Abstract:
A method of assembling a rotor assembly is provided. The method comprises forming at least one channel in a dovetail portion of at least one rotor blade assembly, wherein the rotor blade assembly includes an airfoil extending outwardly from the dovetail portion, inserting a sealing assembly within the at least one channel of the dovetail portion, and coupling the at least one rotor blade assembly to a rotor disk using the dovetail portion such that at least a portion of the sealing assembly is between the dovetail portion and the rotor disk.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates generally to gas turbine engines, and more specifically to methods and apparatus for assembling gas turbine engine components. 
         [0002]    Accurate fabrication of engine components may be a significant factor in engine performance and engine efficiency. Specifically, when the component is a gas turbine engine blade, the fabrication of the blade may affect the overall performance and efficiency of the gas turbine engine. At least some known gas turbine engines include high and low pressure compressors, a combustor, and at least one turbine. The compressors compress air which is mixed with fuel and channeled to the combustor. The fuel/air mixture is then ignited to generate hot combustion gases, which are channeled to the turbine. At least some known turbines include a rotor assembly that includes at least one row of circumferentially-spaced rotor blades. Each rotor blade includes an airfoil that includes a pressure side coupled to a suction side at a leading edge and a trailing edge. Each airfoil extends radially outward from a rotor blade platform. At least some known rotor blades include a dovetail that extends radially inward from a shank coupled to the platform. The dovetail is used to mount the rotor blade within the rotor assembly to a rotor disk or spool. In at least some known gas turbine engines, a small gap may be defined between a lower surface of the dovetail and a lower surface of the rotor disk. 
         [0003]    During operation, a pressure differential created between the rotor blade pressure side and the rotor blade suction side may result in an undesirable leakage flow between the upstream and downstream portions of the rotor. One such possible leakage path may be defined through the gap defined between the dovetail and the lower surface of the rotor disk groove in which the rotor blades are carried. If such leakage paths are not efficiently sealed, the leakage flow may have an adverse effect both on engine efficiency and engine performance. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0004]    In one aspect, a method of assembling a rotor assembly is provided. The method comprises forming at least one channel in a dovetail portion of at least one rotor blade assembly, wherein the rotor blade assembly includes an airfoil extending outwardly from the dovetail portion, inserting a sealing assembly within the at least one channel of the dovetail portion, and coupling the at least one rotor blade assembly to a rotor disk using the dovetail portion such that at least a portion of the sealing assembly is between the dovetail portion and the rotor disk. 
         [0005]    In another aspect, a blade assembly for use in a turbine engine is provided. The blade assembly comprises an airfoil, a dovetail, a platform extending between the dovetail and the airfoil, the dovetail comprising at least one channel defined in a lower surface of the dovetail, and a sealing assembly inserted within the at least one channel, the sealing assembly configured to facilitate sealing between the dovetail and a rotor disk. 
         [0006]    In a further aspect, a sealing assembly is provided. The sealing assembly comprises a dynamic plate that is substantially U-shaped, the dynamic plate comprises a front surface comprising at least one contoured edge and a channel, a static plate slidably coupled to the dynamic plate wherein the static plate is substantially U-shaped, the static plate comprising an inner surface and a perimetrical flange coupled thereto and extending axially therefrom, the flange comprises an outer surface that is slidably coupled to the channel of the dynamic plate, and a rope seal removably coupled to the flange outer surface wherein the rope seal is substantially U-shaped. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a schematic illustration of an exemplary gas turbine engine. 
           [0008]      FIG. 2  is an enlarged cross-sectional view of a portion of the engine shown in  FIG. 1 . 
           [0009]      FIG. 3  is an end view of an exemplary gas turbine engine blade coupled to a disk which may be used with the engine shown in  FIG. 1 . 
           [0010]      FIG. 4  is a cross-sectional side view of a portion of the blade shown in  FIG. 3 . 
           [0011]      FIG. 5  is a perspective view of a sealing apparatus that may be used with the blade shown in  FIG. 4 . 
           [0012]      FIG. 6  is a cross-sectional view of the sealing apparatus shown in  FIG. 5  and coupled to the blade shown in  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    The present invention generally provides exemplary methods and apparatus for assembling a gas turbine engine. The embodiments described herein are not limiting, but rather are exemplary only. Although the present invention is described below in reference to its application in connection with a gas turbine engine, it should be apparent to those skilled in the art and guided by the teachings herein provided that with appropriate modification, the system and methods of the present invention can also be suitable for any engine, including, but not limited to, steam turbine engines. Moreover, it should be apparent to those skilled in the art that the present invention may apply to any type of rotor blade, such as, but not limited to, compressor rotor blades and/or turbine rotor blades. More specifically, the present invention may apply to any rotor blade where preventing the leakage of airflow between a gap defined between a rotor blade dovetail and a lower surface of a rotor disk is desired. 
         [0014]    As used herein, the terms “manufacture” and “manufacturing” may include any manufacturing or fabrication process. For example, manufacturing processes may include grinding, finishing, polishing, cutting, machining, inspecting, and/or casting. The above examples are intended as exemplary only, and thus are not intended to limit in any way the definition and/or meaning of the terms “manufacture” and “manufacturing”. In addition, as used herein, the term “component” may include any object to which a manufacturing process is applied. Furthermore, although the invention is described herein in association with a turbine engine, and more specifically for use with a rotor blade for a turbine engine, it should be understood that the present invention may be applicable to any component and/or any manufacturing process. Accordingly, practice of the present invention is not limited to the manufacture of rotor blades or other components of gas turbine engines. 
         [0015]      FIG. 1  is a schematic illustration of an exemplary turbine engine  10  having a longitudinal axis  11 , and including a core turbine engine  12  and a fan section  14  coupled upstream of core engine  12 . Core engine  12  includes an outer casing  16  that defines an annular core engine inlet  18 . Casing  16  circumscribes a low-pressure booster  20  used to increase the pressure of incoming air to a first pressure level. 
         [0016]    A high pressure, multi-stage, axial-flow compressor  22  receives pressurized air from booster  20  and further increases the pressure of the air to a second, higher pressure level. The high pressure air flows to a combustor  24  and is mixed with fuel. The fuel-air mixture is ignited to raise the temperature and energy level of the pressurized air. Combustion products generated are channeled to a first turbine  26  for driving compressor  22  through a first drive shaft  28 , and subsequently to a second turbine  30  for driving booster  20  through a second drive shaft  32 . Spent combustion gases are discharged from core engine  12  through an exhaust nozzle  34 . 
         [0017]    Fan section  14  includes a rotatable, axial-flow fan rotor  36  that is driven by second turbine  30 . A fan casing  38  circumscribes fan rotor  36  and is supported from core engine  12  by a plurality of circumferentially-spaced support struts  44 . Fan rotor  36  includes a plurality of circumferentially-spaced fan blades  42 . Fan casing  38  extends rearwardly from fan rotor  36  over an outer portion of core engine  12  to define a secondary, or bypass airflow conduit. A casing element  39  that is downstream of and connected with fan casing  38  supports a plurality of fan stream outlet guide vanes  40 . The air that passes through fan section  14  is propelled downstream by fan blades  42  to provide additional propulsive thrust to supplement the thrust provided by core engine  12 . 
         [0018]      FIG. 2  is an enlarged, cross-sectional view of a portion of exemplary second turbine  30 . In the exemplary embodiment, turbine  30  includes a plurality of stages  46  that each includes a plurality of stator sections  52  and a plurality of rotor sections  49 . Stator sections  52  each include a plurality of radially-extending, circumferentially-spaced stator vanes  47 . Rotor sections  49  include a plurality of radially-extending, circumferentially-spaced rotor blades  48  coupled to a plurality of rotor disks  56 . In the exemplary embodiment, rotor disks  56  include a plurality of circumferentially-spaced, axially-extending dovetail slots  50  that are configured to receive a corresponding plurality of rotor blades  48 . 
         [0019]    In the exemplary embodiment, turbine  30  also includes an inlet  66  that defines a flow passageway  67  through which combustion products may pass. An outer boundary of the flow passageway is defined by an outer annular casing  70  and an inner boundary of the flow passageway is defined by the blade platforms  120  of rotor blades  48  and also by a stationary annular seal ring  72 . 
         [0020]    In the exemplary embodiment, each stator section  52  includes an annular abradable seal (not shown) that is coupled to a respective annular sealing ring  72 . The seal is oriented to be engaged by respective labyrinth seals (not shown) coupled to rotor disk  56  to facilitate minimizing air leakage around stators  52 . Sealing rings  72  also facilitate restricting the flow of air to flow passageway  67 . 
         [0021]      FIG. 3  is an end view of rotor disk  56  including a single rotor blade  48  coupled therein.  FIG. 4  is a cross-sectional view of a portion of rotor blade  48 . In the exemplary embodiment, rotor blades  48  each include a base portion  100 , an airfoil portion  122 , and a platform  120  extending therebetween. Specifically, in the exemplary embodiment, base portion  100  includes a dovetail  110 . Platform  120  includes an upper surface  119  that is coupled to airfoil portion  122 . Airfoil portion  122  extends radially outward from surface  119 , into the flow path defined within engine  10 . 
         [0022]    In the exemplary embodiment, dovetail slots  50  are sized and shaped to receive rotor blades  48  therein. Specifically, slots  50  are sized and shaped to receive each rotor blade dovetail  110  therein. In the exemplary embodiment, slot  50  has a generally cross-sectional shape that is complimentary to the cross-sectional shape of the dovetail  110 . Moreover, in the exemplary embodiment, slot sidewalls  84  and  86  are spaced apart from each other. In the exemplary embodiment, each sidewall  84  and  86  includes a respective inward convex projection  88  and  90 , and a pair of recesses  112  and  114  that partially define the cross-sectional shape of slot  50 . 
         [0023]    In the exemplary embodiment, dovetail  110  includes a radially inner surface  115  and a pair of contoured sidewalls  116  and  118  that are spaced circumferentially from each other. Sidewalls  116  and  118  are shaped to receive the inwardly-extending convex projections  88  and  90  of rotor slot  50  where dovetail  110  is inserted in slot  50 . More specifically, in the exemplary embodiment, when dovetail  110  is within slot  50 , a gap  144  is defined between radially inner surface  115  of dovetail  110  and slot base  82 . As described in more detail below, air leakage from one stage  46  to an axially-adjacent downstream stage  46  may undesirably flow through gap  144 . In an alternative embodiment, an amount of aluminum may be applied to dovetail  110  and slot base  82  to facilitate reducing air leakage through gap  144 . In such an embodiment, the aluminum may be applied using a spraying technique. Moreover, in such an embodiment, sprayed aluminum may have a thickness that is variable and therefore may not completely seal gap  144 . Furthermore, the amount of sprayed aluminum used may add additional cost to the assembly of engine  10 . 
         [0024]    In the exemplary embodiment, rotor blade  48  includes a cavity  142  defined within dovetail  110 . Cavity  142  receives cooling air (not shown) therein to facilitate cooling rotor blades  48 . 
         [0025]    In the exemplary embodiment, dovetail  110  also includes two channels  130  defined therein. More specifically, channels  130  are formed in dovetail  110  using either of electro discharge machining (“EDM”) or electro chemical machining (“ECM”). Alternatively, channels  130  may be formed in dovetail  110  using any suitable known machining methods. Channels  130 , as described in more detail below, are sized and oriented to receive a sealing assembly  200  (shown in  FIGS. 2 and 3 ) therein, and each include a recessed surface  132  that includes a radially inner sliding surface  140 , a radially outer surface  134 , an axially outer surface  136 , and an axially inner surface  138 . More specifically, in the exemplary embodiment, channels  130  are formed such that a radially inner surface  140  of recessed surface  132  is oriented at an oblique angle θ with respect to radially inner surface  115  of dovetail  110 . As described in more detail below, angle θ is determined as a function of a mass of a dynamic plate  202 , the ductile characteristics of a rope seal  206 , the pressure of air within the particular stage  46 , and the size of gap  144 . More specifically, in the exemplary embodiment, angle θ is selected to facilitate dynamic plate  202  loading rope seal  206  such that gap  144  is substantially sealed by rope seal  206 . 
         [0026]      FIG. 5  is a perspective view of sealing assembly  200 . In the exemplary embodiment, sealing assembly  200  includes dynamic plate  202 , a static plate  204 , and rope seal  206 . In the exemplary embodiment, dynamic plate  202  is generally U-shaped and generally includes a plurality of surfaces. Specifically, in the exemplary embodiment, dynamic plate  202  is defined by a front surface  210 , a rear surface  212 , an inner surface  214 , an outer surface  222 , and a pair of end surfaces  216 . More specifically, in the exemplary embodiment, front surface  210  includes a contoured edge  218  that extends about an outer periphery of front surface  210  and has a generally U-shape. In one embodiment, contoured edge  218  may include, but not limited to, a chamfered edge, a rounded edge, a cam surface edge, or a splined contoured edge surface. In the exemplary embodiment, front surface  210  also includes a U-shaped channel  220  defined therein. Similarly, in the exemplary embodiment, static plate  204  has a generally U-shape and includes an inner surface  226  and a perimetrical flange  228  that extends outward therefrom. Perimetrical flange  228  includes an outer surface  230 . Rope seal  206  includes an exterior surface  234  and a pair of end surfaces  236 . In the exemplary embodiment, rope seal  206  is substantially cylindrical. Alternatively, rope seal  206  may have any shape that enables sealing assembly  200  to function as described herein, such as, but not limited to, a rectangular cross-sectional shape and/or a semi-circular cross-sectional shape. As described in more detail below, in the exemplary embodiment, rope seal  206  is fabricated from a material that enables rope seal  206  to be deformed by the application of force by dynamic plate  202 . Such as, for example, a ductile metal that may deform. 
         [0027]    In the exemplary embodiment, sealing assembly  200  is assembled by coupling static plate  204  to dynamic plate  202  such that flange  228  is slidably coupled within channel  220 . Specifically, in the exemplary embodiment, dynamic plate  202  is configured to receive perimetrical flange  228  of static plate  204 . Moreover, in the exemplary embodiment, rope seal  206  is coupled to static plate outer surface  230 . Once assembled, sealing assembly  200  is inserted within channel  130  such that dynamic plate inner surface  214 , static plate inner surface  226 , and rope seal exterior surface  234  are each slidably coupled against channel recessed surface  132 . Moreover, in the exemplary embodiment, dynamic plate end surfaces  216  and rope seal end surfaces  236  are slidably coupled against radially outer surface  134 . 
         [0028]      FIG. 6  is an enlarged cross-sectional view of a portion of rotor blade  48  and channel  130  with sealing assembly  200  inserted therein. In  FIG. 6 , a portion of rope seal  206  has been removed for clarity. In the exemplary embodiment, dynamic plate  202  induces a load force on rope seal  206  and channel outer surface  136 . As described in more detail below, in the exemplary embodiment, contoured edge  218  of dynamic plate  202  displaces rope seal  206  from static plate outer surface  230  such that rope seal  206  substantially seals gap  144 . As a result, rope seal  206  facilitates preventing air leakage from flowing through gap  144  which further facilitates improving engine efficiency. 
         [0029]    In the exemplary embodiment, sealing assembly  200  and/or recessed surface  132  may be coated with a lubricant to facilitate sliding sealing assembly  200  along recessed surface  132 . Moreover, in the exemplary embodiment, the lubricant may be a dry film lubricant (“DFL”). Specifically, in the exemplary embodiment, the DFL may be any suitable DFL including, but not limited to, molybdenum disulfide, graphite, or polytetrafluoroethylene (“PTFE”) (e.g., available from DuPont of Wilmington, Del. under the name TEFLON® fine powder resin). 
         [0030]    As described in more detail below, the lubricant facilitates sliding sealing assembly  200  along recessed surface  132  such that sealing assembly  200  shifts generally outward along surface  132  during engine  10  operation, and shifts generally inward along surface  132  when engine  10  is not operating. Specifically, the DFL reduces a coefficient of friction between sealing assembly  200  and recessed surface  132 . In an alternative embodiment, the lubricant may enable sealing assembly  200  to only slide generally outward along recessed surface  132  during a first operation of engine  10 , following the installation of rotor blade  48 , including sealing assembly  200 , within engine  10 . In such an embodiment, the lubricant facilitates sliding sealing assembly  200  generally outward along recessed surface  132  into a sealing position, as described below. Specifically, in such an embodiment, as operating temperatures of engine  10  increases, the lubricant may oxidize facilitating increasing the coefficient of friction between sealing assembly  200  and recessed surface  132 . As a result, in such an embodiment, sealing assembly  200  may be substantially fixed in a sealing position, as described below. Alternatively, sealing assembly  200  and/or recessed surface  132  may not be coated with any lubricants. 
         [0031]    During operation of engine  10 , rotor disk  56  and rotor blades  48  rotate about longitudinal axis  11 . As rotor disk  56  rotates, a centrifugal force is generated and is induced to sealing assembly  200 . More specifically, the load induced by the centrifugal force increases as the rate of rotor disk rotation increases. As a result, rotor blades  48  have a force applied in a radially outward direction. In the exemplary embodiment, as the rotor disk increases in speed, a load is induced to dynamic plate  202  causing dynamic plate  202  to shift generally outward along recessed surface  132 . Specifically, in the exemplary embodiment, as a result of the movement, dynamic plate  202  contacts rope seal  206  such that static plate perimetrical flange  228  is received within dynamic plate channel  220 . More specifically, in the exemplary embodiment, the loading induced to sealing assembly  200  causes dynamic plate contoured edge  218  to contact rope seal  206  such that rope seal  206  is positioned against contoured edge  218  and channel outer surface  136 . Moreover, in the exemplary embodiment, as the load induced to sealing assembly  200  increases, the load enables dynamic plate contoured edge  218  to deform rope seal  206  such that rope seal  206  is separated from static plate outer surface  230 . As a result, the load causes dynamic plate  202  to shift generally outward along recessed surface  132  into a sealing position such that dynamic plate contoured edge  218  is positioned substantially between outer surface  230  of static plate  204  and rope seal  206 . As a result, contoured edge  218  facilitates expanding rope seal  206  generally outward from outer surface  230  such that rope seal  206  extends into gap  144  to facilitate sealing thereof. Moreover, in the exemplary embodiment, rope seal  206  is coupled to slot base  82  and axially outer surface  136  such that gap  144  is substantially sealed by rope seal  206 . 
         [0032]    In the exemplary embodiment, dynamic plate  202  facilitates expanding rope seal  206  such that rope seal facilitates sealing of gap  144 . As gap  144  is sealed, airflow through gap  144  is facilitated to be reduced. The reduction of leakage between upstream and downstream portions of rotor disk  56  facilitates increases engine performance and efficiency by reducing energy losses. 
         [0033]    Described herein is an exemplary sealing assembly that facilitates reducing and/or eliminating undesirable airflow between an upstream portion of a rotor disk and a downstream portion of the rotor disk. More specifically, the sealing assembly is coupled within each rotor blade coupled to a rotor disk of a gas turbine engine turbine assembly. The sealing assembly includes a rope seal that deforms during rotor operation to substantially seal a gap defined between the rotor blade and the rotor disk using centrifugal force. 
         [0034]    More specifically, the sealing assembly described herein facilitates improving gas turbine engine performance by reducing and/or preventing air leakage through and between stages of the rotor assembly. The reduction and/or prevention of leakage through the gap defined between the rotor blade and the rotor disk facilitates reducing the amount of sprayed aluminum that may be applied to a dovetail of the rotor blade and a slot base of the rotor disk. As a result, the exemplary embodiment effectively seals the gap and increases engine performance and efficiency while reducing the amount of spayed aluminum that may be applied to the dovetail and the rotor disk. 
         [0035]    While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.