Abstract:
A bladed rotor includes a blade lock mountable to a rotor hub adjacent to a multiple of blade slots. The blade lock includes at least one interface feature adjacent to a first of the multiple of blade slots. A first rotor blade includes a blade feature which interfaces with the interface feature to permit the first rotor blade to be axially mounted within the first of the multiple of blade slots but not within a remainder of the multiple of blade slots.

Description:
BACKGROUND 
       [0001]    The present disclosure relates to an axial retention system for a bladed rotor, particularly a fan rotor of a gas turbine engine. 
         [0002]    A fan rotor of the type used in an aircraft gas turbine engine includes a hub which rotates about a rotational axis and an array of blades which extend radially from the hub. The hub includes a series of circumferentially distributed peripheral slots. Each slot extends in a predominantly axial direction. Each slot is typically open at either a forward section of the hub, an aft section of the hub, or both to facilitate axial installation and removal of the blades. An axial retention system prevents the installed blades from migrating axially out of the slots. 
       SUMMARY 
       [0003]    A bladed rotor according to an exemplary aspect of the present disclosure includes a blade lock mountable to a rotor hub adjacent to a multiple of blade slots. The blade lock includes at least one interface feature adjacent to a first of the multiple of blade slots. A first rotor blade includes a blade feature which interfaces with the interface feature to permit the first rotor blade to be axially mounted within the first of the multiple of blade slots but not within a remainder of the multiple of blade slots. 
         [0004]    A bladed rotor according to an exemplary aspect of the present disclosure include a rotor hub which defines a multiple of first blade slots and a multiple of second blade slots. A blade lock is mountable to the rotor hub adjacent to the multiple of first and second blade slots, the blade lock includes a multiple of first interface features each adjacent to one of the multiple of first blade slots. A multiple of first rotor blades with a blade feature which interfaces with the interface feature to permit the multiple of first rotor blades to be axially mounted within the multiple of first blade slots but not within the multiple of second blade slots. 
         [0005]    A method of assembling a bladed rotor according to an exemplary aspect of the present disclosure includes permitting a first rotor blade to be axially mounted within a first of a multiple of blade slots by a blade lock but not within a remainder of the multiple of blade slots by the blade lock. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiment. The drawings that accompany the detailed description can be briefly described as follows: 
           [0007]      FIG. 1  is a schematic cross-section of a gas turbine engine; 
           [0008]      FIG. 2  is an enlarged perspective partial sectional view of a fan section; 
           [0009]      FIG. 3  is an enlarged perspective view of a rotor hub with a blade lock and one blade root partially installed; 
           [0010]      FIG. 4  is a rear perspective view of a rotor hub with a blade lock and one blade root installed; 
           [0011]      FIG. 5  is a rear enlarged perspective view of a rotor hub showing a blade slot and blade lock according to one non-limiting embodiment with a blade portion in a partially installed position; 
           [0012]      FIG. 6  is a rear enlarged perspective view of a rotor hub showing a blade slot and blade lock with blade portions in an installed position; and 
           [0013]      FIG. 7  is a rear enlarged perspective view of a rotor hub showing a blade slot, blade lock, and blade portions according to another non-limiting embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]      FIG. 1  schematically illustrates a gas turbine engine  20 . The gas turbine engine  20  is disclosed herein as a 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 flowpath while the compressor section  24  drives air along a core flowpath for compression and communication into the combustor section  26  then expansion through the turbine section  28 . Although depicted as a 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 turbofans as the teachings may be applied to other types of turbine engines. 
         [0015]    The 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. 
         [0016]    The low speed spool  30  generally includes an inner shaft  40  that interconnects a fan  42 , a low pressure compressor  44  and a low pressure turbine  46 . The inner shaft  40  is connected to the fan  42  through 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 high pressure compressor  52  and high pressure turbine  54 . A combustor  56  is arranged between the high pressure compressor  52  and the high pressure turbine  54 . The inner shaft  40  and the outer shaft  50  are concentric and rotate about the engine central longitudinal axis A which is collinear with their longitudinal axes. 
         [0017]    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 turbines  54 ,  46  rotationally drive the respective low speed spool  30  and high speed spool  32  in response to the expansion. 
         [0018]    With reference to  FIG. 2 , the fan  42  includes a plurality of circumferentially spaced fan blades  60  which may be manufactured of a high-strength, low weight material such as an aluminum alloy, titanium alloy, composite, or combinations thereof. It should be understood that although a single fan stage is illustrated and described in the disclosed embodiment, additional stages as well as other bladed rotor with other blades that are received with an axial interface inclusive of fan blades, compressor blades and turbine blades will also benefit herefrom. 
         [0019]    Each fan blade  60  generally includes an innermost root portion  62 , an intermediate platform portion  64 , and an outermost airfoil portion  66 . The root portion  60  may define an attachment such as an inverted fir-tree, bulb, or dovetail so the fan blade  60  is slidably received in a complimentary configured blade slot  68  in a fan rotor hub  70  to provide a bladed rotor  72  about axis A. The illustrated blade slots, when viewed radially toward the axis A, have a curved profile. Alternatively, the slots may be linear slots having a linear centerline oriented parallel or oblique to the rotational axis. Each slot  68  includes a forward section  68 F and an aft section  68 A to accommodate installation and removal of the fan blades  60  in a generally axial direction ( FIG. 3 ). As defined herein, the term “axial” refers not only to a direction strictly parallel to the rotational axis but also to directions somewhat non-parallel to the axis, such as the slotwise direction defined by a curved or linear slot. 
         [0020]    Such bladed rotors sometimes require two or more different blades  60 A,  60 B mounted to the same rotor hub  70  to facilitate, for example, vibration tuning, flutter margin control and/or adjustment of other parameters. To achieve the desired parameters it is imperative that the specific blade  60 A,  60 B always be mounted at their proper circumferential positions in a mistake-proof manner. 
         [0021]    With reference to  FIG. 4 , the bladed rotor  72  includes a multiple of lock attachments  74  such as annular hooks which support a blade lock  76  such as a snap ring. The blade lock  76  is received within the multiple of lock attachments  74  along an aft face  70 A of the rotor hub  70  to interface with each blade slot  68 . The blade lock  76  may be circumferentially continuous except for a split  80  that enables a technician to deflect the blade lock  76  to mount within the multiple of lock attachments  74  as generally known. It should be understood that the bladed rotor  72  is described somewhat generically and that additional hub components such as a bayonet ring, a retainer ring and others may also be provided but need not be described in detail herein. 
         [0022]    With reference to  FIG. 5 , the blade lock  76  includes at least one interface feature  82  at specific circumferential features with respect to a blade slot  68  to interact with a blade feature  84  and assure that only the desired particular type of blade  60 A may be mounted within that associated blade slot  68 . That is, the interface feature  82  is circumferentially arranged to align with each blade slot  68  to mount only specific desired blade types such as blade  60 A ( FIG. 6 ). The remainder of the blade slots  68  will receive, for example, blades  60 B. 
         [0023]    The interface feature  82 A ( FIG. 7 ) and the blade feature  84 A are complementary features such as a slot in the blade lock  76  which receives a key which extends from the root portion  62  of blade  60 A. The key may be positioned to extend from an aft axial end section  62 A of the root portion  62 . 
         [0024]    Even though each of the blade slots  68  are equivalent, the disclosed interface permits only blade  60 A to fit into the appropriate blade slot  68  adjacent to the interface feature  82  and prevents the blade  60 B from being mounted into a blade slot  68  which is not adjacent to that interface feature. For example, if blade  60 A is installed in a blade slot  68  which is intended for blade  60 B, the key will not fit the slot, and the blade  60 A cannot be fully installed in the axial direction to thereby prevent installation of a front blade lock (not shown) which would halt installation until all blades  60 A,  60 B are positioned at their correct locations. A mistake-proof interface is thereby provided. 
         [0025]    It should be understood that other features such as a slot in the blade and a key in the blade lock  74  may alternatively be provided to mistake-proof the installation. 
         [0026]    In yet another non-limiting embodiment, the interface feature  82 A,  82 B and the blade feature  84 A,  84 B may be independent and mutually exclusive so that only the single proper blade  60 A,  60 B may be located in the proper blade slot  68  ( FIG. 7 ). It should be understood that various geometric shapes such as arcuate, rectilinear, triangular, and others may define the interface features  82 A,  82 B and the blade features  84 A,  84 B to facilitate a mistake-proof installation. 
         [0027]    It should be understood that relative positional terms such as “forward,” “aft,” “upper,” “lower,” “above,” “below,” and the like are with reference to the normal operational attitude of the vehicle and should not be considered otherwise limiting. 
         [0028]    It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom. 
         [0029]    Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present disclosure. 
         [0030]    The foregoing description is exemplary rather than defined by the limitations within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be understood that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content.