JPH05539B2 - - Google Patents

Description

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a fuel nozzle assembly for a gas turbine engine, and more particularly, to a fuel nozzle assembly for a gas turbine engine and, more particularly, to a fuel nozzle assembly including a fuel delivery tube and an annular air passageway surrounding and defining an annular air passage therebetween. The air supply pipe is biased into sealing engagement with the fuel supply pipe, and the difference in expansion between the air supply pipe and the fuel supply pipe causes the air supply pipe to The present invention relates to a fuel nozzle assembly for a gas turbine engine that provides a tight sealing engagement between conduits.

Description of the Prior Art A typical fuel nozzle assembly capable of separately delivering both air and fuel to a combustion chamber typically includes a fuel nozzle supported at one end and a conical fuel nozzle end attached to the other end. The fuel feed tube includes a feed tube and an air feed tube supported at the same end and surrounding the fuel feed tube in spaced apart relationship to define an annular air passageway. A vortex cap is threaded onto the free end of the air feed tube and is tightened such that a conical opening in the vortex cap sealingly engages a conical surface on the end of the fuel nozzle. . The vortex cap also has a plurality of small holes equiangularly spaced around its center to direct atomizing air from the air passages to the fuel exiting the fuel nozzle end in an outwardly diffusing conical pattern. It is designed to point in the direction of convergence.

The air delivered from the fuel nozzle assembly is used primarily only during ignition of the gas turbine engine to atomize the fuel, so it is predictable and yet the atomized fuel and air mixture is used in the fire cross. It is important to provide an atomizing air pattern that brings the overpipe and/or spark igniter into close proximity.

The fuel nozzle end injects fuel in a generally conical pattern that spreads outward. However, during low fuel flow rates, the pressure atomization of fuel is low and air is introduced through the vortex cap to further atomize the fuel injected by the fuel nozzle. In this manner, the pattern for the cone changes, resulting in a humped spray pattern with four radial protrusions. This additional mist variation ensures good distribution of the fuel and air mixture to ensure proper delivery of the fuel and air mixture to the turbine to propagate the combustion process in the turbine. and is necessary during ignition combustion to improve atomization of the fuel as it is introduced through the fuel nozzle in order to reduce the amount of unburned fuel emissions. After ignition combustion is complete, the atomizing air is shut off and only fuel is delivered through the fuel nozzle to continue the combustion process.

To ensure that the airflow atomizes or atomizes the fuel stream in the desired hump-like spray pattern during atomization, the airflow has the same geometry as the openings in the end of the fuel nozzle that guide the fuel. It flows through a plurality of pores that have a chemical orientation.

In the prior art devices described above, a conical surface is used because, once a conical seal is formed, it provides the best airtight seal available. However, in order for the conical seal to be a high quality hermetic seal, it was necessary to apply a finely ground paste to the conical fuel nozzle end prior to engaging the vortex cap to the fuel nozzle end. Also,
Most importantly, using a conical fuel nozzle end and vortex cap to provide such a sealing interface allows the fuel nozzle and vortex cap interface to close during axial expansion of the air feed tube. A gap will be formed on the surface. This results in a significant reduction in the performance of the fuel nozzle assembly for the desired atomized fuel spray characteristics. In addition, foreign matter may be formed between the above-mentioned holes, which further deteriorates the performance of the fuel nozzle assembly. Prior art devices also tend to clog the air delivery passageway with deposits that accumulate in the air delivery passageway and do not provide access to the air delivery passageway for removal of such deposits. An example of a prior art fuel nozzle having a conical engagement between a fuel delivery tube and a vortex cap is disclosed in commonly assigned US Pat. No. 4,154,056.

The problems identified with prior art devices can be traced back to the fact that the temperature of the material flowing through the fuel delivery line is typically about 100 degrees Fahrenheit. However, the temperature of the air in the space between the fuel and air feed tubes can reach approximately 600 degrees Fahrenheit. Due to the resulting temperature difference between the fuel feed pipe and the air feed pipe, the amount of expansion in the axial direction of the fuel feed pipe and the air feed pipe often changes, causing the end of the fuel nozzle and the air The conical seal between the feed tubes breaks, thus creating the aforementioned gap at the seal interface between the two. This gap becomes an area where foreign matter from the air flowing through it or carbon deposits caused by occasional backflow from the combustor accumulates.
This will prevent the gap from being resealed. The air supply pipe itself can also become clogged with foreign objects. During shutdown, the conical seal interface may become contaminated by fuel oil from the combustion nozzle end.

Therefore, any gap between the air feed pipe and the fuel nozzle end becomes an air leakage path that has a detrimental effect on the distribution of the atomizing air, resulting in unstable and unpredictable ignition characteristics. This results in the existence of an ineffective fuel/air pattern. If the air passage becomes heavily contaminated, the flow of atomizing air will be completely blocked, preventing ignition.

Additionally, once prior art combustion nozzle assemblies are installed and installed in the combustion chamber of a gas turbine engine, it becomes very difficult to mechanically clean the air delivery passageway to remove foreign material, making sealing boundaries difficult. This may cause surfaces to leak or blockage in air delivery lines.

SUMMARY OF THE INVENTION It is an object of the present invention to maintain a constant sealing interface between the fuel delivery tube and the air delivery tube without gaps during axial expansion of the air delivery tube. A fuel nozzle assembly for a gas turbine engine is provided.

Another object of the invention is that the seal interface between the fuel feed pipe and the air feed pipe is remote from the fuel spray point so that air leakage at the seal interface against fuel atomization or spraying is prevented. It is an object of the present invention to provide an integral fuel nozzle end and end cap for a fuel nozzle assembly such that the effects of

Another object of the present invention is to provide a fuel nozzle assembly that has an improved sealing interface between the air feed tube and the fuel feed tube so as to be airtight during axial expansion of the air feed tube. It is to be.

Yet another object of the present invention is to provide a fuel nozzle assembly such that the seal between the air feed tube and the support flange is enhanced during axial expansion of the air feed tube.

Yet another object of the present invention is to provide a fuel nozzle assembly that absorbs at least a portion of the axial expansion of the air delivery tube without adversely affecting the operation of the fuel nozzle.

The present invention also provides a fuel nozzle assembly for a gas turbine engine that prevents carbon deposits from accumulating at the interface between the fuel feed tube and the air feed tube during axial expansion of the air feed tube. It is intended to.

A further object of the present invention is to provide a fuel nozzle assembly, such as for a gas turbine engine, that minimizes contamination of the air feed line.

It is also an object of the present invention to create an airtight seal interface between the fuel feed tube and the air feed tube without applying pulverized paste to the end of the fuel nozzle.

Finally, it is another object of the invention to provide a fuel nozzle assembly in which the air delivery tube is easily removable so that the air passageway can be accessed for cleaning.

These and other objects and advantages are achieved by the present invention, which provides a fuel nozzle assembly for a gas turbine engine. The fuel nozzle assembly consists of a fuel feed tube substantially surrounded by an air feed tube. The fuel delivery tube has an integral fuel nozzle and end cap attached to its delivery end. The air feed tube substantially surrounds the fuel feed tube to define an air passageway therebetween. The integral fuel nozzle and end cap has a central opening and a small hole for the passage of atomizing air.
a central aperture through which fuel is injected from the fuel delivery tube, and the aforementioned small hole is aligned with the annular air passage of the fuel nozzle assembly to direct the air delivery. Air flowing through the tube flows through the aforementioned small holes to atomize the fuel exiting the fuel delivery tube, and the tongues allow for proper alignment of the end cap with the air delivery tube.

A support flange is provided for mounting a fuel delivery tube to a gas turbine engine. The support flange has an opening that accommodates the biasing spring. The biasing force of the spring biases the air delivery tube into a tight fit against the integral fuel nozzle and end cap of the fuel delivery tube. During expansion of the air feed tube, it expands along its axis, further strengthening the fit between them against the end cap on the one hand, and against the biasing force on the other hand. Absorbs expansion forces. Expansion of the air feed tube also strengthens the fit between the air feed tube and the support flange. Fluctuations in the axial expansion of the air and fuel feed tubes caused by extreme temperature differences between the air flowing through the air feed tube and the fuel flowing through the fuel feed tube are absorbed by the spring. or used to strengthen the seal or seal between the air feed pipe and the fuel feed pipe,
A strong seal is maintained between the air supply pipe and the fuel supply pipe, and no gap generation phenomenon occurs between the fuel supply pipe and the air supply pipe as seen in the prior art.

To provide a fuel nozzle assembly in which the atomizing air passageway is easily accessible for cleaning, and in which the fuel and air feed tubes are mounted together, the air feed tube is mounted on a spring. The biasing force biases the fuel delivery tube into positive alignment with the integral fuel nozzle and end cap. An integral fuel nozzle and end cap threaded onto the fuel feed tube can be easily removed from the fuel feed tube to free the air feed tube and provide easy access to the annular air passageway for cleaning. enable.

The present invention will be better understood, and its advantages and modes of use will become more readily apparent, from consideration of the following detailed description of the embodiments illustrated in the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1a and 1b, an end portion of a typical prior art fuel nozzle assembly 10 is illustrated. The fuel nozzle assembly 10 includes an inner fuel feed tube 12 and a surrounding outer air feed tube 14. The air feed pipe 14 is coaxial with the fuel feed pipe 12 and occupies substantially the same space. The fuel feed pipe 12 includes a feed end 13 with an axial opening, in which
A fuel nozzle end 15 is screwed onto the fuel feed pipe 12. The fuel nozzle end 15 has a conical surface 16 that engages the air feed tube 14. Air supply pipe 14
extends axially coaxially with the fuel feed pipe 12 and defines an annular air passage 18 between the outer wall of the fuel feed pipe 12 and the inner wall of the air feed pipe 14 over a common axial extent. is defined. Air supply pipe 14
The end 20 has a reduced outer diameter and is threaded to receive a vortex cap 22 therein.

Vortex cap 22 has a centrally located opening 24. This central aperture 24 is formed to define a tapered conical surface 26 . Further, the vortex cap 22 has a plurality of equally spaced holes formed around the vortex cap 22 to direct the atomizing air in a predetermined convergence direction to intersect the fuel from the fuel nozzle end 15 and atomize it. It has a small hole 28. The tapered conical surface 26 is sized to match the taper of the conical surface 16 of the fuel nozzle end 15 so that when the vortex cap 22 is tightened onto the air feed tube 14, the fuel nozzle end 15 extends into opening 24 and provides a sealed engagement between conical surfaces 16 and 26 when properly tightened. FIG. 1a shows a prior art fuel nozzle under normal temperature conditions, i.e., when there is no extreme temperature difference between the fuel flowing in the fuel feed pipe 12 and the air flowing in the air feed pipe 14. Assembly 10 is shown. As clearly shown in Figure 1a, if there is no temperature difference between the two feed pipes, the fuel feed pipe 12
and the air feed tube 14 is sealed at the interface between the fuel nozzle end 15 and the conical surface 26. Therefore, there are no gaps at the boundary and no contamination of the air passage 18 occurs. Air atomization of the fuel results in the desired hump-like spray pattern.

Returning to FIG. 1b, fuel nozzle assembly 10 is shown during axial expansion of the air feed tube caused by extreme thermal conditions during gas turbine operation. During normal gas turbine operation, combustion air from the compressor surrounds the air feed pipe 14, and this combustion air is approximately 600 to 700
℃). However, the fuel is about 100〓
(approximately 38°C), and the fuel supply pipe 12
The temperature is maintained lower than that of the air supply pipe 14. Therefore, since the extent to which the air feed pipe expands in the axial direction is greater than the amount of expansion of the fuel feed pipe, a gap 29 is created between the conical surfaces 16 and 26. Typically, the gap 29 between the conical surfaces 16 and 26 is
It can reach about 0.030in (0.762mm). Due to foreign matter in the air or back flow of combustion products into this gap, particulates can build up and clog the gap 29, thus causing extreme leakage between the feed pipes after the turbine has completed firing. Prevents the gap from closing when the temperature difference disappears. Therefore, before the next turbine ignition, a gap will already exist even if there is no temperature difference between the feed pipes. Air leakage from this gap can adversely affect the emission of the atomizing air stream, altering the spray pattern of the fuel nozzle assembly and altering the combustor light-off response.

Referring to FIG. 2, a combustion nozzle assembly 30 of the present invention is shown. This combustion nozzle assembly 3
0 is an inner fuel feed pipe 32 and an outer air feed pipe 3 extending axially from a support flange 36 at one end.
4. The air supply pipe 34 is connected to the fuel supply pipe 3
2 and occupy substantially the same space.

The fuel feed tube 32 has an axial opening and is internally threaded at each end. A fuel line (not shown) is typically coupled to the fuel inlet end (fuel inlet means) 40. The feed end 48 of the fuel feed tube 32 terminates in an integral fuel nozzle and end cap 49 threaded onto the fuel feed tube 32. The integral fuel nozzle and end cap 49 includes a threaded skirt 50 for attaching the integral fuel nozzle and end cap 49 to the feed end 48, a flange 51, and an air feed tube. end cap portion 53 engaging end portion 60 of 34;
and has. A sealing washer 52 is inserted between the flange 51 and the skirt portion 50,
Fuel oil is prevented from leaking from the fuel feed pipe 32. The end cap portion 53 has an opening 54 in the center which communicates with a central opening in the delivery end 48 for delivery of fuel from the fuel delivery tube 32. Furthermore, the end cap portion 53 includes an annular air passage 58.
The integral fuel nozzle and end cap 49 have small holes 56 equiangularly spaced around a central opening 54 communicating with the central opening 54 of the integral fuel nozzle and end cap 49 .
Air from the air passage (annular air chamber) 58 is fed through the small hole 56 in order to direct the atomizing air in a predetermined convergence direction such that it intersects and atomizes the fuel exiting the air passage. ing.

The air feed pipe 34 extends axially coaxially with the fuel feed pipe 32 and has an annular shape over a common axial extent between the outer wall of the fuel feed pipe 32 and the inner wall of the air feed pipe 34. It defines an air passage 58. The end 60 of the air feed tube 34 is fitted with an integral fuel nozzle and end cap in a manner to be described in more detail below to provide a seal between the air feed tube 34 and the fuel feed tube 32. 49 end cap portion (sealing means) 5
It is combined with 3.

A support flange 36 that attaches the fuel delivery tube to the gas turbine engine extends radially outwardly from the fuel delivery tube 32. This support flange 36
includes a radially extending atomizing air inlet 38 threaded to receive air piping (not shown).
Contains. The support flange also has an opening 4 for receiving a biasing spring (sealing means) 44.
Contains 2.

When the air feed tube 34 is attached to the fuel feed tube 32, the biasing spring 44 is compressed and exerts an axial force on the ramp washer 46. The ramp washer 46 acting through the split piston ring 47 then applies axial pressure to the air feed tube 34. Integral fuel nozzle and end cap 49
is attached to the fuel delivery tube 32 by threading its threaded skirt portion 50 into the delivery end 48 of the fuel delivery tube 32 until it is a snug fit. Once the integral fuel nozzle and end cap 49 is attached to the fuel delivery tube 32, the air delivery tube 34, under the influence of axial pressure from the biasing spring 44, The end cap portion 53 of the cap 49 is tightly fitted.
Therefore, since the fuel feed pipe 32 and the air feed pipe 34 are sealed from each other, leakage of atomization air that adversely affects fuel atomization does not occur.

Furthermore, the split piston ring 47 acting under the pressure exerted by the tapered washer 46 is attached to the common piston ring along with the support flange 36 so as to eliminate the gap between the support flange 36 and the air feed pipe 34. Generates radial pressure along the circumference. Therefore, air leakage that would otherwise occur at the interface between the support flange 36 and the air feed pipe 34 is prevented by the airtight seal or seal between the support flange 36 and the split piston ring 47. It disappears.

Alignment of the annular air passageway 58 and the eyelet 56 is provided by the tongue 62 of the end gap 53. When the threaded skirt 50 of the integral fuel nozzle and end cap 49 is tightened onto the fuel delivery tube 32, the protruding tongue 62 of the integral fuel nozzle and end cap 49 locks into the end 60. engages with the protruding tip 61 of. Projecting tip 61
Due to the engagement of the tongues 62 and 62, the fuel nozzle and end cap 49 integral with the air feed pipe 34 are aligned in the desired direction, and at the same time, the annular air passage 58 and the small hole 56 are aligned to form the air passage. Air flowing through 58 flows into small holes 56 .

When the fuel nozzle assembly 30 of the present invention is under normal temperature conditions, i.e., when there is no extreme temperature difference between the fuel flowing in the fuel feed line 32 and the air flowing in the air feed line 34, The fuel feed tube and the air feed tube have an integral fuel nozzle and end cap portion 53 of the end cap 49 and an end portion 60 of the air feed tube 34.
sealed or sealed at the interface with the There are no gaps at the interface and no contamination of the air passage 58 occurs. Air atomization of the fuel spray provides the desired humped spray pattern.

When the fuel nozzle assembly of the present invention experiences axial expansion in the air feed tube due to severe temperature conditions during gas turbine engine operation, the air feed tube 34 is more axial than the fuel feed tube 32. It extends widely in the direction. As the air feed tube 34 expands, the end 60 of the air feed tube 34 expands axially with respect to the end cap 53. The tight seal interface between end 60 and end cap 53 improves the seal between the two and prevents leakage of atomizing air. As the air supply pipe 34 continues to expand, the biasing spring 44 is compressed and the biasing spring 44 is compressed.
4 absorbs the axial expansion of the air feed tube 34 so that the seal between the fuel feed tube 32 and the air feed tube 34 does not separate. Furthermore, since the axial force increases due to the compression of the biasing spring 44, the radial pressure of the split piston ring 47 applied to the support flange 36 increases, thereby creating an airtight seal between the support flange 36 and the split piston ring 47. By strengthening the stop, air leakage at the interface between the support flange 36 and the air feed tube 34 is further reduced.

[Brief explanation of the drawing]

FIG. 1a is an axial cross-sectional view of the feed tube end of a typical conventional fuel nozzle assembly under normal operating conditions, and FIG. 1b is an axial cross-sectional view of the feed tube end of a typical conventional fuel nozzle assembly under normal operating conditions; FIG. FIG. 2 is an axial cross-sectional view of the feed tube end of the conventional fuel nozzle assembly of FIG. 30... Fuel nozzle assembly, 32... Fuel feed pipe, 34... Air feed pipe, 36... Support flange, 40... Fuel inlet means (fuel inlet end), 44
... sealing means (biasing spring), 48 ... feeding end of fuel feed pipe, 49 ... engaging means (integral fuel nozzle and end cap), 53 ... sealing means (end cap ), 58... annular air chamber (air passage), 60... end of air supply pipe.

Claims (1)

Claims: 1. A fuel feed tube having a feed end and fuel inlet means at an opposite end thereof; and a support flange attached to the fuel feed tube near the fuel inlet means. an air feed pipe having an end, the fuel feed pipe having one end in spaced relation to the fuel feed pipe for delivering air to the end of the air feed pipe; an air feed tube surrounding the support flange and extending axially from the support flange to define an annular air chamber between the fuel feed tube and the air feed tube; an engagement means attached to the air supply pipe and engaged with the end of the air supply pipe; and a sealing means for sealing the engagement portion between the end of the air supply pipe and the engagement means. A fuel nozzle assembly for a gas turbine engine, comprising: .