Information
-
Patent Grant
-
6457316
-
Patent Number
6,457,316
-
Date Filed
Thursday, October 5, 200023 years ago
-
Date Issued
Tuesday, October 1, 200221 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Herkamp; Nathan D.
- Armstrong Teasdale LLP
-
CPC
-
US Classifications
Field of Search
US
- 060 740
- 060 742
- 060 746
- 060 776
- 239 400
-
International Classifications
-
Abstract
Gas turbine engine fuel nozzles are illustrated which induce swirling to fuel flowing to the engine to facilitate reducing fuel coking. Each fuel nozzle includes an inlet, an outlet and a fuel delivery system extending therebetween. The fuel delivery system includes an inner fuel supply tube and an outer fuel supply tube. The inner fuel supply tube is concentrically aligned within the outer fuel supply tube and includes contoured fuel passageways and a center axis of symmetry. As fuel enters the contoured passageways, the fuel is accelerated locally and directed angularly with respect to the axis of symmetry.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to fuel nozzles and, more particularly, to methods and apparatus for swirling fuel within fuel nozzles.
Gas turbine engines typically include a plurality of fuel nozzles for supplying fuel to the engine. Improving the life cycle of fuel nozzles installed within the turbine engine extends the longevity of the gas turbine engine. Known fuel nozzles include a delivery system and a support system. Each delivery system delivers fuel to the gas turbine engine and is supported and shielded within the gas turbine engine with the support system. The support system surrounds the delivery system and is thus subjected to higher temperatures than the delivery system which is cooled by the fluid flowing within the fuel nozzle.
Over time, continued exposure to high temperatures produced during gas turbine engine operation may induce thermal stresses on the fuel nozzles and/or facilitate fuel coking within the fuel nozzle. Fuel coking within the nozzle may cause fuel flow reductions and excessive fuel maldistribution within the gas turbine engine, which in-turn may result in turbine inefficiency, turbine component distress,, and reduced engine exhaust gas temperature margin.
To facilitate reducing the effects of the high temperatures, known fuel nozzles include thermal insulation mechanisms, and operate with high fuel flow rates to keep wetted surface temperatures below levels where coking can occur. Known thermal insulation mechanisms include external heat shields, and internal insulating cavities and heat shields which isolate fuel supply tubes from nozzle housing. Such insulation mechanisms add complexity to the fuel nozzle.
To further minimize the effects of high temperatures, during low power operations when high fuel flow rates are not demanded, dribble fuel is supplied to the fuel nozzles. The dribble fuel removes thermal energy from the delivery system that was induced from thermal soak-back of heat stored within the fuel nozzle support system. The additional fuel supplied as dribble fuel to the fuel nozzles may reduce turbine efficiency.
BRIEF SUMMARY OF THE INVENTION
In an exemplary embodiment, gas turbine engine fuel nozzles induce swirling to fuel flowing within the nozzles to facilitate a reduction in fuel coking. Each fuel nozzle includes an inlet, an outlet and a fuel delivery system extending therebetween. The fuel delivery system includes an inner fuel delivery tube and an outer fuel supply tube. The inner fuel supply tube is concentrically aligned within the outer fuel supply tube and includes contoured fuel passageways and a center axis of symmetry.
In use, fuel enters the fuel nozzle inlet and flows towards the contoured fuel passageways. As fuel enters the contoured passageways, the fuel is accelerated locally, and directed angularly with respect to the center axis of symmetry. The contoured passageways impart swirling on the fuel to produce a turbulated fuelflow downstream from the contoured passageways. The turbulated fuelflow facilitates reducing wetted wall temperatures downstream from the contoured passageway, thus lowering operating temperatures of the fuel nozzle. Lowering fuel nozzle operating temperatures facilitates reducing fuel coking within the fuel nozzle, regardless of the fuel flow rate through the fuel nozzle. As a result, the contoured fuel passageways facilitate reducing fuel coking within the gas turbine engine fuel nozzle.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a schematic illustration of a gas turbine engine;
FIG. 2
is a side schematic view of one embodiment of a fuel nozzle that could be used in conjunction with the gas turbine engine shown in
FIG. 1
; and
FIG. 3
is a side perspective view of a portion of the fuel nozzle shown in
FIG. 2
taken along area
3
.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1
is a schematic illustration of a gas turbine engine
10
including a low pressure compressor
12
, a high pressure compressor
14
, and a combustor
16
. In one embodiment, engine
10
is a GE90 engine available from General Electric Company, Cincinnati, Ohio. Engine
10
also includes a high pressure turbine
18
and a low pressure turbine
20
. In one embodiment, combustor
16
is a dual annular combustor that includes two radially stacked mixers (not shown) for each fuel nozzle
22
, which appear as two annular rings when viewed from the front of combustor
16
. Compressor
12
and turbine
20
are coupled by a first shaft
24
, and compressor
14
and turbine
18
are coupled by a second shaft
26
. A load (not shown) is also coupled to gas turbine engine
10
with first shaft
24
.
In operation, air flows through low pressure compressor
12
and compressed air is supplied from low pressure compressor
12
to high pressure compressor
14
. The highly compressed air is delivered to combustor
16
. Airflow from combustor
16
drives rotating turbines
18
and
20
and exits gas turbine engine
10
through a nozzle
28
.
FIG. 2
is a side schematic view of an exemplary embodiment of a fuel nozzle
40
that could be used a gas turbine engine, such as turbine. engine
10
(shown in FIG.
1
).
FIG. 3
is a side perspective view of fuel nozzle
40
taken along area
3
. More specifically,
FIGS. 2 and 3
illustrate an exemplary embodiment of fuel nozzle
22
(shown in
FIG. 1
) that could be used with a dual annular combustor
16
(shown in FIG.
1
). In the exemplary embodiment, dual annular combustor
16
includes two radially stacked mixers (not shown) for each fuel nozzle which appear as two annular rings when viewed from the front of the combustor. In an alternative embodiment, fuel nozzle
40
is any fuel nozzle used to supply fuel to a gas turbine engine.
A plurality of fuel nozzles
40
, each including a first end
42
and a second end
44
, are spaced circumferentially around the gas turbine engine to supply fuel to the gas turbine engine. Each fuel nozzle
40
also includes an inlet
52
that is adjacent fuel nozzle first end
42
, a first fuel outlet
54
that is adjacent fuel nozzle second end
44
, a second fuel outlet
56
, a fuel delivery system
60
, and a support system
62
.
Fuel delivery system
60
extends between fuel nozzle inlet
52
and fuel outlets
54
and
56
, and includes an inner fuel supply tube
66
and an outer fuel supply tube
68
. Inner fuel supply tube
66
extends from fuel nozzle inlet
52
within outer fuel supply tube
68
, such that inner fuel supply tube
66
is radially inward from and concentrically aligned with respect to outer fuel supply tube
68
. Inner fuel supply tube
66
is hollow and includes an inner surface
70
, an outer surface
72
, and an opening
74
extending therebetween. In the exemplary embodiment, inner fuel supply tube
66
has a substantially circular cross-sectional profile.
Outer fuel supply tube
68
circumferentially surrounds inner fuel supply tube
66
such that a chamber
80
is defined between inner and outer fuel supply tubes
66
and
68
, respectively. Outer fuel supply tube
68
includes an inner surface
82
, an outer surface
84
, and an opening
86
extending therebetween. In the exemplary embodiment, outer fuel supply tube
68
has a substantially circular cross-sectional profile.
A secondary fuel tube assembly
90
is in flow communication with fuel delivery system
60
and extends from fuel nozzle
40
between fuel nozzle inlet
52
and fuel nozzle first fuel outlet
54
. In one embodiment, fuel nozzle
54
is known as an outer tip fuel nozzle. More specifically, secondary fuel tube assembly
90
includes an inner tube
92
and an outer tube
94
that are in flow communication with respective inner and outer fuel supply tubes
66
and
68
. Inner and outer tubes
92
and
94
, respectively, connect to fuel nozzle
40
with a T-connection
96
such that each tube
92
and
94
extends substantially perpendicularly from fuel supply tubes
66
and
68
to fuel nozzle second fuel outlet
56
. Secondary fuel tube assembly inner fuel tube
92
is concentric with respect to secondary fuel tube assembly outer fuel tube
94
. In an alternative embodiment, fuel nozzle
40
does not include secondary fuel tube assembly
90
.
Inner and outer fuel supply tubes
66
and
68
, respectively, are aligned such that inner fuel supply tube opening
74
and outer fuel supply tube opening
86
are concentrically aligned within T-connection
96
. Accordingly, secondary fuel assembly
90
extends through fuel supply tube openings
74
and
86
to couple with fuel delivery system
60
.
Support system
62
extends between fuel nozzle first end
42
and fuel nozzle second end
44
to structurally support fuel nozzle delivery system
60
and shield fuel nozzle delivery system
60
from hot gases exiting a compressor, similar to compressor
14
(shown in FIG.
1
). More specifically, support system
62
extends circumferentially around fuel delivery system
60
such that an insulating cavity
110
is defined between support system
62
and fuel delivery system
60
. Insulating cavity
110
may contain any of the following: air, fuel, coked fuel, or other insulating materials.
Insulating cavity
110
circumferentially surrounds fuel delivery system chamber
80
and extends from fuel nozzle first end
42
to fuel nozzle second end
44
. Insulating cavity
110
is defined between support system
62
and delivery system
60
and thermally insulates delivery system
60
from support system
62
. Because insulating cavity
110
thermally insulates delivery system
60
and because fluid flow within fuel delivery system chamber
80
helps to cool fuel delivery system
60
, support system
62
is subjected to higher temperatures than delivery system
60
.
An annular swirler
112
extends circumferentially around fuel delivery inner tube
66
and includes a plurality of vanes
114
extending radially outward from an outer surface
116
, and an opening
118
. More specifically, swirler
112
extends around fuel delivery inner tube
66
at T-connection
96
. In one embodiment, annular swirler
112
is formed integrally with inner fuel supply tube
66
. In an alternative embodiment, fuel nozzle
40
does not include annular swirler
112
, but rather vanes
114
extend radially outward from inner fuel supply tube outer surface
72
. Accordingly, opening
118
is aligned concentrically with respect to inner fuel supply tube opening
74
.
Swirler vanes
114
extend radially outward from swirler outer surface.
116
and extend across swirler outer surface
116
between a first side
120
and a second side
122
of swirler
112
. Vanes
114
are aligned angularly with respect to a center axis of symmetry (not shown) of swirler
112
, such that vanes
114
are not parallel with respect to the center axis of symmetry, but vanes
114
are substantially parallel with respect to each other. Adjacent vanes
114
define a contoured fuel passageway
126
therebetween to turn fuel flowing through fuel nozzle
40
. In an alternative embodiment, vanes
114
extend radially inward from outer fuel supply tube inner surface
82
towards inner fuel delivery outer surface
70
.
In use, fuel supplied from a fuel source (not shown) enters fuel nozzles
40
through each fuel nozzle inlet
52
. Fuel flowing towards T-connection
96
through fuel nozzle delivery system
60
flows within fuel delivery chamber
80
. As fuel enters T-connection
96
, swirler vanes
114
redirect fuel to flow angularly with respect to the swirler center axis of symmetry. More specifically, fuel flowing through swirler
112
is accelerated locally within T-connection
96
, and vanes
114
impart swirling on the fuel that results in a turbulated fuelflow downstream from swirler
112
.
The swirl velocity induced by vanes
114
increases a convection coefficient for several tube diameters downstream from swirler
112
through second tube assembly
90
towards second fuel outlet
56
. The increased convection coefficient facilitates a reduction in fuel wetted wall temperatures downstream from swirler
112
, thus lowering operating temperatures of fuel nozzle
40
and facilitating a reduction in fuel coking within fuel nozzle
40
. In particular, during low fuel flowrate operating conditions, i.e., flowrates less than approximately 10 pph, the augmented convection coefficient decreases wetted wall temperatures despite the low fuel flowrate. Furthermore, because fuel nozzles
40
operate with lower operating temperatures, turbine engine exhaust gas temperatures are lowered and turbine efficiency is maintained.
The above-described gas turbine engine fuel nozzle is cost-effective and highly reliable. The fuel nozzle includes a swirler that induces swirling on the fuel flowing through the fuel nozzle. The induced swirling produces turbulated fuelflow downstream from the swirler that facilitates an increase in the fuel convection coefficient. As a result of the augmented convection coefficient, wetted wall temperatures downstream from swirler are lowered, thus facilitating a reduction in the operating temperature of the fuel nozzle. As a result, the swirler facilitates a reduction in fuel coking within the fuel nozzle in a cost-effective and reliable manner.
While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.
Claims
- 1. A method for supplying fuel to a gas turbine engine to facilitate reducing fuel coking within a fuel nozzle, the fuel nozzle including an inlet, a first discharge nozzle, a second discharge nozzle between the first discharge nozzle and the inlet such that the second discharge nozzle discharges fuel upstream from the first discharge nozzle, and a first fuel supply tube, said method comprising the steps of:supplying fuel to the first fuel supply tube through the fuel nozzle inlet; swirling fuel within the fuel nozzle by channeling the fuel through at least one vane; and channeling the swirling fuel to at least one of the first discharge nozzle and the second discharge nozzle.
- 2. A method in accordance with claim 1 wherein said step of swirling fuel further comprises the step of using a contoured fuel passageway to swirl the fuel within the fuel nozzle.
- 3. A method in accordance with claim 1 when e nozzle also includes an outer fuel supply tube, the first fuel supply tube housed concentrically within the outer fuel supply tube, said step of swirling fuel further comprises the step channeling fuel through a plurality of vanes that extend radially inward from an inner surface of the outer fuel supply tube towards an outer surface of the first fuel supply tube.
- 4. A method in accordance with claim 1 wherein the fuel nozzle also includes an outer fuel supply tube, the first fuel supply tube housed concentrically within the outer fuel supply tube, said step of swirling fuel further comprises the step of channeling fuel through a plurality of vanes that extend radially outward from an outer surface of the first fuel supply tube towards an inner surface of the outer fuel supply tube.
- 5. A method in accordance with claim 1 wherein step of swirling fuel further comprises the step of channeling fuel through an annular swirler attached circumferentially around the first fuel supply tube, such that a plurality of vanes extend radially outward from the inner fuel supply tube and induce swirling within the fuel.
- 6. A fuel nozzle for a gas turbine engine, said fuel nozzle comprising:an inlet; a first discharge nozzle; a second discharge nozzle between said inlet and said first discharge nozzle; and a fuel delivery system comprising a first fuel supply tube, said fuel supply tube extending between said fuel nozzle inlet and said first discharge nozzle, said fuel delivery system further comprising at least one vane configured to impart swirling to fluid flowing to at least one of said first and said second discharge nozzle through said fuel nozzle.
- 7. A fuel nozzle in accordance with claim 6 wherein said fuel supply tube comprises a contoured fuel passageway configured to impart swirling to fluid flowing through said fuel nozzle.
- 8. A fuel nozzle in accordance with claim 6 wherein said fuel delivery system further comprises an annular swirler concentric with said first fuel supply tube and configured to impart swirling to fluid flowing through said fuel nozzle.
- 9. A fuel nozzle in accordance with claim 8 wherein said swirler comprises a plurality of vanes and an outer surface, said vanes extending radially outward from said swirler outer surface.
- 10. A fuel nozzle in accordance with claim 8 wherein said seed discharge nozzle in flow communication with said fuel delivery system and configured to discharge swirling fuel therefrom.
- 11. A fuel nozzle in accordance with claim 10 wherein said second discharge nozzle extends radially outward from said swirler.
- 12. A fuel nozzle in accordance with claim 6 wherein said fuel delivery system further comprises an outer fuel supply tube extending circumferentially around said first fuel supply tube, said first fuel supply tube concentric with respect to said outer fuel supply tube.
- 13. A fuel nozzle in accordance with claim 12 wherein said outer fuel supply tube further comprises an inner surface and an outer surface, said outer fuel supply tube inner surface comprises a plurality of vanes extending radially inward from said inner surface and configured to impart swirling to fluid flowing through said fuel nozzle.
- 14. A gas turbine engine comprising at least one fuel nozzle configured to supply fuel to said gas turbine engine, said fuel nozzle comprising an inlet, a first outlet and a second outlet, and a fuel delivery system, said fuel delivery system comprising a first fuel supply tube, said fuel supply tube extending between said fuel nozzle inlet and said fuel nozzle first outlet, said fuel nozzle further comprising at least one vane configured to swirl fuel flowing to at least one of said first outlet and said second outlet through said fuel nozzle, said second outlet for discharging fuel from said nozzle upstream from said first outlet.
- 15. A gas turbine engine in accordance with claim 14 wherein said fuel nozzle fuel supply tube comprises a fuel passageway contoured to swirl fuel flowing through said fuel nozzle.
- 16. A gas turbine engine in accordance with claim 14 wherein said fuel nozzle fuel delivery system further comprises an outer fuel supply tube, said first fuel supply tube radially inward from said outer fuel supply tube and concentric with said outer fuel supply tube, at least one of said outer and first fuel supply tubes comprising a plurality of vanes configured to swirl fuel flowing through said fuel nozzle.
- 17. A gas turbine engine in accordance with claim 16 wherein said fuel delivery system outer fuel supply tube comprises an inner surface and an outer surface, said inner surface comprises a plurality of vanes extending radially inward towards said first fuel supply tube.
- 18. A gas turbine engine in accordance with claim 16 wherein said fuel delivery system inner fuel supply tube comprises an outer surface and an inner surface, said outer surface comprises a plurality of vanes extending radially outward towards said outer fuel supply tube.
- 19. A gas turbine engine in accordance with claim 14 wherein said fuel nozzle fuel delivery system further comprises an annular swirler concentric with said first fuel supply tube and configured to swirl fuel flowing through said fuel nozzle.
- 20. A gas turbine engine in accordance with claim 19 wherein said second outlet extends outward from said swirler.
US Referenced Citations (12)