckets which are positioned in a coinciding arc beneath the nozzles. Thus, with the arrangement of this invention, the second supports located on each side of the first support permit the scroll togrow outwardly from the fixed pointofsupport along predeter mined lines of movement.

While the specification'conc'ludes with claims particularly pointing out and distinctly claiming the subject matter of the invention, it is believed that the invention will be better understood from the following description taken in connection with the accompanying drawings in which:

FIGURE 1 is a fragmentary plan view of a turbine rotor and a partial admission scroll in their assembled relation with respect to one another, the scrollbeing supported by a presently preferred embodiment of'the mounting means of this invention in which the fixed support coincides With-the center ofthe scroll inlet;

FIGURE 2 is a partial view taken along line 2-2 of FIGURE 1;

FIGURE 3 is a partial view taken along line-33 of FIG-'URE'Q;

FIGURE 4 is a partial view taken alongline 44 of FIGURE 1;

FIGURE 5 is an alternative embodiment of the mounting support illustrated in FIGURE 4;

FIGURE 6 is a schematic view of the invention as applied-to a full admission scroll; v

FIGURE 7 is a schematic View of two partial" admission scrolls in combination to provide for full admission to the turbine, each scroll beingsupported-byasupport arrangement of an alternate embodiment of the invention in which one'of the fixed supports is offset from the center of the scroll inlet;

FIGURE 8 is a schematic view of a scroll supported by the mounting means of the invention, in which the scroll inlet is located at-the end of the scroll; and

FIGURE 9"is a plan view, similar to FIGURE 1, illustrating the expansion movement of the scroll.

Referring first to FIGURE 1, a turbo-fan rotor, generally indicated at 1t), is shown having fan blades 11. Carried about the periphery of the rotorare a plurality of turbine vanes or buckets 12. An arcuate or annular gas duct inlet scroll, generally indicated at 13, conforms tothe curvature of a sector of the turbine rotor Iii. An

inlet 14 which is radially spaced from-the turbine periphery admits propellinggasegas shown by the arrows in FIGURES 2 and 3, from a suitable gas generating v.3 means, such as the combustor of a conventional jet engine. Inlet 14 is preferably located equidistantly of each end of the scroll 13. The rotor propelling gases admitted through inlet 14 are ducted throughout the scroll 13 and are discharged through outlets or nozzles 12a arranged about the arcuate or curvilinear bifurcated duct portions or branches 15. This portion 1 5 overlies the turbine buckets 12., so that the outlets or nozzles discharge the propelling gases directly onto the buckets about the sector of the rotor covered by the scroll.

Centered with respect to the inlet 14 are the parts needed to support the scroll. There is a first support 16 rockingly mounting one point of the scroll to the airframe or other surrounding structure 17 by means of the other part shown. As seen in FIGURES 2 and 3, the support 16 is fixed to the scroll 13 in a crease portion 18 which divides the total flow of inlet air and directs a portion of the air into each of the branches 15. Except for a possible slight rocking movement of the scroll 13 at the first support point, the first support 16 fixes the position of the scroll relative to the airframe or other surrounding structure 17.

On each side of the first or fixed support 16, there is provided a respective second support 19, mounting the scroll at two points to the airframe or other surrounding structure 17, so that together with the fixed support 16, support of the scroll at three points is provided. Each of the second supports 19 preferably, but not necessarily as shown in FIGURES 6 and 8, located at the ends or extremities of the arcuate scroll are of a non-rigid or movable type to provide limited movement of the scroll along a single axis. Each of the second or movable supports 19 may be of a sliding type of any suitable form but, as illustrated in FIGURE 4, may take the form of a crosshead arrangement having a fixed bar 26 rigidly mounted to the airframe or other surrounding structure 17, and a link or bearing loop 21 adapted for sliding movement along the bar 20. The supports 19 are preferably oriented so that the movement of the slidable loops 21 and the consequent movement of scroll branches 15 will take place along axes drawn between each slidable support 19 and the fixed support 16 as shown in FIGURE 1.

As an alternative to the slidable support of FIGURE 4, the nonrigid or movable support 19 may take the form illustrated in FIGURE 5, wherein a suitable link 23 pivotally connects the scroll 13 to the airframe or other surrounding structure 17 at

pivot points

24 and 25, respectively.

It will be understood that the invention can take many forms in addition to the preferred embodiment shown in FIGURE 1. As shown in FIGURE 6, the mounting means of the invention can be used to provide a three point support for a full admission scroll as well as for the partial admission scroll shown in FIGURE 1. The full admission scroll 26 substantially entirely encircles the turbine rotor so as to provide gas admission to the turbine buckets around the entire turbine periphery. A first or fixed support 27 preferably centered upon the inlet 28 rockingly supports the scroll 26 relative to the airframe or other surrounding structure. Second or movable supports 29 are positioned on each side of the fixed .support 27 and are oriented so that movement of the scroll 26 takes place along axes intersecting the fixed support 27 and each of the movable supports 29. Likewise, the movable supports 29 need not be located at the ends of the scroll branches as shown in FIGURE 1, but may be located at convenient points along the length of the scroll branches 30 as shown in FIGURE 6.

Referring now to FIGURE 7, two partial admission scrolls similar to the one shown in FIGURE 1 can be used in combination in order to provide for full admission to a gas turbine. Each of the partial scrolls 31 is supported at three points by a first or fixed support 32 and by second or movable supports 33 spaced on each side of the fixed support. Although the fixed support may preferably be centered upon the inlet to the scroll as shown in FIG- URE 1, the fixed support 32 is shown in FIGURE 7 in an alternative position in which it is not centered over the inlet 34, but is spaced a substantial distance from the inlet along one of the scroll branches.

FIGURE 8 shows an alternative scroll embodiment in which an inlet 35 is located at one end of the scroll 36 rather than in the center of the scroll. The scroll 36 is supported at three points by a fixed support 37 and two movable supports 38 spaced on each side of the fixed support. It will be understood that the fixed support 37 may be centered on the inlet 35 as shown in FIGURE 8 or may be alternately displaced from the center along the length of the scroll as described for FIGURE 7.

Referring now to FIGURE 9, it will be understood that as propelling gases at elevated temperature are admitted to the scroll 13 via inlet 14 and are ducted through the scroll to the outlet nozzles 12a during operation of the engine, the elevated temperatures to which the scroll is subjected cause it to expand. Being only rockingly mounted to the surrounding structure at the fixed support 16, the scroll can only grow from the dotted line position radially outward to the solid line position from that fixed support as a center. The movable supports 19 permit this natural growth, but control the direction of growth along predetermined axes which, while straight or linear as 22, maintain the scroll substantially in alignment with the periphery of the rotor 10 and particularly with the turbine buckets 12. As an example, two different lines X and Y are shown. A given point 0, as shown on each of the lines X and Y at the cold dotted position of thescroll, moves in an outward direction along the X and Y lines to the point it, which is the hot expanded solid position of the scroll, showing how the parts are maintained in substantial alignment. Similarly, contraction of the scroll, as from the solid outline hot position of FIGURE 9 to the dotted outline cold position, taking place as the flow of propelling gases is decreased is controlled by the support arrangement so that alignment of the nozzles 12a with the buckets 12 is maintained. Thus, the scroll is supported for limited movement in the predetermined directions which directions are along the axes intersecting the fixed and movable supports.

In view of the foregoing, it will be apparent to those skilled in the art that the instant invention provides a means for supporting a gas turbine scroll whereby dimensional change in the scroll due to variation in temperature leaves undisturbed the desired alignment between the outlet nozzles carried by the scroll through which the gases pass from the scroll and the buckets of the turbine rotor against which the propelling gases are directed, thereby avoiding efiiciency loss or other deleterious effects upon turbine performance.

While the foregoing description has illustrated the invention as using the cross-head and pivoted link arrangements as the movable support for the scroll, it will be understood that the invention contemplates any such combination of elements wherein the scroll is supported at three points, one of which fixes the position of one point of the scroll relative to the surrounding structure while the other two movably support the scroll for limited movement in predetermined directions. Thus, for example, the concept of the invention could be adapted to an inlet scroll in which the inlet aperture is not centered with respect to the scroll ends as shown in FIGURE 8, or in which the axes of movement of the movable supports does not intersect the fixed support, or in which other forms of movable supports than the ones illustrated could be used. It is apparent that still other changes and modifications may be made in the construction and arrangement of the various parts without departing from the scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. For a gas turbine comprising a rotor having a plurality of fluid responsive elements on the circumference thereof and a surrounding structure,

an inlet scroll comprising a gas duct,

inlet opening means in said duct,

outlet nozzles along the length of said duct individually aligned with said elements,

and a three point support system including a first support substantially fixedly supporting said duct at One point and second and third supports each spaced along the length of said duct from said first support and supporting said duct for limited movement,

said first support comprising first and sec-ond parts, said first part being fixed to said duct and movably connected to said second part, said second part being secured to said surrounding structure, whereby slight rocking motion of said first part relative to said second part is permitted about a first axis,

said second support including means for confining said limited movement to a path along a second axis intersecting said first and second supports,

and said third support including means for confining said limited movement to a path along a third axis intersecting said first and third supports,

whereby thermal expansion of said duct caused by hot fluid flowing therethrough is directed primarily along said second and third axes to maintain the alignment of said nozzles with said elements.

2. For a gas turbine comprising a rotor having a plurality of fluid responsive elements on the circumference thereof and a surrounding structure,

an inlet scroll comprising a bifurcated duct having two arcuate branches,

inlet opening means in said duct,

outlet nozzles along the length of said branches individually aligned with said elements, and a three point support system including a first support substantially fixedly supporting said duct at one point and second and third supports each adjacent the end of one of said branches for supporting said duct for limited movement of the branches,

said first support comprising first and second parts, said first part being fixed to said duct and movably connected to said second part, said second part being secured to said surrounding structure whereby slight rocking motion of said first part relative to said second part is permitted about a first axis,

and said third support including means for confining said limited movement to a line along a third axis intersecting said first and third supports,

whereby thermal expansion of said branches caused by hot fluid flowing therethrough is directed primarily along said second and third axes to maintain the alignment of said nozzles with said elements. 3. For a gas turbine comprising a rotor having a plurality of fluid responsive elements on the circumference thereof and a surrounding structure,

an inlet scroll comprising a duct,

inlet opening means radially spaced from the periphery of the turbine,

two arcuate branches communicating with and extendfrom said inlet opening means around the periphery of said turbine and conforming generally therewith,

outlet nozzles along the length of said branches individually aligned with said elements,

and a three point support system including a first support fixedly supporting said duct at a point substantially centered upon said inlet opening means and second and third supports each adjacent the end of one of said branches for supporting said duct for limited movement of said branches,

said first support comprising first and second parts, said first part being fixed to said duct and movably connected to said second part, said second part being secured to said surrounding structure whereby slight rocking motion of said first part relative to said second part is permitted about a first axis, said second support including means for confining said movement to a path along a second axis intersecting said first and second supports,

and said third support including means for confining said movement to a path along a third axis intersecting said first and third supports,

References Cited in the file of this patent UNITED STATES PATENTS 921,832 Hersey May 18, 1909 1,050,136 Hodkinson Jan. 14, 1913 1,325,135 Baumann Dec. 16, 1919 1,373,289 Baumann Mar. 29, 1921 1,379,258 Guy May 24, 1921 1,846,550 Gottwald Feb. 23, 1932 2,119,376 Allee May 31, 1938 2,190,170 Campbell Feb. 13, 1940 2,564,042 Walker Aug. 14, 1951 2,615,300 Lombard Oct. 28, 1952 2,631,815 Holtzwarth May 17, 1953 2,800,297 Ergenc July 23, 957 3,004,388 Foulon Oct. 17, 1961 FOREIGN PATENTS 1,200,183 France Dec. 18, 1959

Claims

1. FOR A GAS TURBINE COMPRISING A ROTOR HAVING A PLURALITY OF FLUID RESPONSIVE ELEMENTS ON THE CIRCUMFERENCE THEREOF AND A SURROUNDING STRUCTURE, AN INLET SCROLL COMPRISING A GAS DUCT, INLET OPENING MEANS IN SAID DUCT, OUTLET NOZZLES ALONG THE LENGTH OF SAID DUCT INDIVIDUALLY ALIGNED WITH SAID ELEMENTS, AND A THREE POINT SUPPORT SYSTEM INCLUDING A FIRST SUPPORT SUBSTANTIALLY FIXEDLY SUPPORTING SAID DUCT AT ONE POINT AND SECOND AND THIRD SUPPORTS EACH SPACED ALONG THE LENGTH OF SAID DUCT FROM SAID FIRST SUPPORT AND SUPPORTING SAID DUCT FOR LIMITED MOVEMENT, SAID FIRST SUPPORT COMPRISING FIRST AND SECOND PARTS, SAID FIRST PART BEING FIXED TO SAID DUCT AND MOVABLY CONNECTED TO SAID SECOND PART, SAID SECOND PART BEING SECURED TO SAID SURROUNDING STRUCTURE, WHEREBY SLIGHT ROCKING MOTION OF SAID FIRST PART RELATIVE TO SAID SECOND PART IS PERMITTED ABOUT A FIRST AXIS, SAID SECOND SUPPORT INCLUDING MEANS FOR CONFINING SAID LIMITED MOVEMENT TO A PATH ALONG A SECOND AXIS INTERSECTING SAID FIRST AND SECOND SUPPORTS, AND SAID THIRD SUPPORT INCLUDING MEANS FOR CONFINING SAID LIMITED MOVEMENT TO A PATH ALONG A THIRD AXIS INTERSECTING SAID FIRST AND THIRD SUPPORTS, WHEREBY THERMAL EXPANSION OF SAID DUCT CAUSED BY HOT FLUID FLOWING THERETHROUGH IS DIRECTED PRIMARILY ALONG SAID SECOND AND THIRD AXES TO MAINTAIN THE ALIGNMENT OF SAID NOZZLES WITH SAID ELEMENTS.