WO2014028157A1

WO2014028157A1 - Rotor keyhole fillet for a gas turbine engine

Info

Publication number: WO2014028157A1
Application number: PCT/US2013/050686
Authority: WO
Inventors: Kevin L. Corcoran; Jody M. Grosso
Original assignee: United Technologies Corporation
Priority date: 2012-08-14
Filing date: 2013-07-16
Publication date: 2014-02-20
Also published as: US20140064976A1; EP2885521A1; EP2885521A4

Abstract

A rotor for a gas turbine engine includes an annular structure having a blade slot. A hub engagement feature is provided on the annular structure. The hub engagement feature includes first and second surfaces transverse to one another and joined by a fillet that is recessed with respect to the first and second surfaces. A method of manufacturing a rotor includes the steps of machining an annular hub engagement feature into a rotor. The hub engagement feature includes first and second surfaces transverse to one another and is joined by a fillet that is recessed with respect to the first and second surfaces. The method includes the step of peening the fillet, and grinding the first and second surfaces.

Description

ROTOR KEYHOLE FILLET FOR A GAS TURBINE ENGINE

BACKGROUND

[0001] This disclosure relates to a rotor for a gas turbine engine. More particularly, the disclosure relates to fillet geometry for the rotor.

[0002] A typical gas turbine engine includes multiple of compressor stages upstream from a combustor section. A turbine section is arranged downstream from the combustor. In one example configuration, at least one end of a compressor rotor is secured to a shaft by a hub. The hub engages a hub engagement feature on the rotor to secure the rotor relative to the shaft. Typically, a nut is received on the correspondingly threaded portion of the shaft and applies a clamping load to the rotor via the hub.

[0003] The hub engagement feature on the rotor is provided by first and second annular surfaces that are at a right angle to one another. A fillet joins the first and second surfaces, which are arranged tangentially relative to the fillet.

SUMMARY

[0004] In one exemplary embodiment, a rotor for a gas turbine engine includes an annular structure having a blade slot. A hub engagement feature is provided on the annular structure. The hub engagement feature includes first and second surfaces transverse to one another and joined by a fillet that is recessed with respect to the first and second surfaces.

[0005] In a further embodiment of any of the above, the first and second surfaces are normal to one another.

[0006] In a further embodiment of any of the above, the fillet includes a peened surface.

[0007] In a further embodiment of any of the above, the annular structure is constructed from a nickel alloy.

[0008] In a further embodiment of any of the above, the first and second surfaces are provided by ground surfaces. [0009] In a further embodiment of any of the above, the first and second surfaces are non-tangential to the fillet.

[0010] In another exemplary embodiment, a rotor assembly for a gas turbine engine includes a shaft. The rotor assembly includes a rotor that supports a blade and includes a hub engagement feature. The hub engagement feature includes first and second rotor surfaces transverse to one another and is joined by a fillet that is recessed with respect to the first and second rotor surfaces. A hub is supported on the shaft and engages the hub engagement feature.

[0011] In a further embodiment of any of the above, the rotor assembly includes a nut secured to the shaft and applies a clamping load to the hub engagement feature via the hub.

[0012] In a further embodiment of any of the above, the hub includes first and second hub surfaces respectively engaging the first and second rotor surfaces under the clamping load. The first and second hub surfaces are spaced from the fillet.

[0013] In a further embodiment of any of the above, the first and second rotor surfaces are normal to one another.

[0014] In a further embodiment of any of the above, the fillet includes a peened surface.

[0015] In a further embodiment of any of the above, the rotor is constructed from a nickel alloy.

[0016] In a further embodiment of any of the above, the first and second rotor surfaces are provided by ground surfaces.

[0017] In a further embodiment of any of the above, the first and second rotor surfaces are non-tangential to the fillet.

[0018] In another exemplary embodiment, a method of manufacturing a rotor includes the steps of machining an annular hub engagement feature into a rotor. The hub engagement feature includes first and second surfaces transverse to one another and is joined by a fillet that is recessed with respect to the first and second surfaces. The method includes the step of peening the fillet, and grinding the first and second surfaces.

[0019] In a further embodiment of any of the above, the grinding step is performed after the peening step. [0020] In a further embodiment of any of the above, the first and second surfaces are non-tangential to the fillet.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The disclosure can be further understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

[0022] Figure 1 is a schematic cross-sectional view of an example gas turbine engine.

[0023] Figure 2 is a schematic view of an example rotor and hub supported by a shaft.

[0024] Figure 3 is an enlarged cross-sectional view of a portion of the rotor and hub.

[0025] Figure 4 is a flow chart depicting an example method of manufacturing a rotor.

DETAILED DESCRIPTION

[0026] Figure 1 schematically illustrates an example gas turbine engine 20 that includes a fan section 22, a compressor section 24, a combustor section 26 and a turbine section 28. Alternative engines might include an augmenter section (not shown) among other systems or features. The fan section 22 drives air along a bypass flow path B while the compressor section 24 draws air in along a core flow path C where air is compressed and communicated to a combustor section 26. In the combustor section 26, air is mixed with fuel and ignited to generate a high pressure exhaust gas stream that expands through the turbine section 28 where energy is extracted and utilized to drive the fan section 22 and the compressor section 24.

[0027] Although the disclosed non-limiting embodiment depicts a turbofan gas turbine engine, 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; for example a turbine engine including a three-spool architecture in which three spools concentrically rotate about a common axis and where a low spool enables a low pressure turbine to drive a fan via a gearbox, an intermediate spool that enables an intermediate pressure turbine to drive a first compressor of the compressor section, and a high spool that enables a high pressure turbine to drive a high pressure compressor of the compressor section.

[0028] The example 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.

[0029] The low speed spool 30 generally includes an inner shaft 40 that connects a fan 42 and a low pressure (or first) compressor section 44 to a low pressure (or first) turbine section 46. The inner shaft 40 drives the fan 42 through a speed change device, such 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 high pressure (or second) compressor section 52 and a high pressure (or second) turbine section 54. The inner shaft 40 and the outer shaft 50 are concentric and rotate via the bearing systems 38 about the engine central longitudinal axis A.

[0030] A combustor 56 is arranged between the high pressure compressor 52 and the high pressure turbine 54. In one example, the high pressure turbine 54 includes at least two stages to provide a double stage high pressure turbine 54. In another example, the high pressure turbine 54 includes only a single stage. As used herein, a "high pressure" compressor or turbine experiences a higher pressure than a corresponding "low pressure" compressor or turbine.

[0031] The core airflow C 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. The turbines 46, 54 rotationally drive the respective low speed spool 30 and high speed spool 32 in response to the expansion. [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 ten (10), the geared architecture 48 is an epicyclic gear train, such as a star 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 5. 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 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. 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, with the engine at its best fuel consumption - also known as "bucket cruise Thrust Specific Fuel Consumption ('TSFC')" - is the industry standard parameter of lbm of fuel being burned per hour divided by lbf of thrust the engine produces at that minimum point. "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 [(Tambient deg R) / 518.7)^Λ0.5]. The "Low corrected fan tip speed" as disclosed herein according to one non-limiting embodiment is less than about 1150 ft / second.

[0034] Referring to Figure 2, the high pressure compressor 52 includes a rotor 60 supported relative to the outer shaft 50. In an example, the rotor 60 is the last stage disk of the high pressure compressor 52. The hub 62 supports the rotor 60 relative to the outer shaft

52. The hub 62 is secured to the outer shaft 50 by a nut 70, which applies a clamping force to a hub engagement feature 71 (discussed below) on the rotor 62. [0035] The rotor 60, which is constructed from a nickel alloy, includes one or more slots 65 that support multiple circumferentially spaced blades 64. It should be understood, however, that the blades 64 may be integrated with the rotor 60.

[0036] A first air seal 66 is supported by the rotor 60, in the example, which cooperates with a second air seal 68 supported by the engine static structure 36. The first air seal 66 may integral with or separate from the rotor 62.

[0037] The hub engagement feature 71 is shown in more detail in Figure 3. First and second rotor surfaces 72, 74 are provided on the rotor 60 normal (that is, perpendicular) to one another. The hub 62 includes first and second hub surfaces 76, 78 that also are normal with respect to one another. The first and second hub surfaces 76, 78 respectively engage the first and second rotor surfaces 72, 74 of the hub engagement feature 71. A fillet 80 joins the first and second rotor surfaces 72, 74 to one another. The fillet 80 is recessed with respect to the first and second rotor surfaces 72, 74 such that the first and second rotor surfaces 72, 74 are not tangential to the fillet 80. The first and second rotor surfaces 72, 74 meet the fillet 80 at first and second intersections 82, 84, respectively, providing a keyhole- shaped fillet geometry. Said another way, the first and second rotor surfaces 72, 74 are proud of, or extend above, the fillet 80. The first and second rotor surfaces 72, 74 extend toward the fillet 80 beyond the first and second hub surfaces 76, 78.

[0038] Referring to Figure 4, a method 86 of manufacturing the rotor 60 is described. The annular hub engagement feature 71 is machined into the rotor 60, as indicated at block 88. The hub engagement feature 71 includes the first and second rotor surfaces 72, 74, which are transverse to one another, for example, at a right angle. The fillet 80 may be machined at the same time as the first and second rotor surfaces 72, 74, subsequently to the first and second rotor surfaces 72, 74, or prior to forming the first and second rotor surfaces 72, 74. The fillet 80 is peened to relieve the stresses in this typically high stressed area, as indicated at block 90. The peening operation may occur before or after machining of the first and second rotor surfaces 72, 74. The first and second rotor surfaces 72, 74 may receive a finish grinding, as indicated at block 92, to provide a dimensionally precise surface with desired surface finish for receiving the hub 62.

[0039] Although an example embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of the claims. For that reason, the following claims should be studied to determine their true scope and content.

Claims

CLAIMS What is claimed is:

1. A rotor for a gas turbine engine comprising:

an annular structure having a blade slot; and

a hub engagement feature provided on the annular structure, the hub engagement feature including first and second surfaces transverse to one another and joined by a fillet that is recessed with respect to the first and second surfaces.

2. The rotor according to claim 1, wherein the first and second surfaces are normal to one another.

3. The rotor according to claim 1, wherein the fillet includes a peened surface.

4. The rotor according to claim 3, wherein the annular structure is constructed from a nickel alloy.

5. The rotor according to claim 3, wherein the first and second surfaces are provided by ground surfaces.

6. The rotor according to claim 1, wherein the first and second surfaces are non- tangential to the fillet.

7. A rotor assembly for a gas turbine engine comprising:

a shaft;

a rotor supporting a blade and including a hub engagement feature, the hub engagement feature including first and second rotor surfaces transverse to one another and joined by a fillet that is recessed with respect to the first and second rotor surfaces; and

a hub supported on the shaft and engaging the hub engagement feature.

8. The rotor assembly according to claim 7, comprising a nut secured to the shaft and applying a clamping load to the hub engagement feature via the hub.

9. The rotor assembly according to claim 8, wherein the hub includes first and second hub surfaces respectively engaging the first and second rotor surfaces under the clamping load, the first and second hub surfaces spaced from the fillet.

10. The rotor assembly according to claim 9, wherein the first and second rotor surfaces are normal to one another.

11. The rotor assembly according to claim 7, wherein the fillet includes a peened surface.

12. The rotor assembly according to claim 11, wherein the rotor is constructed from a nickel alloy.

13. The rotor assembly according to claim 11, wherein the first and second rotor surfaces are provided by ground surfaces.

14. The rotor assembly according to claim 7, wherein the first and second rotor surfaces are non-tangential to the fillet.

15. A method of manufacturing a rotor comprising the steps of:

machining an annular hub engagement feature into a rotor, the hub engagement feature including first and second surfaces transverse to one another and joined by a fillet that is recessed with respect to the first and second surfaces;

peening the fillet; and

grinding the first and second surfaces.

16. The method according to claim 15, wherein the grinding step is performed after the peening step.

17. The method according to claim 15, wherein the first and second surfaces are non-tangential to the fillet.