Patent Publication Number: US-10787921-B2

Title: High pressure turbine rear side plate

Description:
FIELD 
     The present disclosure relates to gas turbine engines and, more particularly, to side plates used on turbine rotor assemblies of gas turbine engines. 
     BACKGROUND 
     Gas turbine engines, such as those used to power modern commercial and military aircraft, include a fan section to propel the aircraft, a compressor section to pressurize a supply of air from the fan section, a combustor section to burn a hydrocarbon fuel in the presence of the pressurized air, and a turbine section to extract energy from the resultant combustion gases in order to power the compressor and fan sections. 
     Turbine sections within gas turbine engines commonly include one or more rotors, each having a plurality of blades extending radially outward of the rotors relative to a central longitudinal or rotational axis about which each of the rotors rotates. In some gas turbine engines, one or more cover plates are secured to the rotors within the turbine sections. The cover plates may assist in creating cooling volumes for the faces and other portions of the rotors and plenums for cooling air to flow into the root sections and then into the interiors of the blades comprising one or more of the pluralities of blades. The cover plates may also assist in securing the root sections of the blades within the radially outer portions or rims of the rotors. 
     SUMMARY 
     A cover plate for a rotor assembly is disclosed. In various embodiments, the cover plate includes an annular member having a radially inner portion and a radially outer portion with respect to a longitudinal axis, the radially inner portion including an aft face and an angled forward face, the angled forward face defining a forward face angle with respect to a cylindrical plane that is coaxial with the longitudinal axis, the face angle having a value that is greater than or equal to fifty degrees; a first tab and a second tab disposed proximate the radially inner portion of the annular member; and a slot disposed between the first tab and the second tab. 
     In various embodiments, the radially inner portion further includes a first forward face disposed radially inward of the angled forward face. In various embodiments, the radially inner portion further includes a second forward face disposed radially outward of the angled forward face. In various embodiments, the first forward face has a first forward face normal directed substantially parallel to the longitudinal axis. In various embodiments, the second forward face has a second forward face normal directed substantially parallel to the longitudinal axis. 
     In various embodiments, the cover plate includes a web face extending radially from proximate the radially inner portion to proximate the radially outer portion and the aft face is offset in a forward axial direction from the web face by an offset distance. In various embodiments, the aft face is configured for engagement with an annular arm of a rotor disk. In various embodiments, the aft face includes an aft face normal that is directed substantially parallel to the longitudinal axis. 
     In various embodiments, the slot includes a slot face that intersects the angled forward face along a forward intersection line. In various embodiments, the forward intersection line includes a sharp transition portion extending from a first slot end to a second slot end. In various embodiments, the slot face intersects the aft face along an aft intersection line and the aft intersection line includes a chamfered portion extending from the first slot end to the second slot end. In various embodiments, the slot face intersects the aft face along an aft intersection line and the aft intersection line includes a radiused portion extending from the first slot end to the second slot end. In various embodiments, the forward face angle is within a range from about fifty degrees to about eighty degrees. 
     A rotor assembly for a turbine section of a gas turbine engine is disclosed. In various embodiments, the rotor assembly includes a rotor disk configured to rotate about a longitudinal axis; a plurality of blades extending radially outward of the rotor disk from a rim portion of the rotor disk; and a cover plate configured for attachment to the rotor disk. In various embodiments, the cover plate includes an annular member having a radially inner portion and a radially outer portion with respect to the longitudinal axis, the radially inner portion including an aft face and an angled forward face, the angled forward face defining a forward face angle with respect to a cylindrical plane that is coaxial with the longitudinal axis, the face angle having a value that is greater than or equal to fifty degrees; a first tab and a second tab disposed proximate the radially inner portion of the annular member; and a slot disposed between the first tab and the second tab. 
     In various embodiments, the radially inner portion further includes a first forward face disposed radially inward of the angled forward face and a second forward face disposed radially outward of the angled forward face. In various embodiments, the first forward face has a first forward face normal directed substantially parallel to the longitudinal axis and the second forward face has a second forward face normal directed substantially parallel to the longitudinal axis. In various embodiments, the cover plate further includes a web face extending radially from proximate the radially inner portion to proximate the radially outer portion and the aft face is offset in a forward axial direction from the web face by an offset distance. 
     In various embodiments, the slot includes a slot face that intersects the angled forward face along a forward intersection line, the forward intersection line including a sharp transition portion extending from a first slot end to a second slot end, and the slot face intersects the aft face along an aft intersection line, the aft intersection line including one of a chamfered portion or a radiused portion extending from the first slot end to the second slot end. In various embodiments, the forward face angle is within a range from about fifty degrees to about eighty degrees. 
     A high pressure turbine section of a gas turbine engine is disclosed. In various embodiments, the high pressure turbine section includes an upstream rotor assembly; a downstream rotor assembly; a stator assembly disposed intermediate the downstream rotor assembly and the upstream rotor assembly; and a cover plate configured for attachment to a rear face of the downstream rotor assembly. In various embodiments, the cover plate includes an annular member having a radially inner portion and a radially outer portion with respect to a longitudinal axis, the radially inner portion including an aft face and an angled forward face, the angled forward face defining a forward face angle with respect to a cylindrical plane that is coaxial with the longitudinal axis, the face angle having a value that is greater than or equal to fifty degrees; a first tab and a second tab disposed proximate the radially inner portion of the annular member; and a slot disposed between the first tab and the second tab, the slot including a slot face that intersects the angled forward face along a forward intersection line, the forward intersection line including a sharp transition portion extending from a first slot end to a second slot end and the slot face intersecting the aft face along an aft intersection line, the aft intersection line including one of a chamfered portion or a radiused portion extending from the first slot end to the second slot end. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present disclosure, however, may best be obtained by referring to the following detailed description and claims in connection with the following drawings. While the drawings illustrate various embodiments employing the principles described herein, the drawings do not limit the scope of the claims. 
         FIG. 1A  is a schematic view of a gas turbine engine, in accordance with various embodiments; 
         FIG. 1B  is a schematic side view of a rotor and vane assembly of a turbine section of a gas turbine engine, in accordance with various embodiments; 
         FIG. 2A  is a schematic axial view of a cover plate used within a gas turbine engine, in accordance with various embodiments; 
         FIGS. 2B, 2C and 2D  are schematic cross sectional views of the cover plate illustrated in  FIG. 2A , in accordance with various embodiments; and 
         FIGS. 3A and 3B  are schematic perspective views of a slot within a cover plate, in accordance with various embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description of various embodiments herein makes reference to the accompanying drawings, which show various embodiments by way of illustration. While these various embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized and that changes may be made without departing from the scope of the disclosure. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected, or the like may include permanent, removable, temporary, partial, full or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact. It should also be understood that unless specifically stated otherwise, references to “a,” “an” or “the” may include one or more than one and that reference to an item in the singular may also include the item in the plural. Further, all ranges may include upper and lower values and all ranges and ratio limits disclosed herein may be combined. 
     Referring now to the drawings,  FIG. 1A  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 . 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 or primary flow path C for compression and communication into the combustor section  26  and 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. 
     The gas turbine 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 at various locations may alternatively or additionally be provided and the location of the several bearing systems  38  may be varied as appropriate to the application. 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 speed change mechanism, which in this gas turbine engine  20  is illustrated as a fan drive gear system  48  configured 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 a high pressure turbine  54 . A combustor  56  is arranged in the 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  and may include airfoils  59  in the core flow path C for guiding the flow into the low pressure turbine  46 . The mid-turbine frame  57  further supports the several bearing systems  38  in the turbine section  28 . The inner shaft  40  and the outer shaft  50  are concentric and rotate via the several bearing systems  38  about the engine central longitudinal axis A, which is collinear with longitudinal axes of the inner shaft  40  and the outer shaft  50 . 
     The air in the core flow path C is compressed by the low pressure compressor  44  and then the high pressure compressor  52 , mixed and burned with fuel in the combustor  56 , and then expanded over the high pressure turbine  54  and low pressure turbine  46 . The low pressure turbine  46  and the high pressure turbine  54  rotationally drive the respective low speed spool  30  and the high speed spool  32  in response to the expansion. It will be appreciated that each of the positions of the fan section  22 , the compressor section  24 , the combustor section  26 , the turbine section  28 , and the fan drive gear system  48  may be varied. For example, the fan drive gear system  48  may be located aft of the combustor section  26  or even aft of the turbine section  28 , and the fan section  22  may be positioned forward or aft of the location of the fan drive gear system  48 . 
     Referring now to  FIG. 1B , selected portions of a turbine section  100  of a gas turbine engine, such as, for example, the high pressure turbine  54  within the turbine section  28  described above with reference to  FIG. 1A , are illustrated. The turbine section  100  includes alternating rows of rotor assemblies  102  and stator assemblies  104 . Each of the rotor assemblies  102  carries one or more rotor blades  106  for rotation about a central longitudinal axis A. Each of the rotor blades  106  includes a rotor platform  108  and an airfoil  110  extending in a radial direction R from the rotor platform  108  to a rotor tip  112 . The airfoil  110  generally extends in a chord-wise direction X between a leading edge  114  and a trailing edge  116 . A root section  118  of each of the rotor blades  106  is mounted to a rotor disk  103 , which may be either an upstream rotor disk  105  or a downstream rotor disk  107 . A blade outer air seal (BOAS)  120  is disposed radially outward of the rotor tip  112  of the airfoil  110 . The BOAS  120  includes a platform  121  that provides a seal to prevent hot gases from leaking outside the core airflow path C (see  FIG. 1 ). 
     Each of the stator assemblies  104  includes one or more vanes  122  positioned along the central longitudinal axis A and adjacent to one or more rotor blades  106 . Each of the vanes  122  includes an airfoil  124  extending between an inner vane platform  126  and an outer vane platform  128 . The stator assemblies  104  are connected to an engine casing structure  130 . The BOAS  120  and the stator assemblies  104  may be disposed radially inward of the engine casing structure  130 . In various embodiments, one or both of the BOAS  120  and the stator assemblies  104  may include full annular platforms or they may be segmented and include feather seals between segments to help prevent leakage of cooling fluid between the segments. In various embodiments, one or more of the vanes  122  may be configured to rotate about an axis extending between the inner vane platform  126  and the outer vane platform  128 . 
     Still referring to  FIG. 1B , the turbine section  100  may also include a first front cover plate  140 , a first rear cover plate  142 , a second front cover plate  144  and a second rear cover plate  150 . In various embodiments, the cover plates operate as air seals for air flow into and out of the rotor assemblies  102 . In various embodiments, the cover plates may also serve to maintain the one or more rotor blades  106  within each rotor disk  103  corresponding to each of the rotor assemblies  102 . In various embodiments, an annular seal  146  interfaces with a first knife edge seal  147  and a second knife edge seal  148 . In various embodiments, the first knife edge seal  147  may be integral with the first rear cover plate  142  and the second knife edge seal  148  may be integral with the second front cover plate  144 , respectively. 
     In various embodiments, the upstream rotor disk  105  includes a first front annular arm  141  and a first rear annular arm  143 , both first annular arms extending generally in a radially outward direction from points of attachment to respective forward and aft faces of the upstream rotor disk  105  and configured to engage radially inner portions of the first front cover plate  140  and the first rear cover plate  142 . Similarly, in various embodiments, the downstream rotor disk  107  includes a second front annular arm  145  and a second rear annular arm  149 , both second annular arms extending generally in a radially outward direction from points of attachment to respective forward and aft faces of the downstream rotor disk  107  and configured to engage radially inner portions of the second front cover plate  144  and the second rear cover plate  150 . 
     Referring now to  FIGS. 2A, 2B, 2C and 2D , a cover plate  250 , such as, for example, the second rear cover plate  150  described above with reference to  FIG. 1B , is illustrated, in accordance with various embodiments.  FIGS. 2B and 2C  are cross sectional views of the cover plate  250 , as indicated in  FIG. 2A .  FIG. 2D  is an enlarged cross sectional view of a portion of the cover plate  250 , as indicated in  FIG. 2B . In various embodiments, the cover plate  250  (or cover seal) comprises an annular member  252  that extends annularly in circumferential fashion about a rotor disk, such as, for example, the downstream rotor disk  107  described above with reference to  FIG. 1B . The cover plate  250  may also include, in various embodiments, a plurality of tabs  254  spaced circumferentially about a radially inner portion  256  of the cover plate  250 . Each tab within the plurality of tabs  254  is spaced circumferentially from an adjacent tab to form a plurality of slots  258  that are also spaced circumferentially about the radially inner portion  256 . In various embodiments, the cover plate  250  includes a web portion  260  extending radially between the radially inner portion  256  and a radially outer portion  262  of the cover plate  250 . In various embodiments, the web portion  260  includes a web face  261  that extends substantially radially between the radially inner portion  256  and the radially outer portion  262 , the web face  261  having a surface normal that is directed substantially parallel to a central longitudinal axis A. In various embodiments, a seal member  264 , that extends substantially axially, is configured to maintain a seal against an adjacent face of a rotor disk, such as, for example, the downstream rotor disk  107  described above with reference to  FIG. 1B . 
     Referring now to  FIG. 2D , an enlarged cross sectional view of the radially inner portion  256  of the cover plate  250 , including one of the plurality of tabs  254 , is provided. In various embodiments, the radially inner portion  256  of the cover plate  250  includes an aft face  266 . In various embodiments, the aft face  266  is configured for engagement with a corresponding face of an annular arm extending radially outward from a rotor disk, such as, for example, the second rear annular arm  149  of the downstream rotor disk  107 , described above with reference to  FIG. 1B . In various embodiments, the aft face  266  (together with the corresponding face of the annular arm) has a surface normal that is directed substantially parallel to the central longitudinal axis A. In various embodiments, the aft face  266  extends (in the vicinity of each of the plurality of tabs  254 ) from a radially inner tip portion  268  to a radially outer face portion  270 . In various embodiments, the radially inner tip portion  268  transitions into the aft face  266  by a first radial portion  272  defining a first radius of curvature  273 . Similarly, in various embodiments, the web face  261  transitions into the aft face  266  by a second radial portion  274 , positioned proximate or overlapping the radially outer face portion  270 , defining a second radius of curvature  275 . In various embodiments, the aft face  266  is offset from the web face  261  by an offset distance  265 , such that the aft face  266  extends in an axial direction into the radially inner portion  256  by the offset distance  265  with reference to the web face  261 . In various embodiments, the aft face  266  has a surface normal (or aft face normal) directed substantially parallel to the longitudinal axis. In various embodiments, either or both of the first radius of curvature  273  and the second radius of curvature  275  may be large (e.g., infinite), resulting in a substantially flat, chamfered-type geometry at either or both of the first and second radial portions. 
     Referring still to  FIG. 2D , the radially inner portion  256  includes an annular ring portion  280  that generally extends in an axial direction on a side of the cover plate  250  opposite the aft face  266 . In various embodiments, the annular ring portion  280  includes an angled forward face  281  that is oriented at a forward face angle  282  with respect to a cylindrical plane  283  (e.g., a cylinder) that is parallel to (or coaxial with) the central longitudinal axis A. In various embodiments, the forward face angle  282  is within a range from about fifty degrees (50°) to about eighty degrees (80°); in various embodiments, the forward face angle  282  is within a range from about fifty degrees (50°) to about seventy degrees (70°); and in various embodiments, the forward face angle  282  is about sixty degrees (60°). In various embodiments, the angled forward face  281  extends from a first forward face  284  of the radially inner tip portion  268  to a second forward face  285 . In various embodiments, the first forward face  284  transitions into the angled forward face  281  by a third radial portion  286  defining a third radius of curvature  287 . In various embodiments, the first forward face has a surface normal (or first forward face normal) directed substantially parallel to the longitudinal axis. Similarly, in various embodiments, the second forward face  285  transitions into the angled forward face  281  by a fourth radial portion  288  defining a fourth radius of curvature  289 . In various embodiments, the second forward face has a surface normal (or second forward face normal) directed substantially parallel to the longitudinal axis. In various embodiments, one or more of the first radius of curvature  273 , the second radius of curvature  275 , the third radius of curvature  287  and the fourth radius of curvature  289  are approximately equal to the offset distance  265 . In various embodiments, each of the plurality of slots  258  defines a slot face  203  that intersects the angled forward face  281  about half way along a length  279  of the angled forward face  281 . 
     Referring now to  FIGS. 3A and 3B , forward facing and aft facing views of a slot  358 , such as, for example, one of the slots within the plurality of slots  258  described above with reference to  FIG. 2A , are provided. Referring to  FIG. 3A , the slot  358  includes a chordal length  301  that is, in various embodiments, about equal to or greater than a corresponding chordal length of each of the plurality of tabs, such as the plurality of tabs  254  described above with reference to  FIG. 2A . The slot  358  is generally defined by a slot face  303  that extends along the chordal length  301  and transitions from a generally chordal and axially extending face to a generally radially and axially extending face at each of a first slot end  305  and a second slot end  307  of the chordal length  301 . A fifth radius of curvature  391  generally defines the transition of the slot face  303  at the first slot end  305  and the second slot end  307 . In various embodiments, a sixth radius of curvature  393 , together with the fifth radius of curvature  391 , define a compound radius for the transition from the chordal and axially extending face into the faces at the first slot end  305  and the second slot end  307 , where, in various embodiments, the sixth radius of curvature is less than the fifth radius of curvature. In various embodiments, the slot face  303  intersects an angled forward face  381 , such as, for example, the angled forward face  281  described above with reference to  FIG. 2D , along a forward intersection line  309 . In various embodiments, the forward intersection line  309  is defined by a forward intersection angle  311  where the angled forward face  381  and the slot face  303  intersect. In various embodiments, the forward intersection angle  311  is within a range from about one-hundred thirty degrees (130°) to about one-hundred degrees (100°); in various embodiments, the forward intersection angle  311  is within a range from about one hundred thirty degrees (130°) to about one-hundred ten degrees) (110°); and in various embodiments, the forward intersection angle  311  is about one hundred twenty (120°). In various embodiments, the forward intersection line  309  is defined by a sharp transition (e.g., an angled line defined by the intersection of two planes) between the angled forward face  381  and the slot face  303  with no or minimal chamfer or radius of curvature that would otherwise tend to smooth the forward intersection line  309 . In various embodiments, on either side of the slot  358  is disposed a radially inner tip portion  368  having a first forward face  384 , such as the radially inner tip portion  268  and the first forward face  284  described above with reference to  FIG. 2D . In various embodiments, the first forward face  384  transitions into the angled forward face  381  by a third radial portion  386  defining a third radius of curvature  387 , such as, for example, the third radial portion  286  described above with reference to  FIG. 2D . 
     Referring now to  FIG. 3B , in various embodiments, the slot face  303  intersects an aft face  366 , such as, for example, the aft face  266  described above with reference to  FIG. 2D , along an aft intersection line  313 . In various embodiments, the aft intersection line  313  is defined by an aft intersection angle  315  where the aft face  366  and the slot face  303  intersect. In various embodiments, the aft intersection angle  315  is within a range from about eighty degrees (80°) to about one-hundred degrees (100°); in various embodiments, the aft intersection angle  315  is within a range from about eighty five degrees (85°) to about ninety five degrees (95°); and in various embodiments, the aft intersection angle  315  is about ninety degrees (90°). In various embodiments, the aft intersection line  313  is defined by a gradual transition between the aft face  366  and the slot face  303 . In various embodiments, the gradual transition occurs with a chamfered or radiused portion that extends along and smooths the aft intersection line  313 . 
     Benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the disclosure. The scope of the disclosure is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. Different cross-hatching is used throughout the figures to denote different parts but not necessarily to denote the same or different materials. 
     Systems, methods and apparatus are provided herein. In the detailed description herein, references to “one embodiment,” “an embodiment,” “various embodiments,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments. 
     Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. 112(f) unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. 
     Finally, it should be understood that any of the above described concepts can be used alone or in combination with any or all of the other above described concepts. Although various embodiments have been disclosed and described, one of ordinary skill in this art would recognize that certain modifications would come within the scope of this disclosure. Accordingly, the description is not intended to be exhaustive or to limit the principles described or illustrated herein to any precise form. Many modifications and variations are possible in light of the above teaching.