GB2101732A

GB2101732A - Gas turbine engine fuel injector

Info

Publication number: GB2101732A
Application number: GB08114531A
Authority: GB
Inventors: To Kwan William Ching; Desmond Close
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 1981-05-12
Filing date: 1981-05-12
Publication date: 1983-01-19

Abstract

A gas turbine engine fuel injector (32) has an air supply arranged to discourage the adherence of carbon particles. The air supply comprises a number of axial ducts (52) which take the air to a plenum chamber (50) and the air is discharged from the chamber (50) as a number of swirling flows of air through radial inclined slots or holes (58) (62) in an end cap (48). <IMAGE>

Description

SPECIFICATION Gas turbine engine fuel injector This invention relates to gas turbine engine fuel injectors and is concerned with providing a fuel injector having means for preventing or reducing the accretion of carbon particles.

Carbon particles are produced during the combustion process at certain engine operating conditions and become attached to parts of the engine combustion system, notably the fuel injector. The carbon particles agglomerate until lumps of solid carbon are formed which break free from the injector travel through the combustion system to impact upon the statics nozzle guide vanes and the rotating turbine blades, causing damage to these components.

The present invention seeks to provide a fuel injector having means enabling a flow of air wash over a surface to which carbon particles could become attached.

Accordingly the present invention comprises a gas turbine engine fuel injector having a fuel ductter- minating in a plurality of radially directed outlets, a housing having an open upstream end, a closed downstream end plurality of radially directed ducts, one of the fuel outlets being aligned with a respective one of said radial ducts, the housing being arranged to receive a flow of compressed air, and a flow of compressed air and fuel being arranged to flow through each one of said radial ducts, a ring of swirler vanes disposed around the housing upstream of the radial ducts through which compressed air is arranged to flow and impinge upon the flow of fuel and air leaving the radial ducts, the housing having an end cap at the downstream end thereof which with the housing defines a plenum chamber arranged to receive a flow of compressed air through a plurality of axial ducts, the end cap having a plurality of openings for the outlet of air from the plenum chamber.

The openings in the end cap may comprise a number of radial slots or groups of holes, the slots or holes being inclined at an acute angle to the face of the cap so that air leaving the end cap washes over the face of the cap.

The present invention will now be more particularly described with reference to the accompanying drawings in which: Figure 1 shows a gas turbine engine incorporating one form of fuel injector according to the present invention, Figure 2 is a view of one form of fuel injector according to the present invention and part of the combustion system of the engine shown in Figure 1, Figure 3 is a section on line 3-3 in Figure 2, Figure 4 is a view on arrow 'A' in Figure 2, and Figure 5 is a view similar to that in Figure but showing a modified form of injector.

Referring to the Figures, a gas turbine engine 10 comprises a fan 12 driven by a turbine 14, an intermediate pressure compressor 16 driven by an irtermediate pressure turbine 18, a high pressure compressor 20 driven by a high pressure turbine 22, and a combustion system 24. The air propelled by the fan 12 leaves the engine through an annular propulsion nozzle 26 and the hot gases from the turbines 14, 18, 22 exhaust through a propulsion nozzle 28.

The combustion system 24 comprises an annular combustion chamber 30 and a number of equispaced fuel injectors 32 which are located around the circumference of the combustion chamber at its upstream end so that the chamber 30 receives a flow of compressed air from the high pressure compressor 20 and a flow of fuel from the fuel injectors. An igniter or igniters (not shown) are provided to initiate combustion of the fuel.

Each fuel injector comprises a fuel duct 34 which terminates in a number of radial fuel outlets 36, and a housing 38 which is located inside a ring of air swirl vanes 40 which is attached to the head of the annular combustion 30. The housing 38 has an open upstream end 42 and a closed downstream end 44 and a number of radial ducts 44 located downstream of the swirl vanes 40. The fuel outlets 36 are are aligned with the ducts 46 so that compressed air from the compressor 20 which flows into the housing, can flow out through the ducts 46 with fuel from the outlets 36, the fuel and air mixture then meeting the flow of swirling air from the swirl vanes 40. Such an arrangement of fuel and air supply creates a rapid and even mixing of fuel and air.

When the mixture is burnt, carbon particles are formed during certain engine operating conditions, are formed during certain engine operating conditions, and these particles tend to adhere to the most downstream face of the injector. In order to discourage such carbon particles from adhereing to the injector, the housing 38 has an end cap 48 which with the end 44 of the injector forms a plenum chamber 50. The plenum chamber 50 is supplied with compressed airthrough a number of axial ducts 52 in the housing which, as shown in Figure 3 alternate with the radial ducts 48, and the ducts 52 are fed from a chamber 54 from a larger number of axial ducts 56.

The end cap 48 has a number of openings 58 for the outlet of airfrom the plenum chamber, in the form of radial slots which are inclined at an acute angle to the downstream face 60 of the cap 48.

As shown in Figure 5, the radial inclined slots can be replaced by groups of inclined holes 62, each group lying on an arcuate path. The holes 62 may be simplerto manufacture than the slots 58 and possibly more effective.

The air flowing through the axial ducts 52 and into the plenum chamber 50 keeps the injector cool and due to the action of the openings 58 which act as swirl vanes, the air leaving the cap is in the form of six swirling streams of high velocity air which sweep over the face 60 of the cap and create a flow regime which actively discourages any carbon particles which may be formed, from adhering to the fuel injector particularly to the face 60 of the end cap. The swirling air issuing frorn the openings 58 also assists in the mixing of the fuel and air.

Claims

1. A gas turbine engine fuel injector having a fuel duct terminating in a plurality of radially directed fuel outlets, a housing having an open upstream end and a closed downstream end, and a plurality of radially directed ducts, one of the fuel outlets being alinged with a respective one of said radial fuel outlets, the housing being arranged to receive a flow of compressed air, and a flow of compressed air and fuel being arranged to flow through each one of said radial ducts, a ring of swirler vanes disposed around the housing upstream of the radial ducts, through which compressed air is arranged to flow and impinge upon the flow of fuel and air leaving the radial ducts, the housing having an end cap at the downstream end thereof which with the housing defines a plenum chamber arranged to receive a flow of compressed air through a plurality of axial ducts, the end cap having a plurality of openings for the outlet of air from the plenum chamber.

2. Afuel injector as claimed in claim 1 in which the openings in the end cap are radial slots, the axis of each slot being at an acute angle to the downstream face of the end cap.

3. Afuel injector as claimed in claim 1 in which the openings in the end cap are groups of inclined holes the axis of each holes being at an acute angle to the downstream face of the end cap.

4. A fuel injector as claimed in any one of the preceding claims in which the axial duct and radial ducts are alternately arranged around the housing.

5. Afuel injector as claimed in claim 4 in which the axial ducts are in communication with an annular chamber which is supplied with a flow of compres sed air through a number of axial inlets greater in number than the number of axial ducts.

6. A gas turbine fuel injector constructed and arranged for use and operation substantially as herein described and with reference to the accompanying drawings.

7. A gas turbine engine including at least one fuel injector as claimed in any one of the preceding claims.