BACKGROUND

The described subject matter relates generally to ground-based turbine engines and more specifically to fluid systems for turbine bearings.

Industrial gas turbine engines, and other gas turbine engines utilize a power turbine or an alternate means for rotatably driving a power conversion device. Lubrication and air supply lines for the power turbine shaft bearings are typically mounted externally along the bearing compartment and the rest of the power turbine assembly. While this makes the supply lines accessible, external mounting subjects the large diameter lines to damage during delivery and during other maintenance tasks.

SUMMARY

A turbine module comprises a turbine shaft, a rotor assembly secured to the shaft, a bearing assembly rotatably supporting the turbine shaft, a bearing housing containing the bearing assembly, and a bearing compartment containing the bearing housing. The bearing compartment includes a wall having at least one integral fluid supply passage in fluid communication with the bearing housing. The at least one integral fluid passage extends generally longitudinally through the bearing compartment wall.

A turbomachine bearing compartment comprises a first wall section, a fluid supply inlet disposed proximate a first wall end surface, a fluid supply outlet formed through a first wall inner surface; and a first integral passage segment incorporated into the first wall section between first inner and outer wall surfaces. The first integral passage segment extends generally longitudinally through at least a portion of the first wall section and provides communication between the fluid supply inlet and the fluid supply outlet.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 depicts an example industrial gas turbine engine.

FIG. 2 shows a detailed cross-section of a power turbine section.

FIG. 3 is a detailed sectional view of an example power turbine bearing compartment.

FIG. 4 shows a forward facing radial cross-section of the power turbine bearing compartment housing including integrated longitudinal fluid supply lines. DETAILED DESCRIPTION

FIG. 1 is a simplified partial cross-sectional view of gas turbine engine 10, comprising inlet 12, compressor 14 (with low pressure compressor 16 and high pressure compressor 18), combustor 20, engine turbine 22 (with high pressure turbine 24 and low pressure turbine 26), turbine exhaust case 28, power turbine module 30, low pressure shaft 32, high pressure shaft 34, and power shaft 36. Gas turbine engine 10 can, for instance, be an industrial power turbine.

Low pressure shaft 32, high pressure shaft 34, and power shaft 36 are situated along rotational axis A. In the depicted embodiment, low pressure shaft 32 and high pressure shaft 34 are arranged concentrically, while power shaft 36 is disposed axially aft of low pressure shaft 32 and high pressure shaft 34. Low pressure shaft 32 defines a low pressure spool including low pressure compressor 16 and low pressure turbine 26. High pressure shaft 34 analogously defines a high pressure spool including high pressure compressor 18 and high pressure turbine 24. As is well known in the art of gas turbines, airflow F is received at inlet 12, is pressurized by low pressure compressor 16 and high pressure compressor 18. Fuel is injected at combustor 20, where the resulting fuel-air mixture is ignited. Expanding combustion gasses rotate high pressure turbine 24 and low pressure turbine 26, thereby driving high and low pressure compressors 18 and 16 through high pressure shaft 34 and low pressure shaft 32, respectively. Although compressor 14 and engine turbine 22 are depicted as two-spool components with high and low sections on separate shafts, single spool or 3+ spool embodiments of compressor 14 and engine turbine 22 are also possible. Turbine exhaust case 28 carries airflow from low pressure turbine 26 to power turbine module 30, where this airflow drives power shaft 36. Power shaft 36 can, for instance, drive an electrical generator, pump, mechanical gearbox, or other accessory (not shown).

FIG. 2 shows a detailed cross-section of power turbine module 30 and also includes turbine shaft 36, rotor assembly 38, airfoils 42, rotor disks 44, shaft forward end 46A, shaft aft end 46B, power turbine exhaust case (PTEC) 48, bearing housing 50, bearing compartment 52, fluid supply passages 54, bearing compartment wall 56, main bearing assembly 58, secondary bearing assemblies 60, exit duct 62, and return 64.

The turbine module shown in FIG. 2 is described with reference to an example power turbine module such as power turbine module 30 of the example industrial gas turbine engine 10 shown in FIG. 1. However, it will be appreciated that various embodiments of a turbine module and its associated components can be adapted to other turbine sections of gas turbine engine 10, such as high pressure turbine 24 and low pressure turbine 26. Additionally or alternatively, embodiments of a turbine module and associated components can be adapted to turbine sections of other gas and steam turbine engines.

In FIG. 2, the example power turbine module 30 includes turbine shaft 36 rotatable about center line, or axis A. Rotor assembly 38 is secured to power turbine shaft 36. In this example, rotor assembly 38 includes several rotor stages each including a plurality of airfoils 42 circumferentially distributed around each rotor disk 44. Working gas C is directed through power turbine module 30 to rotate rotor assembly 38, which drives power turbine shaft 36 from shaft forward end 46A. Working gas C is exhausted out from power turbine exhaust case (PTEC) 48. Power turbine shaft 36 is rotatably supported aft of rotor assembly 38 by one or more power turbine bearing assemblies retained in bearing housing 50. One or more pieces of industrial equipment such as an electrical generator or mechanical pump (not shown) can be secured to shaft aft end 46B to be driven by power turbine module 30.

FIG. 2 also shows bearing housing 50 secured in bearing compartment 52. In the example shown, one or more fluid supply passages 54 can be incorporated into various portions of bearing compartment wall 56 to be in fluid communication with one or more axially spaced apart bearing assemblies disposed within bearing housing 50. Main bearing assembly 58 and secondary bearing assemblies 60 are axially spaced apart along the length of bearing compartment 58. Lubricant is communicated from fluid supply passages 54 to each bearing assembly 58, 60. Used lubricant is flung outward by the bearings toward bearing housing 50, where it is collected and returned to the engine oil system through exit duct 62 and return line 64.

As seen in FIG. 2, integral passages 54 can include or more integral passage segments formed longitudinally within bearing compartment wall 56. Fluid lines, often carrying lubricant, air, and other fluids for a turbine module, are usually separately mounted primarily on the outside of the bearing compartment. While this makes the supply lines accessible, it also subjects these lines to environmental damage during transport and during unrelated maintenance tasks. However, integral passages 54 simplify more complicated repair and maintenance tasks on the turbine module (e.g., power turbine module 30) by reducing steps required to protect (or remove and reinstall) individual external fluid lines. In larger installations, it is typical for workers to climb onto and over the turbine case in order to access certain components. By moving the fluid lines into the case, it improves worker safety and reduces the need to protect the external lines from accidental damage (e.g., from workers tripping or from dropped tools). It also eliminates the need to protect the external lines from being damaged during transport of the turbine module (e.g., for off-site repairs and major overhauls).

FIG. 3 shows a more detailed view of example bearing compartment 52 for power turbine module 30 having one or more integral fluid supply passages 54 incorporated into bearing compartment wall 56. FIG. 3 also includes exit duct 62, return line 64, forward wall section 66A, aft wall section 66B, transition wall section 68, shaft passage 70, forward bearing compartment inner surface 72A, aft bearing compartment inner surface 72B, forward bearing compartment outer wall surface 74 A, aft bearing compartment outer wall surface 74B, lubricant supply outlets 76, main bearing housing portion 78A, secondary bearing housing portions 78B, forward integral fluid passage segment 80A, aft integral fluid passage segment 80B, passage inlets 82A, 82B, mounting surface 84, transition passage 86, supply pipes 88, fitting 90, plug 91, bearing compartment end walls 92A, 92B, and drain 93. Power turbine shaft 36 (shown in FIG. 2) is omitted for clarity.

In this example, bearing compartment wall 56 includes forward wall section 66A and aft wall section 66B connected by transition wall section 68. Wall 56 can additionally or alternatively be divided into upper and lower halves (shown in FIG. 4) so that each half of bearing compartment outer wall 56 can be sand cast into a general U- shape or crescent shape. This defines the rough shape of shaft passage 70. Each half can be further machined so that bearing housing(s) 50 generally conform to forward bearing compartment inner surface 72A, and aft bearing compartment inner surface 72B. Forward wall section 66A can be defined relative to forward inner wall surface 72A and forward outer wall surface 74A. Aft wall section 66B can be similarly defined relative to aft inner wall surface 72B and aft outer wall surface 74B.

Fluid supply passages 54 provide lubricant to main bearing assembly 60 and secondary bearing assemblies 62 (shown in FIG. 2) via one or more lubricant supply outlets 76 in communication with bearing housing(s) 50. In this example, axially spaced apart supply outlets 76 are disposed axially along an upper half of bearing housing 50 proximate main bearing housing portion 78A and secondary bearing housing portions 78B.

Each integral fluid supply passage 54 can include one or more segments formed in different sections of wall 56. In the example of FIG. 3, fluid supply passage 54 includes forward integral fluid passage segment 80A incorporated into forward wall section 66A, and aft integral fluid passage segment 80B incorporated into aft outer wall section 66B. In certain embodiments, aft integral passage segment 80B is longitudinally spaced apart from and/or circumferentially aligned with forward integral passage segment 80A. Spacing may depend, for example, on the relative nominal diameters of forward and aft wall sections 66A, 66B.

Large aspect ratios of passages 54 make it extremely difficult to machine them integrally into bearing compartment 52 (or a similar gas turbine case) without sacrificing structural integrity of wall 56. Accurate machining of the integral passage segments can thus be accomplished for example by gun-drilling or other laser-guided ballistic machining process in which deflection of the machine bit is minimized even at large aspect ratios. A specialized drill bit is configured to machine long narrow passages (e.g., with aspect ratios of more than 10:1) into solid metal substrates. Thus in certain embodiments, forward integral fluid passage segment 80 A can be formed into bearing compartment wall 56, e.g., by gun drilling longitudinally through forward wall section 66A from forward passage inlet 82A. FIG. 3 also shows optional aft integral fluid passage segment 80B, which also can be formed into bearing compartment wall 56, e.g., by gun drilling longitudinally through aft wall section 66B from aft passage inlet 82B.

In certain embodiments, forward wall section 66A has a smaller nominal diameter than aft wall section 66B to permit interconnection of power turbine module 30 to an adjacent turbine module (e.g., turbine exhaust case 28 and/or low pressure turbine 26 shown in FIG. 1). To secure the turbine modules to an adjacent module, wall transition section 68 can comprise flange or mounting surface 84 as shown in FIG. 3. Though shown with conventional bolt-type fasteners, this interconnection can additionally or alternatively include other modes of securing the two modules such as interference fittings. In alternative embodiments, transition wall section 68 can be stepped or tapered.

Forward and aft integral passage segments 80A, 80B can be interconnected by integral transition passage 86 to form a single effective integral passage 54. As shown in FIG. 3, integral transition passage 86 can be drilled at an angle from shaft passage 70 and forward wall inner surface 72A. This results in an angled fluid supply outlet 76.

In use, fluid can be received via forward passage inlet 82A and/or aft passage inlet

82B, depending on the configuration of power turbine module 30. In this example, supply pipes 88, which may be lubricant and/or buffer air supply lines, are engaged with suitable fluid-tight fitting(s) 90 metallurgically bonded to one or both bearing compartment end wall(s) 92 A, 92B. Plug 91 can also be inserted into forward or aft passage inlet 82A, 82B so as to maintain fluid pressure in the single effective integral passage 54 and prevent leakage. Alternatively, forward and aft integral fluid passage segments 80A, 80B operate as separate integral passages 54.

Received fluid can be communicated along forward integral fluid passage segment 80A to one or more of axially spaced apart main bearing assembly 58 and secondary bearing assemblies 60. Corresponding axially spaced apart fluid supply outlet(s) 76 respectively provide fluid communication between integral fluid passage segment(s) 80A, 80B, and the one or more bearing assemblies 58, 60. In the case of lubricant, used lubricant can collect in drains 93, and exit through duct 62 into return line 64.

FIG. 4 is a sectional view taken through main bearing assembly 60 (across line 4-

4 of FIG. 3) and viewed toward transition wall section 68. A plurality of circumferentially distributed fluid supply passages are incorporated into bearing compartment wall 56 around main bearing assembly 58. As was shown in FIG. 3, one or more of the plurality of fluid supply passages has at least one passage segment extending longitudinally through at least a portion of a cylindrical or frustoconical wall section. In FIG. 4, bearing compartment wall 56 is divided into upper and lower halves 94A, 94B which may be separately cast and fastened with bearing housing 50 retained therein.

Lubricant passage 95A is disposed above main bearing assembly 58 to supply fresh lubricant, while buffer air passage 95B is disposed through another portion of bearing compartment 52 and circumferentially spaced apart from lubricant passage 95 A. One or more gutters 96 are recessed into inner surface 97 of main bearing housing portion 78A, which passes the used lubricant toward drain 93 and into exit duct 62 and return line 64 (shown in FIG. 3). Gutter 96 can partially or completely circumscribe each bearing assembly (e.g., main bearing assembly 64). Additionally or alternatively gutter(s) 96 can be provided for secondary bearing assemblies 66 (shown in FIGS. 2 and 3).

As noted above, power turbine module 30 is one example turbine module for a large-scale gas turbine engine. Many such ground-based engines have a large nominal diameter to operate large-scale electrical machines or transport pumps. In certain embodiments, the entirety of the forward and/or aft wall sections each have a cross- sectional outer diameter measuring more than about 1.0 m (about 39 inches).

In certain embodiments, passage segments 88A, 88B can have a first longitudinal dimension along the forward wall segment, and a first cross-sectional diameter, a ratio of the first longitudinal dimension to the first cross-sectional diameter measuring at least about 10. The first cross-sectional passage diameter measures at least about 30 mm (about 1.2 inches). Larger embodiments have first cross-sectional passage diameter measuring at least about 75 mm (about 3.0 inches).

Since the economics of many ground-based industrial turbines rely on minimal downtime, integral fluid lines allow the turbine module to be removed, reassembled, and/or replaced quickly. Downtime is minimized in the event of an unplanned failure inside the turbine module that requires a swap of the turbine module. This is particularly useful during times of high short-term market demand (e.g., for electricity generation, fuel transport, etc.), where incremental performance is most valuable.

Discussion of Possible Embodiments

The following are non-exclusive descriptions of possible embodiments of the present invention:

A turbine module comprises a turbine shaft, a rotor assembly secured to the shaft, a bearing assembly rotatably supporting the turbine shaft, a bearing housing containing the bearing assembly, and a bearing compartment containing the bearing housing. The bearing compartment includes a wall having at least one integral fluid supply passage in fluid communication with the bearing housing. The at least one integral fluid passage extends generally longitudinally through the bearing compartment wall.

The apparatus of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:

A further embodiment of the foregoing turbine module, further comprising a plurality of axially spaced apart bearing assemblies, and a plurality of axially spaced apart fluid supply outlets in respective fluid communication with the bearing housing proximate each of the plurality of bearing assemblies.

A further embodiment of any of the foregoing turbine modules, wherein the bearing compartment comprises a first cylindrical or frustoconical wall section, and a second cylindrical or frustoconical wall section longitudinally adjacent to the first wall section.

A further embodiment of any of the foregoing turbine modules, wherein the bearing compartment further comprises a wall transition section connecting the first wall portion to the second wall portion, wherein the wall transition section includes at least one mounting surface for interconnecting the turbine module to a longitudinally adjacent module. A further embodiment of any of the foregoing turbine modules, wherein the fluid supply passage comprises a first integral passage segment extending generally longitudinally through at least a portion of the first wall section, a second integral passage segment extending generally longitudinally through at least a portion of the second wall section, and a transition passage segment disposed in the wall transition section interconnecting the first and second integral passage segments.

A further embodiment of any of the foregoing turbine modules, wherein the second integral passage segment is longitudinally spaced apart from the first integral passage segment.

A further embodiment of any of the foregoing turbine modules, wherein the second integral passage segment is circumferentially aligned with the first integral passage segment.

A further embodiment of any of the foregoing turbine modules, wherein the bearing compartment wall includes a plurality of circumferentially spaced apart integral fluid supply passages, each of the plurality of fluid supply passages including at least one passage segment extending generally longitudinally through at least a portion of a cylindrical or frustoconical wall section.

A turbomachine bearing compartment comprises a first wall section, a fluid supply inlet disposed proximate a first wall end surface, a fluid supply outlet formed through a first wall inner surface; and a first integral passage segment incorporated into the first wall section between first inner and outer wall surfaces. The first integral passage segment extends generally longitudinally through at least a portion of the first wall section and provides communication between the fluid supply inlet and the fluid supply outlet.

The apparatus of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:

A further embodiment of the foregoing bearing compartment, further comprising a plurality of axially spaced apart fluid supply outlets in communication with the first integral fluid supply passage.

A further embodiment of any of the foregoing bearing compartments, wherein the first integral passage segment has an aspect ratio of at least 10: 1. A further embodiment of any of the foregoing bearing compartments, further comprising a second cylindrical or frustoconical wall section longitudinally adjacent to the first wall section.

A further embodiment of any of the foregoing bearing compartments, further comprising a wall transition section connecting the first wall portion to the second wall portion.

A further embodiment of any of the foregoing bearing compartments, wherein the wall transition section includes at least one mounting surface for interconnecting the bearing compartment to a longitudinally adjacent turbine module.

A further embodiment of any of the foregoing bearing compartments, further comprising a second integral passage segment incorporated into the second wall section and extending generally longitudinally through at least a portion of the second wall section between second radially inner and outer wall surfaces.

A further embodiment of any of the foregoing bearing compartments, further comprising a transition passage segment interconnecting the first and second integral passage segments to define a contiguous integral fluid supply passage.

A further embodiment of any of the foregoing bearing compartments, wherein the second integral passage segment is longitudinally spaced apart from the first integral passage segment.

A further embodiment of any of the foregoing bearing compartments, wherein the second integral passage segment is circumferentially aligned with the first integral passage segment.

A further embodiment of any of the foregoing bearing compartments, wherein a cross-sectional diameter of the first integral passage segment measures at least about 30 mm (about 1.2 inches).

A further embodiment of any of the foregoing bearing compartments, wherein a cross-sectional diameter of the first wall section measures at least 1.0 m (about 39 inches).

Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.