Patent Publication Number: US-9885369-B2

Title: Variable vane for gas turbine engine

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 13/340,983, filed Dec. 30, 2011, entitled “Variable Vane for Gas Turbine Engine”, which claims the benefit of provisional U.S. Patent Application No. 61/428,768 filed Dec. 30, 2010. All of the above listed applications are hereby incorporated by reference herein in their entireties. 
    
    
     REFERENCE REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     The present inventions were made with U.S. Government support under contract number F33615-03-D-2357 DO0010 awarded by the United States Air Force. The United States Government may have certain rights in the present application. 
    
    
     BACKGROUND 
     The present invention relates generally to turbomachinery. The present invention more particularly but not exclusively relates to turbine engines having variable vanes. Many turbine engines include axial compressors and/or turbines with staged rotors and stators. In some circumstances, it is desirable to have stator vanes that can change orientation, for example by rotating the vanes. Vanes are sometimes rotated by fixing a cantilever to a shaft, or spindle, which is attached to the vane. The spindle experiences torsional, compressive, and bending stresses, and often at a high material temperature. The combinations of stress on the spindle can reduce reliability and/or durability, or require a more expensive or robust spindle than would be required in a simpler stress environment. Accordingly, there is a demand for further improvements in this area of technology. 
     SUMMARY 
     According to a first aspect, a turbomachine includes a vane, a rotation support coupled to an end of the vane, and a spindle coupled to the rotation support. The spindle, the vane, and the rotation support are rotationally aligned. An annular sleeve defines the spindle. The annular sleeve contacts the rotation support at a radially inward extent and contacts a turbine casing at a radially outward extent. A first rolling element engages the annular sleeve substantially near the radially outward extent. The first rolling element is coupled to the turbine casing. A second rolling element engages the annular sleeve substantially near the radially inward extent. The second rolling element is coupled to an outer endwall ring. A center of mass of the annular sleeve is positioned between the first and second rolling elements. 
     According to another aspect, a method includes providing a turbomachine comprising a vane, a rotation support coupled to an end of the vane, and a stem coupled to the rotation support. The stem, the vane, and the rotation support are rotationally aligned. The turbomachine further comprises an annular sleeve defining the stem. The annular sleeve contacts the rotation support at a radially inward extent and contacts a turbine casing at a radially outward extent. The turbomachine further comprises a first rolling element engaging the annular sleeve substantially near the radially outward extent. The first rolling element is coupled to the turbine casing. The turbomachine further comprises a second rolling element engaging the annular sleeve substantially near the radially inward extent. The second rolling element is coupled to an outer endwall ring. A center of mass of the annular sleeve is positioned between the first and second rolling elements. The turbomachine further comprises a cantilever affixed to an end of the stem opposite the rotation support, wherein the cantilever is structured to translate rotational force to the stem. The method further includes rotating the cantilever to control a rotational position of the vane. 
     According to yet another aspect, an apparatus includes a turbomachine that includes at least one compression stage and at least one vane. A vane outer button is coupled to a radially outward end of the vane. A spindle is coupled to the vane outer button. The spindle, the vane, and the vane outer button are rotationally aligned. An annular sleeve defines the spindle. The annular sleeve contacts the vane outer button at a radially inward extent and contacts a turbine casing at a radially outward extent. A first rolling element engages the annular sleeve substantially near the radially outward extent. The first rolling element is coupled to the turbine casing. A second rolling element engages the annular sleeve substantially near the radially inward extent. The second rolling element is coupled to an outer endwall ring. A center of mass of a system of the annular sleeve and the spindle is positioned between the first and second rolling elements. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of a portion of a turbomachine. 
         FIG. 2  is a schematic diagram of an apparatus including a variable vane. 
         FIG. 3  is a schematic diagram of a spindle, vane outer button, and annular sleeve. 
     
    
    
     DETAILED DESCRIPTION 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, and any alterations and further modifications in the illustrated embodiments, and any further applications of the principles of the invention as illustrated therein as would normally occur to one skilled in the art to which the invention relates are contemplated and protected. 
       FIG. 1  is a schematic diagram of a portion of a turbomachine  100 , which may be included as part of a gas turbine engine. The turbomachine  100  includes at least one turbine stage and at least one vane  102 . In the illustration of  FIG. 1 , a first rotor  104  is of a high pressure turbine (HPT), and a second rotor  106  is a part of a low pressure turbine (LPT). In the embodiment of  FIG. 1 , the vane  102  is a variably positioned vane able to rotate about an axis  108 . The vane  102  may be one of a multiplicity of vanes on a stator stage following a rotor stage, and the turbomachine  100  may include stages. In one embodiment, a vane  102  may also be located in front of the high pressure turbine. In further embodiments, the vane  102  can be used in a compressor of a gas turbine engine. Further details of certain embodiments are described in greater detail in the section referencing  FIG. 2 . 
       FIG. 2  is a schematic diagram of an apparatus  200  including a variable vane  102 . In certain embodiments, the apparatus  200  includes a vane outer button  202  coupled to the vane  102 . In certain embodiments, the vane outer button  202  is coupled to a radially outward  206  end of the vane  102 . Radially outward  206 , as used herein, refers to the radial direction relative to a radial center (not shown) of a turbomachine  100  including the apparatus  200 , where radially inward  208  is a direction toward the radial center and radially outward  206  is a direction away from the radial center. The vane outer button  202  may be a rotating support for a stem (e.g. a spindle  204 ) coupled to the vane outer button  202  and rotationally fixed to the vane  102 . In certain embodiments, the spindle  204  is any component fixed to the vane  102  in a manner such that when the spindle  204  is rotated a known degree of rotation the vane  102  also rotates a similar amount of rotation. In certain embodiments, the spindle  204  and vane  102  rotate together through an identical angle of rotation, although any fixed relationship between the rotation angles is contemplated herein. 
     In certain embodiments, an annular sleeve  210  engages the vane outer button  202  at a first end  212 , and the annular sleeve  210  engages the spindle  204  at a second end  214 . An end of the annular sleeve  210  as used herein includes any location of interest on the annular sleeve  210  at, near, and/or facing a geometric end. For example, the annular sleeve  210  in  FIG. 2  includes a first end  212  engaging the vane outer button  202 , and a second end  214  engaging the spindle  204 , where the second end  214  also engages a turbine casing  216 . In certain embodiments, the annular sleeve  210  contacts the vane outer button  202  at a radially inward  208  extent of the annular sleeve  210  as shown in  FIG. 2 . In certain embodiments, the annular sleeve  210  contacts the turbine casing  216  at a radially outward  206  extent of the annular sleeve  210  as shown in  FIG. 2 . 
     In certain embodiments, the annular sleeve  210  includes a cross-sectional wall portion  218  having an aperture  220 , and the annular sleeve  210  engages the spindle  204  where the spindle  204  extends through the aperture  220 . In certain embodiments, a nut  222  engages the annular sleeve  210  with the spindle  204 . For example, the nut  222  engages threads on the spindle  204  and applies force to the wall portion  218  toward the radially inward  208  extent of the annular sleeve  210 . In certain embodiments, the wall portion  218  is perpendicular to the spindle  204 , although other configurations of the wall portion  218  may be utilized. 
     In certain embodiments, the spindle  204  includes a radially outward end  224  that extends through the turbine casing  216 , and a cantilever rotation actuator  226  is coupled to the radially outward end  224  of the spindle  204 . In certain embodiments, the cantilever  226  is affixed to the spindle  204 , for example by a nut  228  holding the cantilever  226  against the turbine casing  216 . In certain embodiments, the cantilever  226  translates rotational force to the spindle  204 . 
     In certain embodiments, the apparatus  200  includes a first bearing  230  coupled to the turbine casing  216  and a second bearing  232  coupled to an endwall outer ring  234 . In certain embodiments, the first bearing  230  and second bearing  232  rotatably engage the annular sleeve  210 . 
     In certain further embodiments, the apparatus  200  further includes an inboard rotating support, which may be a vane inner button  236 , coupled to the vane  102 , and a third bearing  238  coupled to an endwall inner ring  240 . The third bearing  238  rotatably engages the vane inner button  236 . The vane inner button  236 , in certain embodiments, is coupled to the vane  102  at a radially inward portion of the vane  102 . The endwall inner ring  240  may be split as shown in the illustration of  FIG. 2 , although the endwall inner ring  240  may be configured in any manner including, without limitation, not-split, and integral. 
     In certain further embodiments, the bearings  230 ,  232 ,  238  may be roller element bearings, and the roller elements may further include ceramic roller elements. In certain embodiments, the roller elements do not require lubrication. In certain embodiments, the first bearing  230  includes a rolling element engaging the annular sleeve substantially near the radially outward  206  extent of the annular sleeve, and the second bearing  232  includes a rolling element engaging the annular sleeve substantially near the radially inward  208  extent of the annular sleeve. As used herein, substantially near the radially outward  206  and radially inward  208  extent includes embodiments wherein the bearings  230 ,  232  are placed at a maximal distance apart as allowed by space constraints, but also includes embodiments wherein a center of mass of the annular sleeve  210  or a center of mass of the system of the annular sleeve  210  and spindle  204  is positioned between the bearings  230 ,  232 . In certain embodiments, the apparatus  200  includes at least two bearings  230 ,  232  that engage the annular sleeve  210  and at least one bearing  238  that engages the vane inner button  236 . 
     In certain embodiments, the annular sleeve  210  includes an annular sleeve wall aperture  243  that allows cooling fluid, such as but not limited to a cooling air, to enter the annular sleeve  210 . For ease of convenience below, the cooling fluid may be referred to as a cooling air but no limitation is intended of the cooling fluid to be limited to an air composition. The apparatus  200  may further include at least one opening  242  in the vane outer button  202  that allows cooling air to continue and flow into the vane  102 . The vane  102 , in certain embodiments, is at least partially hollow and is structured to allow the cooling air to enter the vane  102 . In certain embodiments, the cooling air flows through an opening  244  in the vane inner button  236  and out of the vane  102 . In certain embodiments, the cooling air flows out of a trailing edge opening (not shown) of the vane  102  and exits the vane  102  into a flowing gas stream  246  in the turbomachine  100 . The cooling air may include any type of cooling fluid, and further the flow of the cooling air may be in any direction, including from the vane inner button  236 , through the vane  102 , and exiting the vane  102  through the vane outer button  202 . In some embodiments various structures such as the vane  102  may not be cooled by a cooling fluid. 
     In certain embodiments, any combination or sub-combination of the spindle  204 , vane outer button  202 , vane  102 , and vane inner button  236  may be coupled by attachment or formed integrally. Attachment may include welding, bolting, or any other joining mechanism. In certain embodiments, the vane outer button  202  is integrally formed with at least one of the spindle  204 , the annular sleeve  210 , and the vane  102 . 
       FIG. 3  is a schematic diagram of a portion of an apparatus  300  including a spindle  204 , a vane outer button  202 , and an annular sleeve  210 . The annular sleeve  210  has an outer diameter  302  that is greater than a spindle diameter  304 . In certain embodiments, the outer diameter  302  is much greater than the spindle diameter  304 . In certain embodiments, the outer diameter  302  is approximately equal to a perpendicularly projected diameter of the vane outer button  202  as illustrated in  FIG. 3 . In certain embodiments, the outer diameter  302  is at least two times greater, and in certain further embodiments at least three times greater, than the spindle diameter  304 . 
     In certain embodiments, the spindle  204  includes an axial length  306 . The spindle  204  in  FIG. 3  begins at a lower position  310 . In certain embodiments, the annular sleeve  210  engages the spindle  204  at about a mid-point  308  of the spindle  204 . In certain embodiments, the annular sleeve  210  engages the spindle  204  at a position between 25 percent and 75 percent (between the defined positions  312 ) of an axial distance along the axial length  306 . The engagement positions listed are examples only, and any engagement position that sufficiently reduces bending stress on the spindle  204  from the actuation of the cantilever  226  is contemplated herein. One of skill in the art, having the benefit of the disclosures herein, can readily determine engagement positions that are sufficiently separated with simple empirical testing to provide the selected stress reduction or selected durability of the spindle  204  for a particular application. 
     As is evident from the text and figures presented above, a variety of embodiments according to the present invention are contemplated. 
     An exemplary set of embodiments is an apparatus including a vane, a rotation support coupled to an end of the vane, a spindle coupled to the rotation support, wherein the spindle, the vane, and the rotation support are rotationally aligned, and an annular sleeve engaging the rotation support at a first end and engaging the spindle at a second end. The exemplary apparatus further includes an annular sleeve that engages the spindle at about a mid-point of the spindle. In certain embodiments, the apparatus includes a first bearing coupled to an endwall outer ring and a second bearing coupled to a turbine casing, where the first and second bearings rotatably engage the annular sleeve. In certain further embodiments, the first and second bearings are ceramic rolling elements. In certain embodiments, the apparatus further includes an inboard rotating support coupled to the vane, the apparatus further comprising a third bearing coupled to a split inner endwall ring, and wherein the third bearing rotatably engages the inboard rotating support. 
     In certain embodiments, the annular sleeve further includes a cross-sectional wall having an aperture, where the spindle extends through the aperture, and where a nut threaded on the spindle engages the annular sleeve with the spindle. In certain embodiments, the apparatus includes a cantilever affixed to an end of the spindle opposite the rotation support, where the cantilever translates rotational force to the spindle. In certain embodiments, the rotational support is integrally formed with at least one member selected from the group consisting of the spindle, the annular sleeve, and the vane. In certain embodiments, the annular sleeve has an outer diameter at least three times greater than a diameter of the spindle. 
     Another exemplary set of embodiments includes a turbomachine having a variably positioned vane, an outer spindle integral with a vane outer button, where the vane is coupled to the vane outer button, an annular sleeve defining the spindle, wherein the annular sleeve contacts the vane outer button at a radially inward extent and contacts a turbine casing at a radially outward extent. In certain embodiments, the annular sleeve includes a wall portion positioned perpendicular to the spindle, where the wall portion includes an aperture and the spindle extends through the aperture, and where the spindle includes threads. In certain embodiments, a nut engages the threads, where the nut applies force to the wall portion toward the radially inward extent, a radially outward end of the spindle extends through the turbine casing, and a cantilever rotation actuator is coupled to the radially outward end of the spindle. In certain embodiments, a first rolling element engages the annular sleeve substantially near the radially outward extent, where the first rolling element is coupled to the turbine casing, and a second rolling element engages the annular sleeve substantially near the radially inward extent, where the second rolling element is coupled to an outer endwall ring. 
     In certain embodiments, the turbomachine further includes a vane inner button coupled to the vane at a radially inward portion of the vane, a third rolling element engages the vane inner button, and the third rolling element rotatably engages the vane inner button. In certain embodiments, the turbomachine includes an annular sleeve wall aperture and a vane outer button aperture(s), where the sleeve wall aperture and the vane outer button aperture are structured to allow cooling air to enter the vane. In certain embodiments, the annular sleeve has an outer diameter at least two times greater than a diameter of the spindle. 
     Yet another exemplary set of embodiments is a method including an operation to provide a turbomachine. The provided turbomachine includes a vane, a rotation support coupled to an end of the vane, a stem coupled to the rotation support, where the stem, the vane, and the rotation support are rotationally aligned, an annular sleeve engaging the rotation support at a first end and engaging the stem at a second end, and a cantilever affixed to an end of the stem opposite the rotation support, where the cantilever is structured to translate rotational force to the stem. The exemplary method further includes rotating the cantilever to control a rotational position of the vane. 
     In certain embodiments, the provided turbomachine further includes an opening formed in a sidewall of the annular sleeve and an opening(s) formed in the rotational support, where the opening formed in the rotational support is exposed to an inside of the vane, and the method further includes flowing a cooling gas stream through the opening formed in a sidewall of the annular sleeve, through the opening(s) formed in the rotational support and into the vane. A further exemplary embodiment of the method includes flowing the cooling gas stream through an opening in a trailing edge of the vane. 
     In certain embodiments, the turbomachine further includes a vane inner button coupled to the vane, the vane inner button having an opening exposed to the inside of the vane, and the method further includes flowing the cooling gas stream through the opening in the vane inner button. In certain embodiments, the turbomachine further includes a first bearing coupled to an endwall outer ring and a second bearing coupled to a turbine casing, where the first and second bearings rotatably engage the annular sleeve. In certain further embodiments, the turbomachine further includes an inboard rotating support coupled to the vane and a third bearing coupled to a split inner endwall ring, and the third bearing rotatably engages the inboard rotating support. In certain embodiments, the annular sleeve includes an outer diameter at least two times greater than a diameter of the stem. 
     Yet another exemplary set of embodiments is an apparatus including a turbomachine having at least one compression stage and at least one vane, a vane outer button coupled to a radially outward end of the vane, a spindle coupled to the vane outer button, wherein the spindle, the vane, and the vane outer button are rotationally aligned, and an annular sleeve engaging the vane outer button at a first end and the spindle at a second end. In certain embodiments, the apparatus further includes annular sleeve having an outer diameter that is much greater than a diameter of the spindle, and/or the annular sleeve having an outer diameter that is at least three times greater than a diameter of the spindle. 
     In certain embodiments, the spindle includes an axial length, and the annular sleeve engages the spindle at a position between 25 percent and 75 percent of an axial distance along the axial length. In certain embodiments, the annular sleeve includes a cross-sectional wall portion having an aperture, and the annular sleeve engages the spindle where the spindle extends through the aperture. In certain embodiments, the vane outer button is integrally formed with the spindle, the annular sleeve, and/or the vane. In certain embodiments, the apparatus further includes at least two rotating element bearings structured to engage the annular sleeve. In certain embodiments, the apparatus further includes a vane inner button coupled to a radially inward end of the vane and an inner rotating element bearing structured to engage the vane inner button. 
     While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the inventions are desired to be protected. It should be understood that while the use of words such as preferable, preferably, preferred, more preferred or exemplary utilized in the description above indicate that the feature so described may be more desirable or characteristic, nonetheless may not be necessary and embodiments lacking the same may be contemplated as within the scope of the invention, the scope being defined by the claims that follow. In reading the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary.