Abstract:
In accordance with one aspect of the disclosure, a lubricant application device for providing lubricant to an airfoil of a gas turbine engine is disclosed. The device may include a container for holding a lubricant, a fluid outlet in fluid communication with the container, a discharge mechanism controlling a flow of the lubricant from the container to the fluid outlet, and an extension tube in fluid communication with the fluid outlet. When the discharge mechanism is activated the lubricant may flow out of the container and through the extension tube. The extension tube may be dimensioned to fit between an airfoil root and rotor cavity of a gas turbine engine.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a US National Stage under 35 USC §371 of International Patent Application No. PCT/US13/76011 filed on Dec. 18, 2013, and claims priority under 35 USC §119(e) to U.S. Provisional Patent Application Ser. No. 61/799,534 filed on Mar. 15, 2013. 
     
    
     FIELD OF THE DISCLOSURE 
       [0002]    The present disclosure generally relates to gas turbine engines, and more specifically to lubrication of fan blade roots for a gas turbine engine. 
       BACKGROUND OF THE DISCLOSURE 
       [0003]    Gas turbine engines generally have a plurality of axially aligned components including a fan, a compressor section, a combustor, and a turbine section. The fan, positioned at a forward end of the engine, rotates to draw in and pressurize ambient air. The pressurized air flows to the compressor section, as a core flow, where the air is compressed further and then flows to the combustor. At the combustor, the compressed air is mixed with fuel and combusted to form an exhaust. The exhaust expands from the combustor through the turbine section, causing rotors of the turbine section to rotate, and then flows out of the engine at an aft end of the engine. The rotation of the turbine rotors drive the rotation of the fan and rotors of the compressor section by way of a shaft, or a plurality of concentrically mounted shafts in the case of a multi-spool engine. 
         [0004]    The fan typically includes a rotor disk and a plurality of blades extending radially outward from the rotor disk. Each of the blades typically has a root that is positioned within a root cavity of the rotor disk that prevents the blades from disengaging from the rotor disk during operation of the fan. However, centrifugal forces on the blades cause the root to chafe against the rotor disk. This chafing is typically mitigated by applying a lubricant to the affected surfaces. To accomplish this using prior art methods, each blade must be disengaged from the rotor disk, the lubricant can then be applied, and then the blades can be re-assembled with the rotor disk. Once the blades are reengaged with the rotor disk the fan must be tested which entails running the engine up to operational speeds to determine if the blades were reinstalled correctly. This may require the engine and associated aircraft to be moved due to space or noise constraints. If the blades were incorrectly installed then the fan may need to be disassembled and then reassembled in the correct manner. This process is time consuming and exposes the blades and rotor disk to potential damage due to incorrect reassembly or mis-handling of the engine components. Therefore, a new method for lubricating the root and root cavity of the fan without disassembling the fan is needed. 
       SUMMARY OF THE DISCLOSURE 
       [0005]    In accordance with one aspect of the disclosure, a lubricant application device for providing lubricant to an airfoil of a gas turbine engine is disclosed. The device may include a container for holding a lubricant, a fluid outlet in fluid communication with the container, a discharge mechanism controlling a flow of the lubricant from the container to the fluid outlet, and an extension tube in fluid communication with the fluid outlet. When the discharge mechanism is activated the lubricant may flow out of the container and through the extension tube. The extension tube may be dimensioned to fit between an airfoil root and rotor cavity of a gas turbine engine. 
         [0006]    In a refinement, the lubricant application device may be a hand-held spray gun. 
         [0007]    In another refinement, a distal tip of the extension tube may be formed to an angle less than one-hundred eighty degrees. 
         [0008]    In a further refinement, the distal tip of the extension tube may be formed to an angle of about forty-five degrees. 
         [0009]    In yet another refinement, the extension tube may be constructed from a plastic material. 
         [0010]    In accordance with another aspect of the present disclosure, a method of applying a lubricant to a rotor of a gas turbine engine is disclosed. The method may include a step of providing a lubricant application device having a container for holding the lubricant, a fluid outlet in fluid communication with the container, a discharge mechanism controlling a flow of lubricant from the container to the fluid outlet, and an extension tube in fluid communication with the fluid outlet. The method may further include positioning the extension tube proximate the rotor and activating the discharge mechanism to release the lubricant from the container and onto the rotor. 
         [0011]    In a refinement, the method may further include deactivating the discharge mechanism, removing the extension tube from proximate the rotor, and returning the rotor to active use. 
         [0012]    In a further refinement, the method may further include repeating the steps of positioning the extension tube, activating the discharge mechanism, deactivating the discharge mechanism, and removing the extension tube a plurality of times before returning the rotor to active use. 
         [0013]    In another refinement, the positioning of the extension tube may include inserting the extension tube into a cavity formed in a rotor disk to accept a blade of the rotor. 
         [0014]    In a further refinement, inserting the extension tube into the cavity may include bending the extension tube around the shape of at least one of the blade and rotor disk. 
         [0015]    In another further refinement, the method may further include releasing lubricant onto a pressure surface of a root of the blade. 
         [0016]    In yet another refinement, activating the discharge mechanism may include depressing a trigger. 
         [0017]    In a further refinement, deactivating the discharge mechanism may include releasing a trigger. 
         [0018]    In accordance with yet another aspect of the present disclosure, a method of applying a lubricant to a fully assembled rotor of a gas turbine engine is disclosed. The method may include providing a lubricant application device having a container for holding the lubricant, a fluid outlet in fluid communication with the container, a discharge mechanism controlling the flow of lubricant from the container to the fluid outlet, and an extension tube in fluid communication with the fluid outlet. The method may further include inserting the extension tube into a root cavity formed in a rotor disk of the rotor to accept a root of a blade of the rotor and activating the discharge mechanism to release the lubricant from the container and onto the rotor. 
         [0019]    In a refinement, the method may further include deactivating the discharge mechanism, removing the extension tube from the root cavity, and returning the rotor to active use. 
         [0020]    In a further refinement, the method may further include repeating the steps of inserting the extension tube, activating the discharge mechanism, deactivating the discharge mechanism, and removing the extension tube a plurality of times before returning the rotor to active use. 
         [0021]    In another refinement, the method may further include releasing the lubricant onto a pressure surface of the root. 
         [0022]    In a further refinement, the method may further include providing the extension tube with a length greater than an axial length of the pressure surface of the root. 
         [0023]    In yet another refinement, the method may further include providing the rotor as a fan of the gas turbine engine and not removing the fan from the gas turbine engine to apply the lubricant. 
         [0024]    In still another refinement, the step of inserting the extension tube into the root cavity may involve bending the extension tube to reach a pressure surface of the root. 
         [0025]    These and other aspects and features of the present disclosure will be better understood in light of the following detailed description when read in light of the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIG. 1  is a partial cross-sectional view of a gas turbine engine. 
           [0027]      FIG. 2  is a cross-sectional view of a root of a blade engaged with a rotor disk. 
           [0028]      FIG. 3  is a perspective view of a root of a blade. 
           [0029]      FIG. 4  is a perspective view of a fragment of a rotor disk detailing a plurality of root cavities. 
           [0030]      FIG. 5  is a schematic view of a lubrication application device constructed in accordance with an embodiment of the present disclosure. 
           [0031]      FIG. 6  is a perspective view of a lubrication application method performed in accordance with an embodiment of the present disclosure. 
       
    
    
       [0032]    It should be understood that the drawings are not necessarily to scale and that the disclosed embodiments are sometimes illustrated diagrammatically and in partial views. In certain instances, details which are not necessary for an understanding of this disclosure or which render other details difficult to perceive may have been omitted. It should be understood, of course, that this disclosure is not limited to the particular embodiments illustrated herein. 
       DETAILED DESCRIPTION 
       [0033]    Referring now to the drawings, and with specific reference to  FIG. 1 , a gas turbine engine is illustrated and generally indicated by reference numeral  20 . As can be seen, the engine  20  may include a plurality of components axially aligned along a engine axis  22 . At a forward end of the engine  20  a fan  24  rotates to draw in and pressurize ambient air. This air flows downstream through the engine  20  to a compressor section  26  where it is compressed. From the compressor section  26 , the compressed air flows further downstream to a combustor  28  where the air is mixed with a fuel and combusted to generate heat and form an exhaust. The exhaust expands even further downstream through a turbine section  30  and exits the engine  20  at an aft end. As the exhaust expands, rotors of the turbine section  30  are rotated. This rotational motion is communicated to the fan  24  and rotors of the compressor section  26  via an engine shaft  32 , or plurality of engine shafts  32  in the case of a dual-spool engine  20  as shown. 
         [0034]    The fan  24  may include a rotor disk  36  and a plurality of blades  38  extending radially outward from the rotor disk  36 . As can be seen in  FIG. 2 , each of the blades  38  may include a root  40  and the rotor disk  36  may include a plurality of root cavities  42 . Each cavity  42  may be configured to receive and retain the root  40  of one of the blades  38 . During operation of the engine  20 , this configuration prevents the blades  38  from disengaging from the rotor disk  36 . However, the rotational motion of the rotor disk  36  creates centrifugal forces on the blades  38  that pull the blades  38  radially outward away from the engine axis  22 , causing a pressure surface  44  of the root  40 , best seen in  FIG. 3 , to chafe against a retention surface  46  of the rotor disk  36 , best seen in  FIG. 4 . The contact between the surfaces  44 ,  46  prevent the blade  38  from disengaging from the rotor disk  36 . When the engine transitions between high and low power operations, the blade  38  may transition between a tight position and a loose position. The blade may get caught in the tight position, which can cause undesirable vibrations in the fan  24 . Therefore, a lubricant  48  is needed to reduce the chafing between these surfaces  44 ,  46  and allow the blades  38  to move easier between the tight and loose positions. The prior art requires the fan  24  to be dismantled before the lubricant  48  may be applied to act on the root  40  and root cavity  42 . However, this method is undesirable and a new device and method is detailed below. It is in this regard that the present disclosure greatly improves upon the prior art. 
         [0035]    More specifically, in order to provide the lubricant  48  to the root  40  and root cavity  42  without dismantling the fan  24  a lubricant application device  50  is used. This device  50  may include a container  52  to hold the lubricant  48 , a fluid outlet  54  in fluid communication with the container  52 , a discharge mechanism  56  that controls a flow of the lubricant  48  from the container  52  to the fluid outlet  54 , and an extension tube  58  in fluid communication with the fluid outlet  54 . One example of a lubricant application device  50  may be a hand-held spray gun such as the one illustrated in  FIG. 5 . However, the spray gun illustrated herein should not be considered limiting in any way as it is provided for description purposes only. 
         [0036]    When the fan  24  is not in operation, the surfaces  44  and  46  are not forced together as strongly as during operation of the engine  20  and allows the lubricant  48  to move between the surfaces  44 ,  46 . To provide this lubricant  48 , the extension tube  58  may be inserted into the root cavity  42 . When discharged into the cavity  42 , the lubricant  48  may be acted upon by gravity causing the lubricant  48  to flow to the surfaces  46 ,  48 . In an alternative method, the lubricant  48  may be released into an outer cavity  59  formed between the blade  38  and the rotor disk  36 . The extension tube  58  may be used to discharge the lubricant  48  along an axial length of outer cavity  59  and gravity may act on this lubricant  48  to cause it to flow to the surfaces  46 ,  48 . To better assist in the application of the lubricant  48 , the extension tube  58  may have a length greater than a length of the surfaces  44 ,  46  in order to provide coverage of an entire axial length of the surfaces  44 ,  46  when inserting the extension tube  58  from only one side of the fan  24 . In one embodiment, the length of the extension tube  58  is about sixteen inches where the lengths of the surfaces are about twelve inches. However, other lengths are possible, and this is only one exemplary embodiment. 
         [0037]    The extension tube  58  may further include a distal tip  60  that discharges the lubricant  48 . This tip  60  may be bent at an angle α to better direct the lubricant  48  onto the surfaces  44 ,  46  when the extension tube  58  is inserted into the root cavity  42 . In one embodiment, the angle α is about forty-five degrees. However, the presented angle is only one exemplary embodiment and other angles are also possible. The extension tube  58  may be flexible to allow the extension tube  58  to bend around contours of the root  40  and root cavity  42 . 
         [0038]    The extension tube  58  may be constructed of a plastic to provide a sturdy, flexible structure that retains its straight shape, but may be bent around an object, such as the rotor disk  36  to reach a desired location such as the surfaces  44 ,  46 . A rubber tube may allow the tube to bend as needed, however the rubber tube may not be able to retain the sturdy shape needed to insert the tube into the root cavity  42 . A metal tube may allow the tube to have the desired sturdy shape, but metal typically does not bend well and once bent typically does not return to its original shape and, therefore, may not be reusable. Also, the plastic extension tube  58  may reduce any potential damage to the fan  24 , due to contact between the extension tube  58  and the fan  24 , as opposed to a metal tube. However, any desired material may be used to construct the extension tube  58  and plastic is only one example thereof. 
       INDUSTRIAL APPLICABILITY 
       [0039]    From the foregoing, it can be seen that the technology disclosed herein has industrial applicability in a variety of settings such as, but not limited to providing a lubricant to chafing surfaces between a fan blade root and fan rotor disk. The lubricant application device may accomplish this task by including an extension tube that can be inserted between into the root cavity of a rotor disk while a blade is still engaged with the rotor disk. This may allow the fan to be lubricated without the need to disassemble the fan, which may reduce the time necessary for lubrication, reduce potential damage to the fan and engine due to dropped materials or engine components, and prevent mis-assembly of the fan once the lubrication has been completed. 
         [0040]    While the present disclosure has been made in reference to a gas turbine engine and an aircraft, and specifically to a fan for a gas turbine engine, one skilled in the art will understand that the teachings herein can be used in other applications as well such as, but not limited to, providing a lubricant to other airfoils of a gas turbine engine or other hard-to-reach surfaces that require lubrication. It is therefore intended that the scope of the invention not be limited by the embodiments presented herein as the best mode for carrying out the invention, but that the invention include all equivalents falling within the spirit and scope of the appended claims as well.