Patent Publication Number: US-2019195072-A1

Title: Turbine rotor disc having multiple rims

Description:
TECHNICAL FIELD 
     This disclosure relates to rotors for gas turbine engines, and, in particular to discs within a turbine section of a rotor. 
     BACKGROUND 
     Turbine sections of gas turbine engines typically include rotors having discs that connect to turbine blades. Typically, each rotor has a disc for each stage of turbine blades in the turbine section. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments may be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale. Moreover, in the figures, like-referenced numerals designate corresponding parts throughout the different views. 
         FIG. 1  illustrates a cross-sectional view of an example of a gas turbine engine; 
         FIG. 2  illustrates a front plan view of a first example of a disc; 
         FIG. 3  illustrates a partial cross-sectional side view of a second example of the disc; 
         FIG. 4  illustrates a partial cross-sectional side view of a third example of the disc; 
         FIG. 5  illustrates a partial cross-sectional side view of a fourth example of the disc; 
         FIG. 6  illustrates a partial cross-sectional side view of a fifth example of the disc; 
         FIG. 7  illustrates a side plan view of an example of the rim; and 
         FIG. 8  illustrates a flow diagram of an example of a method of manufacturing a disc. 
     
    
    
     DETAILED DESCRIPTION 
     Having a disc for each stage of turbine blades may increase the complexity of the turbine section, thus increasing the cost of the turbine engine and increasing the number of parts prone to failure within the engine. Additionally, having a disc for each stage of the turbine blades requires additional machining work as each disc must be machined. It is desirable that the rotor be less expensive, require fewer parts, and require less machining by having fewer discs. 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
     By way of an introductory example, a disc for use in a turbine rotor is provided, including a hub and a plurality of webs extending outwardly from the hub. Each of the plurality of webs are separate from each other by a gap. Each of the webs include a rim positioned at the outward end of the web, wherein the rims are each configured to receive a turbine blade. 
     One interesting feature of the systems and methods described below may be that the single disc may be cheaper to produce than a collection of traditional discs holding a similar number of turbine blades. Alternatively, or in addition, an interesting feature of the systems and methods described below may be that a rotor incorporating the disc may have fewer components than in traditional rotors, which may increase the durability and decrease the cost of the rotor. 
       FIG. 1  is a cross-sectional view of a gas turbine engine  74  for propulsion of, for example, an aircraft. Alternatively or in addition, the gas turbine engine  74  may be used to drive a propeller in aquatic applications, or to drive a generator in energy applications. The gas turbine engine  74  may include an intake section  82 , a compressor section  76 , a combustion section  78 , a turbine section  80 , and an exhaust section  84 . During operation of the gas turbine engine  74 , fluid received from the intake section  82 , such as air, travels along the direction D 1  and may be compressed within the compressor section  76 . The compressed fluid may then be mixed with fuel and the mixture may be burned in the combustion section  78 . The combustion section  78  may include any suitable fuel injection and combustion mechanisms. The hot, high pressure fluid may then pass through the turbine section  80  to extract energy from the fluid and cause a rotor  90  within the turbine section  80  to rotate, which in turn drives the a shaft  86  which drives the compressor section  76 . Discharge fluid may exit the exhaust section  84 . 
     As noted above, the hot, high pressure fluid passes through the turbine section  80  during operation of the gas turbine engine  74 . As the fluid flows through the turbine section  80 , the fluid passes between alternating turbine blades  30  and vanes  88  causing the rotor  90  to rotate. The rotor  90  may turn a shaft  86  in a rotational direction D 2 , for example. The turbine blades  30  may rotate around an axis of rotation, which may correspond to a centerline X of the rotor  90  in some examples. The centerline X may be a longitudinal axis which extends across the entire length of the rotor  90 , along the axis of rotation. The vanes  88  may remain stationary relative to the turbine blades  30  while the rotor  90  is rotating. The rotor  90  may be coupled to the turbine blades  30  by a disc ( 10  in  FIG. 2 ) which may extend outwardly from the rotor  90 . 
       FIG. 2  illustrates a front plan view of a first example of the disc  10  including a hub  12 , a web  14 , and a rim  16 . The disc  10  may be any component which couples to the rotor  90  and is configured to receive and rotate a set of the turbine blades  30 . Examples of the disc  10  may include a cone, a cylinder, or any shape having radial symmetry about the centerline X of the rotor  90 . The disc  10  may be made from any material capable of withstanding the radial forces and thermal stresses of operating in the turbine section  80 , such as titanium or stainless steel. All components of the disc  10 , including the hub  12 , the webs  14 , and the rim  16  may be made from a single forging and machining process. 
     The hub  12  may be the most inward portion of the disc  10  and may be any portion of the disc configured to be coupled to the rotor  90 . Examples of the hub  12  may include a cone, a cylinder, or any other radially symmetric shape. The hub  12  may be made from the same materials as any other portion of the disc  10 . The hub  12  may include an inner surface  28  defining a lumen  26  of the disc  10 . The rotor  90  may pass through the lumen  26  and be coupled to the hub  12  by the inner surface  28 . 
     The web  14  may be any portion of the disc  10  which extends outwardly from the hub  12 . Examples of the web  14  may include a cone, a cylinder, or any other radially symmetric shape. In some examples, the web  14  may be a solid plate that connects the hub  12  to the rim  16 . The web  14  may be made from the same materials as any other portion of the disc  10 . In embodiments wherein the hub  12  and the web  14  have different thicknesses, a hub transition  18  may exist between an outward end of the hub  12  and an inward end of the web  14  which smoothly transitions outwardly to match the thickness of the web  14 . 
     The rim  16  may be any portion of the disc  10  which forms the outward portion of the disc  10  and extends outwardly from the web  14 . Examples of the rim  16  may include a cone, a cylinder, or any other radially symmetric shape. The rim  16  may be made from the same materials as any other portion of the disc  10 . In embodiments wherein the web  14  and the rim  16  have different thicknesses, a rim transition  20  may exist between an outward end of the web  14  and an inward end of the rim  16  which smoothly transitions outwardly to the thickness of the rim  16 . The rim  16  may include an outer surface  22  configured to receive turbine blades  30  within grooves  24  formed in the outer surface  22 . The groove  24  may be any feature which may receive and secure a portion of the turbine blade  30 . Examples of the groove  24  may include a wedge-shaped slot, a circular trench, or a complex depression including sets of interacting teeth. 
       FIG. 3  illustrates a partial cross-sectional side view of a second example of the disc  10  including the hub  12 , a plurality of webs  14 , a plurality of rims  16 , where each of the rims  16  are coupled to a corresponding set of the turbine blades  30 . Each of the webs  14 , the rims  16 , and the sets of the turbine blades  30  may extend radially outwardly from a unitary hub  12  to form a respective stage of the turbine blades  30  within the turbine section  80  of the gas turbine engine  74 . The unitary hub  12  shown in  FIG. 3  may include as few as two webs  14 , or may extend the entire length of the turbine section  80 , such that every web  14  in the turbine section  80  extends from the single unitary hub  12 . In the embodiment shown in  FIG. 3 , the webs  14  are axially spaced apart from one another to form a gap  40  between each of the webs  14 . The gap  40  may be any space which separates the webs  14  and rims  16  sufficiently that a vane  88  may be arranged between the turbine blades  30  extending from each of the rims  16 . The webs  14  and the rims  16  may also have an internal surface  60  which defines the gap  40 . The internal surfaces  60  of the webs  14  may be meet at a trough  56  at the most inward point of the gap  40 . 
     Each of the webs  14  and rims  16  may also include an external surface  58  which is on an opposing side of the web  14  as the internal surface  60  of the web  14 . The external surface  58  may extend from the inner surface  28  of the hub  12  to the outer surface  22  of the rim  16 . The external surfaces  58  may be located at the first end  92  and the second end  94  of the disc  10 . Therefore, in some embodiments, such as when more than two webs  14  extending outwardly from the hub  12 , only the webs  14  at the first end  92  and second end  94  of the disc  10  may have external surfaces  58 . In such embodiments, the webs  14  located internally from the first end  92  and second end  94  of the disc  10  may have opposing internal surfaces  60  defining gaps  40  between webs  14  on either side of the web  14 . 
     The disc  10  may extend axially from a first end  92  to a second end  94 . As shown in  FIG. 3 , the disc  10  may include connectors  38  protruding from the hub  12  in some examples. The connectors  38  may be used to connect the disc  10  to additional discs  10  located upstream or downstream in the turbine section  80 . The connectors  38  may be formed as part of the hub  12 , or may be brazed or welded to the hub  12 . In alternative examples, the connectors  38  may not be needed to connect the discs  10  and may not be included in the disc  10 . 
     The disc  10  may also include retaining plates  32  configured to secure the turbine blades  30  to the rims  16 . The rims  16  may include an upward-facing notch  34  or other device to receive and secure the retaining plate  32  against an opposing downward-facing notch  36  in the turbine blade  30 . Once secured, the retaining plate  32  may prevent the turbine blade  30  from sliding axially out of the grooves  24  within the outer surface  22  of the rim  16 . The retaining plates  32  may be located on both sides of each turbine blade  30 , or just on one side. In some embodiments, the retaining plates  32  may not be utilized to secure the position of the turbine blades  30 . 
     The disc  10  may also include a spacer  62  which may span the gap  40  between the turbine blades  30  coupled to the rims  16 . Examples of the spacer  62  may include a ring, a cylinder, or a tube. The spacer  62  may be configured to contact the vanes  88  within the turbine section  80 . 
     The hub  12  may provide the primary structural support to the disc  10 . The web  14  and rim  16  may be less critical to the structure of the disc  10  and provide unnecessary weight to the disc  10 . Therefore, the hub  12  may have a thickness  42  which is greater than the thickness of any web  14  or rim  16  extending radially outwardly from the hub  12 . In some embodiments, as shown in  FIG. 3 , the thickness  42  of the hub  12  in an axial direction may be greater than the sum of all of the thickness of the webs  14  extending from the hub  12 . Similarly, in some embodiments, as shown in  FIG. 3 , the thickness  42  of the hub  12  in the axial direction may be greater than the sum of all of the thickness of the rims  16  extending radially from the hub  12 . In some examples, such configurations may maximize structural support for the disc  10  while minimizing the weight of the disc  10 . Additionally, as shown in  FIG. 3 , the rim  16  may have a greater thickness in the axial direction than the web  14  in order to accommodate and provide structural support to the turbine blades  30  that are coupled to the rim  16 . 
     In some embodiments, the thickness of the web  14  in the axial direction may decrease as the web  14  extends outwardly. In such embodiments, a width  48  of the gap  40  in the axial direction may increase as the gap  40  extends radially outwardly. The width  48  of the gap  40  in the axial direction may decrease between the web  14  and the rim  16 , as the rim transition  20  may cause the internal surface  60  to have a flare  52  to accommodate the larger thickness of the rim  16  as compared to the web  14 . 
     As shown in  FIG. 3 , in some embodiments, the thickness  42  of the hub  12  may be greater than a total rim thickness  46  of the disc  10 , wherein the total rim thickness  46  extending axially from the external surface  58  of the rim  16  located at the first end  92  of the disc  10  to the external surface  58  of the rim  16  located at the second end  94  of the disc  10 . Also shown in  FIG. 3 , in some embodiments, the total rim thickness  46  of the disc  10  may be greater than a total web thickness  44  of the disc  10 , wherein the total web thickness  44  extending from the external surface  58  inward from the rim  16  located at the first end  92  of the disc  10  to the external surface  58  inward from the rim  16  located at the second end  94  of the disc  10 . The total rim thickness  46  may increase between the web  14  and the rim  16 , as the rim transition  20  may cause the external surface  58  to have a flare  50  to accommodate the larger thickness of the rim  16 . 
       FIG. 4  illustrates a partial cross-sectional side view of a third example of the disc  10  including the hub  12 , a plurality of webs  14 , a plurality of rims  16 , and a plurality of turbine blades  30 . As shown in  FIG. 4 , in some embodiments, the width  48  of the gap  40  may be substantially uniform extending from an inward end of the web  14  to the outer surface  22  of the rim  16 . Additionally, as shown in  FIG. 4 , in some embodiments, the thickness  42  of the hub  12  may be substantially equal to the total rim thickness  46  of the disc  10 . In such embodiments, the stress on the disc  10  may be directed outward in a linear fashion to minimize any warping or bending that may occur during operation of the rotor  90 . 
       FIG. 5  illustrates a partial cross-sectional side view of a fourth example of the disc  10  including the hub  12 , a plurality of webs  14 , a plurality of rims  16 , and a plurality of turbine blades  30 . As shown in  FIG. 5 , in some embodiments, the thickness  42  of the hub  12  may be less than the total rim thickness  46  of the disc  10 . In such a configuration, the external surfaces  58  of the webs  14  and rims  16  may be angled or flared toward the first end  92  and second end  94  of the disc  10 . Such a configuration may put more bending stress on the webs  14  during operation of the rotor  90 , but the reduced thickness  42  of the hub  12  may decrease the weight of the disc  10 . 
     In some examples, as shown in  FIGS. 3-5 , the outer surfaces  22  of the rims  16 , which face radially outward may be substantially aligned with one another, such that the outer surfaces  22  are equidistant to the centerline X of the rotor  90 . Such a configuration may reduce the difficulty and cost of machining the disc  10 . 
       FIG. 6  illustrates a partial cross-sectional side view of a fifth example of the disc  10  including the hub  12 , the webs  14 , the rims  16 , and the turbine blades  30 . As shown in  FIG. 6 , in some embodiments, the outer surfaces  22  of the rims  16  may have an offset  64 , such that one outer surface  22  is inwardly closer to the centerline X of the rotor  90  than another outer surface  22 . Such a configuration may accommodate the layout of some turbine sections  80 . For example, some turbine sections  80  are arranged such that discs  10  must extend outwardly at increasingly greater distances the further the turbine section  80  proceeds downstream. In such a configuration, the embodiment of the disc  10  illustrated in  FIG. 6  may reduce the number of parts needed within the turbine section  80  and simplify the design of the rotor  90 , which may enhance the reliability of the rotor  90  and decrease the cost of the rotor  90 . 
     As shown in  FIG. 6 , the rim  16  which extends furthest from the centerline X of the rotor  90  may have the largest diameter and therefore, the largest circumference. In some embodiments, the portion of the turbine blades  30  coupled to the larger rim  16  may be equal to the portion of the turbine blades  30  coupled to the smaller rim  16 . However, in such a configuration, the distribution of turbine blades  30  coupled to the largest rim  16  would be less dense than the distribution of turbine blades  30  coupled to the smaller rim  16 . Alternatively, the portion of the turbine blades  30  coupled to the larger rim  16  may be greater than the portion of the turbine blades  30  coupled to the smaller rim  16 . In such a configuration, the distribution of turbine blades  30  coupled to the largest rim  16  may have equivalent or greater density when compared to the distribution of turbine blades  30  coupled to the smaller rim  16 . The number of turbine blades  30  on a rim  16  may vary from between 20 and 200. 
       FIG. 7  illustrates a side plan view of an example of the rim  16 . The outer surface  22  of the rim  16  includes the grooves  24  distributed about the circumference of the rim  16  and configured to receive turbine blades  30 . The grooves  24  may extend across the entire thickness of the rim  16 , from a first end  70  of the rim  16  to a second end  72  of the rim  16 . In some embodiments, the grooves  24  may have an angular offset  68  with respect to the centerline X of the rotor  90  to accommodate an offset aspect of the turbine blades  30  within turbine section  80 . Additionally, the angular offset  68  of the grooves  24  may vary as the rims  16  are positioned upstream or downstream within the turbine section  80 . 
       FIG. 8  illustrates a flow diagram of an example of a method of manufacturing the disc  10  for use in the rotor  90  of the gas turbine engine  74  ( 100 ). The steps may include additional, different, or fewer operations than illustrated in  FIG. 8 . The steps may be executed in a different order than illustrated in  FIG. 8 . 
     A plurality of rims  16  are formed ( 102 ) from the material comprising the disc  10 . A plurality of webs  14  are also formed ( 104 ), wherein each of the webs  14  are coupled to one of the rims  16 . A gap  40  is formed between each of the webs  14  and between each of the rims  16 . A hub  12  Is also formed ( 106 ) wherein each of the webs  14  is coupled to the hub  12 . 
     In some embodiments of the method ( 100 ), the disc  10  including the rims  16 , webs  14 , and unitary hub  12  may be formed from a single-forged workpiece or single-forged material. The single-forged workpiece may be any object comprising a forged uniform metallic material, such as stainless steel or titanium. Examples of the single-forged workpiece may include a block, a cylinder, or an irregular shaped chunk. The single-forged workpiece may be formed into the disc  10  by a number of methods such as milling, wherein the single-forged workpiece may be machined by a rotating tool, or by lathe turning, wherein the rotating single-forged workpiece may be machined by a tool. The outer surface of single-forged material may be initially smoothed, removing any surface irregularities from forging. In some embodiments, the disc  10  is formed from the most outward portions and proceeding inwardly. For example, the outwardly most portions of the disc  10 , the rims  16  may be formed before the webs  14 . Similarly the webs  14  may be formed before forming the unitary hub  12  of the disc  10 . The lumen  26  of the disc may be formed initially to accommodate lathe turning machining or may be formed at any other point in the machining process. 
     The method ( 100 ) may further include forming the grooves  24  in the outer surface  22  of the rim  16 . The grooves  24  may be formed using a variety of techniques such as milling or electrical discharge machining. One method of forming the grooves may include linearly broaching the grooves  24  using a shaped broach bar. Where the angular offset  68  of the grooves  24  is low and the offset  64  between the outer surfaces  22  of the plurality of rims  16  is low, a single broach bar may be used through the plurality of rims  16  in a single operation, reducing the complexity, difficulty, and cost of the machining process. 
     Each component may include additional, different, or fewer components. For example, the disc  10  may include more than two webs  14  extending outwardly from the unitary hub  12 . Additionally, in some embodiments, the webs  14  may not be present. Instead, a plurality of rims  16  would extend directly outward from the unitary hub  12 , forming the gap  40  and receiving the blades  30 . 
     The method ( 100 ) may be implemented with additional, different, or fewer components. For example, in some embodiments of the method ( 100 ) the step of forming the plurality of webs ( 104 ) may be omitted. This may be particularly relevant in embodiments wherein a plurality of rims  16  extend directly outward from the unitary hub  12  eliminating the plurality of webs  14 . 
     The logic illustrated in the flow diagrams may include additional, different, or fewer operations than illustrated. The operations illustrated may be performed in an order different than illustrated. 
     To clarify the use of and to hereby provide notice to the public, the phrases “at least one of &lt;A&gt;, &lt;B&gt;, . . . and &lt;N&gt;” or “at least one of &lt;A&gt;, &lt;B&gt;, . . . &lt;N&gt;, or combinations thereof” or “&lt;A&gt;, &lt;B&gt;, . . . and/or &lt;N&gt;” are defined by the Applicant in the broadest sense, superseding any other implied definitions hereinbefore or hereinafter unless expressly asserted by the Applicant to the contrary, to mean one or more elements selected from the group comprising A, B, . . . and N. In other words, the phrases mean any combination of one or more of the elements A, B, . . . or N including any one element alone or the one element in combination with one or more of the other elements which may also include, in combination, additional elements not listed. 
     While various embodiments have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible. Accordingly, the embodiments described herein are examples, not the only possible embodiments and implementations. 
     The subject-matter of the disclosure may also relate, among others, to the following aspects: 
     1. A disc for use in a turbine rotor, comprising: 
     a hub; and 
     a plurality of webs extending radially outwardly from the hub, wherein each of the plurality of webs is separated from another of the webs by a gap; and 
     a plurality of rims, wherein each rim is positioned at an outward end of one of the webs, wherein each rim is configured to receive a respective set of turbine blades. 
     2. The disc of claim  1 , wherein the webs include a first web and a second web, and wherein the first web extends radially outward at a first end of the disc and the second web extends radially outward at a second end of the disc, each of the first web and the second web comprising an internal surface and an external surface, wherein the internal surface of the first web and the internal surface of the second web define the gap between the first web and the second web.
 
3. The disc of claim  2 , wherein the disc further comprises a total rim thickness extending between the first end of the disc at the rim of the first web and the second end of the disc at the rim of the second web and a hub thickness at the hub of the disc which is less than the total rim thickness.
 
4. The disc of claim  2 , wherein the external surface of the first web at the rim and the external surface of the second web at the rim are flared such that a total rim thickness extending between the first end of the disc at the rim of the first web and the second end of the disc at the rim of the second web is greater than a total web thickness between the external surface of the first web inward from the rim and the external surface of the second web inward from the rim.
 
5. The disc of claim  2 , wherein a width of the gap between the internal surface and the first web and the internal surface of the second web increases as the gap extends outwardly.
 
6. The disc of claim  2 , wherein a width of the gap is substantially uniform from an inward end of each of the first web and second web extending outwardly to the outward ends of each of the first web and the second web.
 
7. A rotor of a gas turbine engine comprising,
 
     a disc comprising a unitary hub, a plurality of webs extending outwardly from the unitary hub, and a plurality of rims, wherein each of the plurality of webs is spaced apart from each other, and wherein each of the plurality of rims is positioned at an outward end of each of the webs; and 
     a plurality of turbine blades, wherein each turbine blade is coupled to one of the rims. 
     8. The rotor of claim  7 , wherein the disc extends from a first end of a turbine section of the gas turbine engine to a second end of the turbine section of the gas turbine engine.
 
9. The rotor of claim  7 , wherein each rim comprises an outer surface, wherein a first outer surface of a first rim is inwardly closer to a center of the disc than a second outer surface of a second rim.
 
10. The rotor of claim  9 , wherein a first portion of the plurality turbine blades coupled to the first rim is less than a second portion of the turbine blades coupled to the second rim.
 
11. The rotor of claim  9 , wherein the disc comprises a longitudinal axis extending through the center of the disc, wherein the plurality of turbine blades are coupled to the first rim and the second rim by a plurality of grooves formed in the outer surfaces of each of the first rim and the second rim, and wherein the plurality of grooves on the outer surface of the first rim are angularly offset from the longitudinal axis of the disc at a first angle and the plurality of grooves on the outer surface of the second rim are angularly offset from the longitudinal axis of the disc at a second angle which is different from the first angle.
 
12. A method of manufacturing a disc for use in a rotor of a turbine engine, comprising:
 
     forming a plurality of rims; 
     forming a plurality of webs, wherein each of the plurality of webs is coupled to one of the plurality of rims, and wherein a gap is formed between each of the plurality of webs and each of the plurality of rims; and 
     forming a hub, wherein each of the plurality of webs is coupled to the hub. 
     13. The method of claim  12 , further comprising forming a plurality of grooves into each of the rims, wherein each of the grooves is shaped to receive a turbine blade.
 
14. The method of claim  13 , wherein the plurality of grooves are formed by linear broaching.
 
15. The method of claim  14 , further comprising broaching a groove in a first rim of the plurality of rims and broaching a groove in a second rim of the plurality of rims in a single operation using a broach bar configured to extend across the first rim and the second rim.
 
16. The method of claim  13 , wherein the plurality of grooves are formed by milling.
 
17. The method of claim  13 , wherein the plurality of grooves are formed by electrical discharge machining.
 
18. The method of claim  12 , wherein the plurality of rims, the plurality of webs, and the hub are formed from a single-forged material.
 
19. The method of claim  18 , wherein the plurality of rims, plurality of webs, and the hub are formed from lathe turning of the single-forged material.
 
20. The method of claim  18 , wherein the plurality of rims, plurality of webs, and the hub are formed from milling of the single-forged material.