US 3802797 A
A reversing gas turbine has two coaxial rows of oppositely curved rotor blade portions and two rows of separately adjustable stator blades controlling flow of a motive fluid alternatively to the forward or reversing rotor blades. A divider baffle is disposed between the outer and inner liners of the inlet passage to the adjustable stator blades. The divider baffle serves to guide the motive fluid flow to the row of adjustable stator blades being utilized during a selected mode of operation of the turbine. The present invention provides a structure for supporting a divider baffle between the outer and inner liners of the turbine inlet.
Description (OCR text may contain errors)
United States Patent 1191 SUPPORT Inventors: Miles F. Bintz; Raymond L.
Dehmer, both of Schenectady, NY.
Assignee: General Electric Company,
Filed: Jan. 15, 1973 Appl. No.: 323,818'
References Cited UNITED STATES PATENTS 10/1954 McLeod 415/79 11/1956 Thorp 11/1966 .Scheper, Jr. 415/153 Z1 19 5 1:\\ any m/ 1 Iflfl 1 t \\\t-% it f Bintz et a1. Apr. 9, 1974 REVERSING TURBINE FLOW DIVIDER 3,620,641 11/1971 Keen et a1 415/217 3,752,597 8/1973 Heinold et al. 4 5/152 Primary Examiner-Henry F. Raduazo Attorney, Agent, ot- Firm-John F. Ahern; James W.
Mitchell 57 ABSTRACT arately adjustable stator blades controlling flow of a motive fluid alternatively to the forward or reversing rotor blades. A divider baffle is disposed between the outer and inner liners of the inlet passage to the adju'stable stator blades. The divider baffle serves to guide. the motive fluid flow to the row of adjustable stator blades being utilized during a selected mode of operation of the turbine. The present invention provides a structure for supporting a divider baffle be-' tween the outer and inner liners of the turbine inlet.
9 Claims, 5 Drawing Figures PATENTEBAPR 9l874 3 802797 sum 1 OF 3 v PATENTED APR 9 I974 SHEET 2 BF 3 FIG.2
PATENTEDAPR slam sum 3 OF 3 FI.G.5
26 AFTER ROTAT ON 42 BEFORE ROTATION 42 AFTER ROTATION .REVERSING TURBINE FLOW DIVIDER SUPPORT BACKGROUND OF THE INVENTION This invention was made under .Contract with the 1 U.S. Government under Contract -35510 with the US. Maritime Administration of the Department of Commerce. The U.S. Government is licensed in accordance with the terms of the aforesaid Contract and has reserved the rights set forth in Section 1( and 1(g) of the Oct. 10, 1963 PresidentialStatement of Government Patent Policy.
The invention relates to an axial flow, two-shaft gas turbine, wherein the load turbine shaft is reversible. More particularly, the inventionis concerned with a structure for supporting a divider baffle at the inlet of the turbine, the divider baffle having thefunction of channeling the motive fluid flow in correspondence to the desired operational mode of the turbine.
It is desirable in some instances to provide an elastic fluid turbine with additional means to reverse the direction of rotation of the output shaft, such as in marine propulsion units where astern operation is necessary. Although gas turbines have been used in a few marine propulsion systems, one of the major problems has been that of providing suitable and economical astern operation. There have been several suggestions for reversing the propeller shaft without reversing the gas turbine shaft. US. Pat. No. 2,912,824 issued to F. H. Van Nest et al. on Nov. 17, 1959, and assigned to the assignee of the present invention, discloses a marine gas turbine powerplant, wherein astern power is provided by a reversible pitch propeller. Other means for obtaining reverse power have included suggestions for fluid or friction clutches withreverse gear or suggestions for intermediate electric drives.
It has been suggested in marine propulsion systems for steam turbines that two concentric rows of blades on a single wheel, one of the rows having reversed curvature, can be employed to obtain forward or reverse rotation of the turbine wheel. However, selective admission of motive fluid to the desired row is easily accomplished under steam turbine practice by means of opening external valves to admit steam through fixed nozzle partitions in a nozzle box. This typeof control of the motive fluid is unsuitable for a gas turbine since the combustion products cannot simply be bottled up in the manner that stearn can. Accordingly, the adjustment of motive fluid power and flow through turbine buckets is conventional axial flow gas turbines is either accomplished by controlling the fuel (in a single shaft gas turbine), or by adjusting the ratio of pressure drops across two independent turbine-stages (in a twoshaft gas turbine) as disclosed in the aforementioned Van Nest patent. A suitable variable area adjustable nozzle to accomplish division of power between stages in a two-shaft gas turbine is disclosed in U.S. Pat. No.
2,919,890 issued to -A. Smith et al. on Jan, 5, 1960,
and also assigned to the assignee of the present invention.
One of the problems encountered in a reversing gas turbine resides in the inlet structure where a motive fluid is to be directed to that rowof separately adjustable stator blades directing motive fluid flow to a corresponding row of rotor blades. US. Pat. No. 3,286,983 issued to G. W. Scheper, Jr. on Nov. 22, 1966, and assigned to the assignee of the present invention, shows a divider baffle extending from an adjacent position of the two rows of separately adjustable stator blades toward the inlet opening. Such a divider baffle directs incoming motive fluid flow to the open row of stator blades while the closed row of stator blades develops a back pressure along one side of the divider baffle. The prior art as seen in the above reference, shows a divider baffle as being supported by struts extending between the outer and inner liners of the inlet passageway. However, the divider baffle is subjected to considerable dynamic loading during operation of the turbine and merely attaching such a divider baffle to the exterior wall of the aforementioned strut has not proven adequate. I
The present invention involves the use of a separate airfoil fairing disposed about the inner radial'portion of each existing strut or support pin. The airfoil fairing includes a unique locking means for attachment to the inner liner of the inlet passage while at the same time having a unique support means at an outer radial portion-thereof for connection with a divider baffle.
Accordingly, one object of the present invention is to provide an improvedstructure'for a reversing gas turbine which includes an improved support for a divider baffle thereof. I
Another object of the invention is to provide an improved structure for' supporting the divider baffle which divider baffle is easily assembled in the turbine.
A further object of the present invention is to provide an improved structure fora reversing gas turbine which adequately provides for all dynamic loading and all thermal expansions and contractions during operation of the turbine.
SUMMARY OF THE INVENTION Briefly stated, the invention comprises a'hollow air- 7 DESCRIPTION OF THE DRAWINGS Other objects and advantages of the present invert-- tion will become apparent from the following description, taken in connection with-the accompanying drawings, in which:
FIG. 1 is a longitudinal view in section of the inlet passage of the turbine. 1
FIG.- 2 is a side view in section of the airfoil fairing in an assembled position. v
' FIG. 3 is an axial view'in section of the-airfoil fairing in an assembled position. FIG. 4 is a top view of the airfoil fairing in its assembled position. Y
FIG. 5 is an assembly drawing for the airfoil fairing.
DESCRIPTION OF ONE EMBODIMENT A second row of adjustable stator blades 18 is separated ,from the stator blades 14 by a spherical, circumferentially extending partition 20. The stator blades 18 are oriented to direct the motive fluid flow against. a second row of rotor blades 22 in a second or reverse mode of operation.
The present invention is directed to a new and improved structure for the divider baffle 24 and the support fairings 26 therefor. The divider baffle24 is in lapped abutment with partition and is supported within the inlet passage by a plurality of airfoil fairings 26. A support pin 28 extends from an outer shell 11 of the turbine through the outer liner 10 of the inlet passage, concentrically through the airfoil fairing 26, through the inner liner 12 of the inlet passage and into a diaphragm 30 of the turbine. The support pins 28 are. well known in the art.
in FIG. 2, the airfoil fairing 26 is shownin cross section in a side view. The support pin 28 includes an in wardly stepped portion 28a for accommodation of the airfoil fairing 26. A lower portion 28b of the support pin 28 is a narrower cylindrical portion extending through concentric apertures 31 and 32 as defined by the inner liner l2 and airfoil fairing 26 respectively. Portion 28b of the support pin 28 engages a mating cavity29 in diaphragm 30 of the turbine. The support pin 28, therefore, serves to transmit moment and shear forces between the diaphragm 30 and the outer shell 1 1 of the turbine. Again referring to FIG. 2, the inner liner 12 includes radial restraining hooks 12a which fit into cooperating cavities 12b in the turbine diaphragm 30.
FIG. 3 is-an axial view in section of the airfoil fairing 26, support pin 28, and the divider baffle 24. For a better understanding of what is shown in FIG. 3, it is to be initially understood from FIG. 4, that the disposition of the major cross sectional axis of the airfoil fairing 26 is oblique or skewed to the turbine longitudinal axis since the direction of the motive fluid flow is oblique to the longitudinal axis of the turbine at this axial location in the turbine. Again referring to FIG. 3, a platform portion 26a of the airfoil fairing 26extends circumferentiallyto engage adjacent segmented portions of the divider baffle 24. The divider baffle 24 comprises a plurality of such circumferentially segmented portions. An airfoil fairing 26 as typically shown in FIG. 3 is disposed between and supports the adjacent segmented portions of the divider baffle 24. Grooves 32 on the platform portion 26a cooperate with circumferentially extending tongues 34 which extend from the segmented portions of the divider baffle 24. Since the cooperating tongue and groove connections are in a disposition parallel to the axis of the turbine, the various segmented portions of the divider baffle 24 may be assembled by axially sliding the tongues 34 of the segmented portions into the grooves 35 in a direction toward the partition 20.
One of the corresponding sides of the platform portions 26a includes a close fitting divider baffle pin 36 and the other side includes a pin 38 allowing for thermal expansion of the divider baffle 24. As further shown in FIGS. 3 and 4, the tongue and groove assembly is thereby maintained in position by use of divider baffle pins 36 and 38. With the clearance fit of the divider baffle pin 38, the platform portions 26a will not be subjected to compression during thermal, circumferential expansion of the segmented portions of divider baffle 24.
FIG. 3 also shows a locking means at the inner radial portion of airfoil fairing 26 by which the latter is secured to the inner liner 12. A cylindrical portion 40 on the airfoil fairing 26 extends concentrically through aperture 31 defined by the inner liner 12. Cylindrical portion 40 further has two spaced lugs 42 protruding from the surface thereof. The lugs 42 engage the slots 44 located on the underside of the inner liner 1 2. The engagement therebetween holds the airfoil fairing 26 in a fixed radial disposition. As shown in FIG. 5, the airfoil fairing 26 is assembled 90 degrees counterclockwise from its final orientation. In this manner, the lugs 42 are aligned with loading holes 43 in the inner liner 12. This breech loading of the airfoil fairing through the inner liner 12 provides for the lugs 42 to be aligned with corresponding slots 44. After the airfoil fairing 26 has been loaded through the inner liner 12, the airfoil fairing 26 is assembled in its final position by rotating the fairing 90 degrees in a clockwise direction as shown in FIG. 5. Upon rotation, the lugs 42 necessarily rotate to become engaged with the corresponding slots 44.
Asfurther seen in FIGS. 3 and 5, a locking means pin 46 is inserted through the inner liner l2 and an aligned notch in one of the lugs 42. With the pin 46 affixed in place, the airfoil fairing 26 is locked against rotation.
The final structural aspect of the divider baffle support assembly includes a plurality of supportpads 48. as shown in FIGS. 2, 3, and 5. The support pads 48 extend from the inner surface of the airfoil fairing 26 and present a close tolerance fit with respect to the support pin 28. In this manner, dynamic loading on the airfoil fairing 26 is effectively transmitted to the support pin 28.
Furthermore, the support pin 28 can be concentrically maintained within the airfoil fairing 26 without having to machine a close tolerance fit between the entire adjacent external surface of the support pin and internal surface of the airfoil fairing 26.
The divider baffle defines alternative passages for a flow medium whereby an operator. may selectively direct the motive fluid flow to the first or second row of rotor blades to effect a first or ahead mode of operation or a second or reverse mode of operation. When the turbine is in its first or' ahead mode of operation, incoming motive fluid flows between the upper surface of the divider baffle 24 and outer liner 10 through the open stator blades 14 to the rotor blades. In this mode of operation, the stator blades 18 are held closed by actuating arms 19 in a manner well known in the art. In the second or reverse mode of operation of the gas turbine, the stator blades 14 are positioned and held closed by actuating arms 21 in a manner well known in the art, and stator blades 18 are open. in the reverse mode of operation, the motive fluid flow flows between theunder surface of divider baffle 24 and inner liner 12 through the open stator blades 18 to the rotor blades 22.
It is to be appreciated that substantial dynamic loading takes place on the divider baffle 24 and therefore the divider baffle 24 requires a correspondingly sufficient amount of support within the inlet passage which support is provided by the new and improved structure shown herein.
While there is shown one embodiment of the invention herein, it is, of course, understood that various modifications may be made, and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.
What is claimed as new and desired to be secured by Letters Patent of the United States is:
1. ln a reversing turbine having outer and inner concentric liners for confining a motive fluid flow, the turbine further having a divider baffle intermediate the outer and inner liners, the divider baffle thereby providing alternative flow paths for directing the motive fluid flow respectively for an ahead mode of operation and a reverse mode of operation of the turbine, a divider baffle support assembly comprising:
a support pin, said support pin extending radially between the outer and inner liners and through the divider baffle;
an airfoil fairing disposed about said support pin; and
said airfoil fairing including locking means at an inner portion thereof, said locking means locking said airfoil fairing in a mounted position on said ferentially segmented portions.
4. The divider baffle'support assembly according to claim 3 wherein said platform portion and each said adjacent ones of said circumferentially segmented portions include cooperating tongue and groove'means for joining said platform portion and each said adjacent ones of said circumferentially segmented portions.
5. The divider baffle support assembly according to claim 4 wherein:
said locking means includes a cylindrical portion,
said cylindrical portion extending radially inward;
at least one lug, said lug protruding from the surface of said cylindrical portion; and
a mounting aperture defined by said inner liner, said mounting aperture receiving said cylindrical portion and said lug to lock said airfoil fairing in its mounted position.
6. The divider baffle support assembly according to claim 5 wherein each said tongue and groove means is substantially parallel to the axis of the turbine.
7. The divider baffle support assembly according to claim 5 further including divider baffle pins, said divider baffle pins engaging and securingsaid tongue .and groove means together.
8. The divider baffle support assembly according to claim 5 further including a locking means pin, said locking means pin engaging and securing said lug and said inner liner together. i
9. The divider baffle support assembly according to claim'S further including a plurality of support pads,
said support pads being disposed between said support