Abstract:
An example method of assembling a particle damped gas turbine engine component according to an exemplary aspect of the present disclosure includes, among other things, holding damping media within a cavity of a gas turbine engine component using magnetic force.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to U.S. Provisional Application No. 61/939,788 filed on Feb. 14, 2014. 
     
    
     BACKGROUND 
       [0002]    This disclosure relates generally to structural guide vanes (SGVs) and, more particularly, to assembling SGVs having damping media. 
         [0003]    Gas turbine engines can use SGVs to control and guide the flow of air through the engine. SGVs can also support some engine components. In some example engines, SGVs are axially aft the fan of the aircraft engine. Other SGVs may be located in the compressor stages, the turbine stages, or other areas of the aircraft engines. 
         [0004]    SGVs and other airfoils can be prone to undesirable vibration during operation of the gas turbine engine. Particle damping has been used to suppress vibratory resonance experienced by SGVs. 
       SUMMARY 
       [0005]    A method of assembling a particle damped gas turbine engine component according to an exemplary aspect of the present disclosure includes, among other things, holding damping media within a cavity of a gas turbine engine component using magnetic force. 
         [0006]    In a further embodiment of the foregoing method, the method includes holding the damping media within the cavity of a structural guide vane. 
         [0007]    In a further embodiment of any of the foregoing methods, the method includes covering the cavity with a cover during the holding. 
         [0008]    In a further embodiment of any of the foregoing methods, the method includes bonding the cover to the cavity and removing the magnetic force. 
         [0009]    In a further embodiment of any of the foregoing methods, the method includes aligning magnetic fields to pass through the cavity and hold damping media within the cavity. 
         [0010]    In a further embodiment of any of the foregoing methods, the damping media is free to move within the cavity after the bonding. 
         [0011]    In a further embodiment of any of the foregoing methods, the damping media comprises shot peen media. 
         [0012]    In a further embodiment of any of the foregoing methods, an electromagnet selectively provides the magnetic force. 
         [0013]    In a further embodiment of any of the foregoing methods, the method includes aligning a first pole adjacent a first side wall of the cavity and an opposing, second pole of the magnet adjacent an opposing, second side wall of the cavity. 
         [0014]    A structural guide vane according to an exemplary aspect of the present disclosure includes, among other things, a radially outer platform, a radially inner platform, a vane body located between the radially outer platform and the radially inner platform, and a vane cover. The vane body includes one or more cavities. A vibration damping material filling the cavities is in direct contact with the vane body, the vane cover, or both. 
         [0015]    In further embodiment of the foregoing structural guide vane, the vibration damping material is shot peen media. 
         [0016]    In further embodiment of the foregoing structural guide vane, the cavities are formed on a side wall of the vane body. 
         [0017]    In a further embodiment of any of the foregoing structural guide vanes, the cavity is void of any container holding the vibration damping material. 
         [0018]    In a further embodiment of any of the foregoing structural guide vanes, the vane cover is adhesively bonded within a recessed area of the vane body. 
         [0019]    In a further embodiment of any of the foregoing structural guide vanes, the cavities are formed within the recessed area. 
         [0020]    In a further embodiment of any of the foregoing structural guide vanes, the vane body is aluminum. 
         [0021]    In a further embodiment of any of the foregoing structural guide vanes, wherein the vane cover is bonded to the vane body over the one or more cavities. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1  illustrates a schematic, cross-sectional view of an example gas turbine engine. 
           [0023]      FIG. 2  illustrates an exploded view of an example structural guide vane (SGV). 
           [0024]      FIG. 3  illustrates a highly schematic view of damping media aligning along lines of a magnetic field. 
           [0025]      FIG. 4  illustrates a shot peen media type of damping media aligning within a magnetic field. 
           [0026]      FIG. 5  illustrates a section view of the SGV of  FIG. 2  during assembly. 
           [0027]      FIG. 6  illustrates a section view of the SGV of  FIG. 2  when assembled. 
       
    
    
     DETAILED DESCRIPTION 
       [0028]      FIG. 1  schematically illustrates a gas turbine engine  20 . The gas turbine engine  20  is disclosed herein as a two-spool turbofan that generally incorporates a fan section  22 , a compressor section  24 , a combustor section  26  and a turbine section  28 . Alternative engines might include an augmentor section (not shown) among other systems or features. The fan section  22  drives air along a bypass flow path B in a bypass duct defined within a nacelle  15 , while the compressor section  24  drives air along a core flow path C for compression and communication into the combustor section  26  then expansion through the turbine section  28 . Although depicted as a two-spool turbofan gas turbine engine in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to use with two-spool turbofans as the teachings may be applied to other types of turbine engines including three-spool architectures. 
         [0029]    The exemplary engine  20  generally includes a low speed spool  30  and a high speed spool  32  mounted for rotation about an engine central longitudinal axis A relative to an engine static structure  36  via several bearing systems  38 . It should be understood that various bearing systems  38  at various locations may alternatively or additionally be provided, and the location of bearing systems  38  may be varied as appropriate to the application. 
         [0030]    The low speed spool  30  generally includes an inner shaft  40  that interconnects a fan  42 , a first (or low) pressure compressor  44  and a first (or low) pressure turbine  46 . The inner shaft  40  is connected to the fan  42  through a speed change mechanism, which in exemplary gas turbine engine  20  is illustrated as a geared architecture  48  to drive the fan  42  at a lower speed than the low speed spool  30 . The high speed spool  32  includes an outer shaft  50  that interconnects a second (or high) pressure compressor  52  and a second (or high) pressure turbine  54 . A combustor  56  is arranged in exemplary gas turbine engine  20  between the high pressure compressor  52  and the high pressure turbine  54 . A mid-turbine frame  57  of the engine static structure  36  is arranged generally between the high pressure turbine  54  and the low pressure turbine  46 . The mid-turbine frame  57  further supports bearing systems  38  in the turbine section  28 . The inner shaft  40  and the outer shaft  50  are concentric and rotate via bearing systems  38  about the engine central longitudinal axis A which is collinear with their longitudinal axes. 
         [0031]    The core airflow is compressed by the low pressure compressor  44  then the high pressure compressor  52 , mixed and burned with fuel in the combustor  56 , then expanded over the high pressure turbine  54  and low pressure turbine  46 . The mid-turbine frame  57  includes airfoils  59  which are in the core airflow path C. The turbines  46 ,  54  rotationally drive the respective low speed spool  30  and high speed spool  32  in response to the expansion. It will be appreciated that each of the positions of the fan section  22 , compressor section  24 , combustor section  26 , turbine section  28 , and geared architecture  48  may be varied. For example, geared architecture  48  may be located aft of combustor section  26  or even aft of turbine section  28 , and fan section  22  may be positioned forward or aft of the location of geared architecture  48 . 
         [0032]    The engine  20  in one example is a high-bypass geared aircraft engine. In a further example, the engine  20  bypass ratio is greater than about six (6), with an example embodiment being greater than about ten (10), the geared architecture  48  is an epicyclic gear train, such as a planetary gear system or other gear system, with a gear reduction ratio of greater than about 2.3 and the low pressure turbine  46  has a pressure ratio that is greater than about five. In one disclosed embodiment, the engine  20  bypass ratio is greater than about ten (10:1), the fan diameter is significantly larger than that of the low pressure compressor  44 , and the low pressure turbine  46  has a pressure ratio that is greater than about five 5:1. Low pressure turbine  46  pressure ratio is pressure measured prior to inlet of low pressure turbine  46  as related to the pressure at the outlet of the low pressure turbine  46  prior to an exhaust nozzle. The geared architecture  48  may be an epicycle gear train, such as a planetary gear system or other gear system, with a gear reduction ratio of greater than about 2.3:1. It should be understood, however, that the above parameters are only exemplary of one embodiment of a geared architecture engine and that the present invention is applicable to other gas turbine engines including direct drive turbofans. 
         [0033]    A significant amount of thrust is provided by the bypass flow B due to the high bypass ratio. The fan section  22  of the engine  20  is designed for a particular flight condition—typically cruise at about 0.8 Mach and about 35,000 feet. The flight condition of 0.8 Mach and 35,000 ft (10,668 meters), with the engine at its best fuel consumption—also known as “bucket cruise Thrust Specific Fuel Consumption (&#39;TSFC&#39;)”—is the industry standard parameter of lbm of fuel being burned divided by lbf of thrust the engine produces at that minimum point. “Low fan pressure ratio” is the pressure ratio across the fan blade alone, without a Fan Exit Guide Vane (“FEGV”) system. The low fan pressure ratio as disclosed herein according to one non-limiting embodiment is less than about 1.45. “Low corrected fan tip speed” is the actual fan tip speed in ft/sec divided by an industry standard temperature correction of [(Tram ° R)/(518.7 ° R)] 0.5 . The “Low corrected fan tip speed” as disclosed herein according to one non-limiting embodiment is less than about 1150 feet/second (350.5 meters/second). 
         [0034]    Referring now to  FIG. 2  with continuing reference to  FIG. 1 , at a position aft the fan  42 , the engine  20  includes a structural guide vane (SGV)  62 . The structural guide vanes  62  steers flow from the fan  42 . The SGV  62  also supports components of the engine  20  near the fan  42 . The SGV  62  is within an array of SGVs circumferentially distributed about the axis A. 
         [0035]    The SGV  62  includes a vane body  64  extending from a radially inner platform  68  to a radially outer platform  72 . In an installed position within the engine  20 , the radially inner platform  68  mounts to an inner hub of the engine  20 . The radially outer platform  72  mounts to an outer fan case of the engine  20 . 
         [0036]    The vane body  64  includes a plurality of cavities  76 . In the example embodiment, the cavities  76  are approximately rectangular in shape. The number and location of the cavities  76  may vary depending on the application. Cavities  76  may be formed on one or both sides of the SGV  62  depending on the circumferential depth of the SGV  62  and the depth of the cavities  76 . The cavities  76  could also be formed in the radially inner platform  68  or radially outer platform  72 . 
         [0037]    The cavities  76  are formed within a recessed area  80  of the vane body  64 . The recessed area  80  receives a vane body cover  84  when the SGV  62  is assembled. Vibration damping of the SGV  62  is provided by damping media placed within the cavity  76 . The vane cover  84  is adhesively secured to the recessed area  80  to hold the damping media within the cavities  76 . Notably, in this example, the damping media is not held within any container. The damping media is in direct contact with the vane body  64  and the vane body cover  84 . 
         [0038]    Placing damping media within the cavities  76 , and then placing the cover  84  within the recessed area  80  without disturbing the damping media, can be challenging. Example embodiments of this disclosure hold damping media within the cavities  76  during assembly using magnet fields to reduce these difficulties. 
         [0039]    Referring to  FIG. 3 , damping media  88  that is magnetic orients along magnetic field lines  90  when positioned near a magnet  92 . When oriented in this way, the damping media  88  has the arcing strands  94  following, generally, the paths of the magnetic field lines  90 . 
         [0040]    An example damping media  88  for placement within the cavities  76  is shot peen media  100  or bearing balls as shown in  FIG. 4 . Other example damping media includes sand, damping tape, ceramic particles, bearing balls, etc. 
         [0041]    The example shot peen media is stainless steel in this example. The shot peen media is cold formed and are magnetic. Shot peen media are not intrinsically ferromagnetic, but, in this example, by virtue of being subject to high amounts of cold work, sufficient grain alignment is achieved to behave like a ferromagnetic material. The shot peen media  100  is positioned within a magnetic field and are oriented in arcing strands. 
         [0042]    Referring now to  FIGS. 5 and 6 , magnets  104  are used to hold shot peen media  100  within the cavities  76  before the vane cover  84  is secured. The tendency of the shot peen media  100  to align in arcing strands along magnetic field lines facilitates holding the shot peen media  100  within the cavities  76 . 
         [0043]    In this example, when the shot peen media  100  are loaded into the cavities  76 , magnets  104  are positioned along a surface  108  of the vane body opposite the cavities  76 . The example magnets  104  are electromagnets that selectively induce magnetic fields  110  in response to a command from a controller C. The magnets  104  may be held within a fixture (not shown) that supports the vane body  64 . 
         [0044]    Generally, the example magnets  104  are aligned such that the magnetic fields  110  that enter the cavities  76  through a side of the floor  114  of the cavity  76  extend continuously to exit the cavity  76  through another side of the floor  114 . Also, the magnetic fields  110  that enter the cavity  76  through a side wall  118  of the cavity  76  extend continuously to exit the cavity  76  through the opposing side wall  122 . 
         [0045]    The magnetic force from the magnets  104  pulls the shot peen media  100  into the cavities  76 . The orientation of the flow fields  110  encourages the shot peen media  100  to orient themselves in strands within the cavities  76  along the magnetic fields  110 . 
         [0046]    Alignment along the flow fields  110  helps to ensure that the shot peen media  100  do not extend out of the cavities  76  to interfere with a bond line  126  between the cover  84  and the vane body  64 . The alignment of the magnetic fields  110  encourages strands of the shot peen media  100  that start within the cavities  76  to also stop within the cavities  76  rather than interfering with the bond line  126 . 
         [0047]    To encourage the magnetic fields  110  to align in this way, the magnets  104  have a first pole adjacent the side wall  118  and an opposing, second pole adjacent the side wall  122 . 
         [0048]    With no shot peen media  100  interfering with the bond line  126 , the cover  84  can then be adhesively secured within the recessed area  80  to the vane body  64  to hold the shot peen media  100  within the cavities  76 . The magnets  104  are removed or demagnetized after the cover  84  is secured. The shot peen media  100  are then held within the cavities  76  by the cover  84 . The shot peen media  100  directly contact the cover  84 , the floor  114 , the side walls  118 ,  122 . The shot peen media  100  are free to move within the cavities  76  without interference from any separate container. 
         [0049]    Vibration damping of the SGV  62  can be influenced by the amount of shot peen media  100  within the cavities  76 . Notably, the example method enables filling the cavities  76  with the shot peen media  100  without requiring a separate container within the cavities  76  holding the shot peen media  100 . This maximizes damping area within a given area of the cavities  76 . If containers were required, the container would occupy at least some of the space of the cavities  76 . 
         [0050]    In addition to the selection and placement of the damping material, which is the shot peen media  100  in this example, various types of materials may be utilized to form the vane body  64  and the cover  84 . In some examples, these components are formed of the same material, such as aluminum or organic matrix composite. In other examples, the vane body  64  and the cover  84  are formed of different materials to vary performance parameters of the SGV  62 , such as weight, stiffness, or both. 
         [0051]    The example damping is described with reference to the SGV  62 . Similar techniques of magnetic retention of damping media could be used in connection with other components, such as other airfoil components of the engine  20  ( FIG. 1 ) like vanes. 
         [0052]    Although the different non-limiting embodiments are illustrated as having specific components, the embodiments of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments. 
         [0053]    Although embodiments of this invention have been disclosed, a worker of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.