GB2516445A

GB2516445A - A fuel spray nozzle

Info

Publication number: GB2516445A
Application number: GB1313035.6A
Authority: GB
Inventors: Simon Mark Joliff
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 2013-07-22
Filing date: 2013-07-22
Publication date: 2015-01-28
Also published as: GB201313035D0

Abstract

A fuel spray nozzle (fig 2) has a feed arm 2 with a cavity 12; an inlet fitting 4 which is welded 6 to an end of the feed arm 2; a seal carrier 30 in a fuel supply passage 16 of the inlet fitting 4; the carrier 30 receiving and sealed to an end of a fuel feed tube 14 in the arm; and (to allow access during overhaul) the seal carrier 30 able to be withdrawn through the fuel supply passage 16 away from the feed arm. The carrier can abut a flange 32 when installed, and include a calibrated fuel restrictor bore 42. Fuel supply passage 16 is in line with cavity 12.

Description

A FUEL SPRAY NOZZLE

This invention relates to a fuel spray nozzle, and is particulaily, although not exclusively, concerned with a fluid spray nozzle for a gas turbine engine.

Fuel spray nozzles are piovided in gas tuibine engines to supply fuel to one oi more combustors of the engine, and to deliver the fuel in the form of a spray for ignition within the combustor. A typical fuel spray nozzle compiises a feed aim which is provided with a nozzle head at one end and with an inlet fitting at the other end. The feed arm is supported in the engine by a burner ring so that the nozzle head opens into the combustor but with the inlet fitting situated outside the combustor for connection to fuel supply pipework. It is desirable to shield fuel flowing through the feed arm from the high temperatures which exist near the combustion chamber. Consequently, it is known to provide a cavity, referred to as a "tertiary cavity", within the feed arm and to convey the fuel in a fuel feed tube which extends through the cavity. Cooling air is supplied to the tertiary cavity to provide heat shielding for the fuel feed tube.

The fuel feed tube cooperates with the inlet fitting in a fluid-tight manner. The inlet fitting is welded to the feed arm, and this makes it difficult to obtain access to the tertiary cavity for servicing purposes, and in particular to replace seals and to remove any fuel residues which may have accumulated inside the tertiary cavity. In practice, the inlet fitting must be cut from the feed arm, and re-welded when overhaul is complete. This is expensive, and potentially introduces defects during the re-welding process.

It would be desirable for periodic overhaul of fuel spray nozzles to be possible without requiring cutting through and reinstatement of a welded connection between the feed arm and the inlet filling.

According to the present invention there is provided a fuel spray nozzle comprising a feed arm provided at one end with an inlet filling, in which a fuel feed tube extends from the inlet fitting along the feed arm, the fuel feed tube being in sealing engagement with a seal carrier which is mounted in the inlet fitting and is withdrawable from the inlet fitting in a direction away from the feed arm.

The inlet fitting may have a fuel supply passage within which the seal carrier is mounted. The seal carrier may be displaceable along the fuel supply passage for withdrawal from the inlet fitting.

The wall of the fuel supply passage may have an abutment which is engaged by the seal carrier to define an installed position of the seal carrier. The seal carrier may engage the fuel supply passage by a screwthreaded connection.

Sealing means, for example one or more sealing rings such as an 0-ring, may be provided to seal between the seal carrier and the inlet fitting. The sealing ring may be disposed between the seal carrier and the wall of the fuel supply passage.

The fuel feed tube may be received in a recess of a seal carrier, and sealing means, for example one or more sealing rings such as an 0-ring, may be provided to seal between the fuel feed tube and the seal carrier. The sealing ring may be disposed between the fuel feed tube and the wall of the recess.

The seal carrier may have a restrictor bore, which may be formed in the body of the seal carrier. Alternatively, the restrictor bore may be formed in a restrictor element which is fitted to the body of the seal carrier.

The inlet fitting may be secuied by welding to the feed arm. The fuel feed tube may extend through a cavity in the feed arm.

For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is partially cut away view of a turbofan gas turbine engine having a fuel spray nozzle according to the present invention.

Figure 2 is an enlarged cross-sectional through the fuel spray nozzle shown in figure 1.

Figure 3 is a fragmentary sectional view of a known fuel spray nozzle for a gas turbine engine: and Figure 4 corresponds to Figure 2 but shows a fuel spray nozzle for a gas turbine engine in accordance with the present invention.

A turbofan gas turbine engine 110, as shown in figure 1, comprises in flow series an intake 111, a fan 112, an intermediate pressure compressor 113, a high pressure compressor 114, a combustion chamber 115, a high pressure turbine 116, an intermediate pressure turbine 117, a low pressure turbine 18 and an exhaust 119. The high pressure turbine 116 is arranged to drive the high pressure compressor 114 via a first shaft 126. The intermediate pressure turbine 117 is arranged to drive the intermediate pressure compressor 113 via a second shaft 128 and the low pressure turbine 118 is arranged to drive the fan 112 via a third shaft 130. In operation air flows into the intake 111 and is compressed by the fan 112. A first portion of the air flows through, and is compressed by, the intermediate pressure compressor 113 and the high pressure compressor 114 and is supplied to the combustion chamber 115. Fuel is injected into the combustion chamber 115 and is burnt in the air to produce hot exhaust gases which flow through, and drive, the high pressure turbine 16, the intermediate pressure turbine 117 and the low pressure turbine 118. The hot exhaust gases leaving the low pressure turbine 18 flow through the exhaust 119 to provide propulsive thrust.

A second portion of the air bypasses the main engine to provide propulsive thrust. The combustion chamber 115 has a plurality of fuel spray nozzles ito supply fuel into the combustion chamber 115.

A fuel nozzle 1, as shown more clearly in Figure 2, comprises a feed arm 2 and a fuel nozzle head 3. The fuel nozzle head 3 locates in a corresponding aperture in the combustion chamber 115 and the feed arm 2 extends generally radially through a corresponding aperture 5 in a combustion chamber casing 6.

The fuel spray nozzle 1 shown in Figure 3 comprises a feed arm 2 to which an inlet fitting 4 is secured by welding at an interface 6. The feed arm 2 has a mounting flange 8 for securing the fuel spray nozzle 1 to the combustion chamber casing 6 of the gas turbine engine 110, and the inlet fitting 4 has, at its end away from the feed arm 2, formations 10 for connection to fuel supply pipework of the gas turbine engine 110.

The feed arm 2 has an internal tertiary cavity 12 which extends over the full length of the feed arm 2 from the inlet fitting 4 to a nozzle head (not shown). A fuel feed tube 14 extends within the cavity 12 to supply fuel from the inlet fitting 4 to the nozzle head.

The cavity 12 has an inlet (not shown) for cooling air which flows within the cavity 12 to the nozzle head, from which it is discharged into the combustion chamber. The flow of cooling air shields the fuel feed tube 14, and the fuel within it, from the high temperatures which prevail around the fuel spray nozzle.

The inlet fitting 4 has a fuel supply passage 16 having a cylindrical wall 18. At its lower end, as seen in Figure 3, the inlet fitting 4 has a seal carrier portion 20 which is an integral part of the body of the inlet fitting 4. The seal carrier portion 20 has a connecting passage 22 which is a continuation of the fuel supply passage 16 and connects the fuel supply passage 16 to the cavity 12. The fuel feed tube 14 is received within the connecting passage 22. An 0-ring 24 is received in a groove of the wall of the connecting passage 22 to provide a seal between the fuel feed tube 14 and the seal carrier portion 20.

A restrictor element 26 having a restrictor bore 42 is fitted within the connecting passage 22 at its junction with the fuel supply passage 16. An 0-ring 28 provides a seal between the restrictor element 26 and the seal carrier portion 20.

Fuel spray nozzles are subjected to periodic overhaul to maintain their performance. In the course of an overhaul, it is necessary to remove any fuel residue which has accumulated within the cavity 12, and to replace seals such as the 0-rings 24, 28.

Fuel may, for example, enter the cavity 12 past the 0-ring 24 should the 0-ring start to break down, or it can enter under some circumstances at the nozzle head. In order to gain access to the cavity 12, it is necessary to separate the inlet fitting 4 from the feed arm 2 by cutting through the weld at the interface 6. It is then possible to remove the feed tube 14. During re-assembly following replacement of the 0-rings 24, 28, the inlet fitting 4 is returned to the feed arm 2, and re-welded in place at the interface 6. This process is laborious and expensive, and creates the possibility that the new weld will be defective, so possibly leading to future failure of the fuel spray nozzle.

Figure 4 shows a modified fuel spray nozzle constructed in accordance with the present invention. Reference numbers used in Figure 3 are used again in Figure 4 to refer to corresponding components.

In the fuel spray nozzle of Figure 4, a separate seal carrier 30 is mounted in the body of the inlet fitting 4. The fuel supply passage 16 has a substantially continuous cylindrical wall 18 which terminates at the lower end of the inlet fitting 4 at an inturned flange 32 against which the seal carrier 30 abuts so as to define its installed position.

The seal carrier 30 has a cylindrical head portion 34 which fits within the fuel supply passage 16. The head portion 34 has an external groove 35 which holds an 0-ring 36 providing a seal between the head portion 34 and the wall 18 of the fuel supply passage 16.

The seal carrier 30 has a tube receiving portion 38 which projects from the head portion 34 past the flange 32 and through an opening 33 at the lower end of the cylindrical wall 18. The tube receiving portion 38 has a recess 40, which receives the upper end of the fuel feed tube 14, with sealing provided by an 0-ring 24 held in a groove 41 in the wall of the recess 40.

A restrictor bore 42 extends through the head portion 34 of the seal carrier 30, and provides communication between the fuel supply passage 16 and the recess 40.

The tube receiving portion 38 of the seal carrier 30 has an outer periphery which is smaller than the opening 33 within the interned flange 32. Consequently, it is possible to withdraw the seal carrier 30, and the fuel feed tube 14, through the fuel supply passage 16, without requiring separation of the inlet fitting 4 from the feed arm 2. As a result of this, the disadvantages associated with overhauling the fuel spray nozzle of Figure 3 are avoided, so that the process becomes simpler, less costly, and less prone

to the introduction of defects during re-assembly.

It will be noted also that, in the fuel spray nozzle of Figure 4, the fuel supply passage 16 is in line with the cavity 12, so providing easier access to the cavity 12 than is the case with the fuel spray nozzle of Figure 3.

The seal carrier 30 may be secured within the fuel supply passage 16 in any suitable manner, for example as a friction fit, by way of a screwthreaded connection, or by way of a separate retaining element. Although the restrictor bore 42 is formed in the body of the seal carrier 30, an alternative possibility is to provide the bore 42 in a separate restrictor element similar to the restrictor element 26 of Figure 3, which is fitted to the body of the seal carrier 30. The restrictor bore 42 is calibrated so as to achieve desired flow characteristics in the fuel spray nozzle, and in particular to ensure that all fuel spray nozzles in an injector array have the same flow number. The restrictor bore for any fuel spray nozzle may be changed by replacement of the entire seal carrier 30 by one having a restrictor bore 42 of the desired orifice size, or by replacing the restrictor element 26.

Claims

CLAIMS1. A fuel spray nozzle comprising a feed arm provided at one end with an inlet fitting, in which a fuel feed tube extends from the inlet fitting in the feed arm, the fuel feed tube being in sealing engagement with a seal carrier which is mounted in the inlet fitting and is withdrawable from the inlet fitting in a direction away from the feed arm.
2. A fuel spray nozzle as claimed in claim 1, in which the inlet fitting has a fuel supply passage within which the seal carrier is mounted.
3. A fuel spray nozzle as claimed in claim 2, in which the seal carrier is displaceable along the fuel supply passage for withdrawal of the seal carrier from the fuel supply passage.
4. A fuel spray nozzle as claimed in claim 2 or 3, in which the fuel supply passage is provided with an abutment for engagement by the seal carrier to define an installed position of the seal carrier.
5. A fuel spray nozzle as claimed in any one of claims 2 to 4, in which the seal carrier engages the fuel supply passage by a screwthreaded connection.
6. A fuel spray nozzle as claimed in any one of claims 2 to 5, in which sealing means is provided for sealing between the seal carrier and the inlet filling.
7. A fuel spray nozzle as claimed in any one of the preceding claims, in which the feed tube is received in a recess of the seal carrier.
8. A fuel spray nozzle as claimed in claim 7, in which sealing means is provided for sealing between the fuel feed tube and the seal carrier.
9. A fuel spray nozzle as claimed in any one of the preceding claims, in which the seal carrier has a restrictor bore.
10. A fuel spray nozzle as claimed in claim 9, in which the restrictor bore is formed in the body of the seal carrier.
11. A fuel spray nozzle as claimed in claim 9, in which the restrictor bore is provided in a restrictor element which is fitted to the body of the seal carrier.
12. A fuel spray nozzle as claimed in any one of the preceding claims, in which the inlet fitting is secured to the feed arm by welding.
13. A fuel spray nozzle as claimed in any one of the preceding claims, in which the fuel feed tube extends thiough a cavity in the feed aim.
14. A fuel spray nozzle substantially as described herein with reference to, and as shown in, Figure 4 of the accompanying diawings.