JPS58193025A - Fuel injector for gas turbine engine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injector for a gas turbine engine and is an improvement on a fuel injector of the type described in British Patent No. 1,427,146.

The British patent specification includes a central duct for receiving the flow of fuel and air, and an adjacent downstream end of the duct which together with the ends of the duct form a radially oriented annular outlet for the fuel-air mixture from the tubes. A fuel injector is described having a deflection member in position and a shroud around the central duct forming an annular outer duct through which air is discharged from the central duct upstream of an annular outlet. This type of fuel injector, together with the combustion chamber in which it is placed, is intended to produce two adjacent and opposite toroidal vortices, the upstream vortex being the fuel vortex and the downstream vortex being the fuel vortex. The vortex should be fuel lean.

To minimize NOx (nitrogen oxide) emissions, the air-to-fuel ratio in the upstream vortex should be about 1,000 and that in the downstream vortex should be about 1,000.

In practice, it has been found that the air/fuel ratios of the two vortices are not always as required. The upstream vortices tend to have low fuel excess and the downstream vortices tend to have low fuel leanness, indicating that there is fuel movement between the two vortices and unequal distribution of fuel from the fuel injectors to the vortices. It shows.

The intention of the arrangement shown in the above-mentioned GB 1427146 is that all the fuel from the injector flows into the upstream vortex, and the downstream vortex carries unburned and/or partially burned fuel into the upstream vortex. Karauke was to enter. Nowadays, some of the fuel from the fuel injector intended to enter the upstream vortex flows directly into the downstream vortex, so that the mixing ratio of the upstream vortex is thin and the mixing ratio of the downstream vortex is It is thought that it will become darker. Any misdistribution will adversely affect NOx emissions, combustion efficiency and the lean fuel ratio at which combustion stops. The present invention allows for more precise control of the air-fuel ratio within the two vortices.
This is an improved version of the fuel injector of the type disclosed in No.S.

It has also been found that the deflection elements at the ends of the central duct are of an unnecessarily complex and expensive type.

The invention therefore also aims to provide a simpler and cheaper type of deflection element.

The present invention is a gas turbine engine fuel injector for injecting air and fuel into a combustion chamber, comprising: a central duct having open upstream and downstream ends; a deflection member near the downstream end of the central duct; a shroud member partially surrounding the central duct to form an annular duct, the deflection member and the downstream end jointly forming an annular outwardly directed outlet; The duct is adapted to receive air from the engine compressor, in which the fuel injector is located, and the central duct is adapted to also receive air from the fuel nozzle and is discharged. In order to inject virtually all of the air/fuel mixture exiting the outlet into the upstream annular vortex within the combustion chamber, the outwardly directed annular outlet constricts over its entire circumference and its terminus points outward and upstream. The fuel injector is characterized in that a second downstream annular-shaped vortex is present in the combustion chamber adjacent to the upstream vortex and oppositely oriented to the upstream vortex.

The fuel injector of the present invention also has a lip at the downstream end of the central duct, which lip together with the deflection member forms an outlet;
It can also serve to divert air from the annular duct to the air/fuel mixture leaving the outlet.

The central duct may also have a restlifter ring at its upstream end to reduce the momentum of the air-fuel mixture therein.

When the fuel injector is placed in a combustion chamber where it is desirable to have an inlet in the wall for providing air flow to both the upstream and downstream vortices, the fuel outlet is connected to the air inlet to the upstream vortex. Directed to higher upstream locations.

Referring first to Figures 1 and 2, British Patent No. 1427
The fuel injector of the No. 146 specification will be explained.

The fuel injector 10 includes a central duct 12 arranged to receive fuel from the nozzle 14 and air from the engine compressor, a deflection member 16, and an outer shroud 118 that forms an annular air passageway 20 with the central duct. , has.

The downstream end of the central duct forms, together with the deflection member 16, a radially directed outlet 22 which directs the air/fuel mixture into the combustion chamber 24 where the fuel injector is present.

The air/fuel mixture exits radially and generates an upstream annular vortex 26 which is ignited by an igniter (not shown) K, with a portion flowing from the injector 16 and a portion flowing through the opening 60. This combusting air/fuel mixture merges into a downstream vortex 28 generated by the diluted air entering the combustion chamber from the combustion chamber.

As shown in more detail in FIG. 2, the downstream end of the duct 12 has an inwardly directed lip filter 2 to prevent fuel droplets sticking to the duct wall from flowing through the airflow within the duct. The deflection member 16 has an upstream facing surface 34 which, together with the inner surface of the duct 12, forms a smooth convergent passage for the air-fuel mixture. , the flow is bent outwards to enter the annular convergent section 66 and then further bent to the outlet 2.
Go outside from 2. Convergent portion 66 includes portions A and B that continuously decrease in cross-sectional area. After these sections, the flow is separated and smoothly converges into an annular opening 22 from which the air-fuel mixture flows substantially radially relative to the fore-and-aft direction of the engine and fuel injector. is discharged. The shape of the outer portion of the deflection member 16 is such that it effectively imparts an upstream and radially outward flow component to the impinging air-fuel mixture, and directs other flows, such as the annular duct 20
The downstream momentum of the flow from the outlet jointly directs the flow from the outlet 22 in a substantially radial direction.

The outlet 22 is defined by the lip 68 of the duct 12 and is an annular opening with a surface lying substantially perpendicular to the longitudinal axis of the engine. This location of the outlet 22 helps ensure that the flow exiting the fuel injector is radially emitted.

It will be seen that great emphasis is placed on the location of the outlet 22, the relatively complex converging passageway leading to the outlet 22, and the need for purely radial evacuation of the air-fuel mixture. . Experience has shown that the arrangement shown in FIGS. 1 and 2 does not provide completely satisfactory combustion conditions. In particular, the air-fuel ratio decreases in the upstream vortex, and the fuel richness decreases, while the downstream vortex decreases the fuel leanness. Also, the inner surface of the deflection member 16 and the end of the central duct 12 defining the outlet passageway would be unnecessarily difficult and expensive to manufacture.

Referring now to FIGS. 3-6, the present invention will now be described in detail. A fuel injector 110 is disposed in a combustion chamber 124 of a gas turbine engine 100.

The fuel injector facilitates fabrication of the deflection member 116 as compared to the difficult and expensive deflection member 16 having a central duct 112, fuel nozzle 114, deflection member 116, outer shroud 118, and annular duct 120; In order to improve rather than detract from performance, the deflection member 116
It is mainly formed by multiple flat plate surfaces with smoothly polished joints.

In particular, the shape of the convergent passage leading to the opening 122 is formed by two flat circular surfaces 12 that form an obtuse angle with each other and have smooth abutments.
2α and 122h. Similarly, the outer surface of the deflection member consists of flat surfaces 122C and 122d, both of which facilitate fabrication.

The central duct has a lip 140 at its downstream end so that the deflection member 116 forms an outlet 122 facing outwardly in the upstream direction. The lip 140 also serves to deflect the air from the annular duct 120 away from the air/fuel mixture exiting the opening 122 and into the upstream vortex 126 .

A rest lifter ring 142 is disposed at the upstream end of the central duct to reduce the momentum of the air-fuel mixture passing through the central duct so that virtually all of the air-fuel mixture, particularly the fuel component, is directed directly into the upstream vortex flow. It helps to flow into 126. In the wall of the combustion chamber 124 there is an air population 130 corresponding to the inlet 30 but of a different type, the details of which are shown in FIG.

Air inlet 160 takes the form of a cooling ring and has a series of upstream facing holes 130a and a set of downstream facing holes 160h. A series of central holes 130C may also be provided for channeling air to cool the inwardly protruding portions of the cooling ring. An important feature of the arrangement of fuel injector 110 and combustion chamber 1 and 4 is the arrangement of outlet 122 and air inlet 130. For this arrangement to work properly, the fuel injector outlet should be oriented at a point upstream of the air inlet hole 160α. During operation, the fuel injector and combustion chamber receive airflow from the compressor of engine 100, and the fuel injector also receives heating charge from fuel nozzle 114. The air-fuel mixture is discharged through the opening 122 in an outward upstream direction into an upstream vortex 126 . The air/heat mixture, in particular the fuel component, enters directly into this vortex, so that the fuel is received from the upstream vortex into the downstream vortex in unburned or partially burned form. The upstream vortex also receives air from the annular duct) 120 and the inlet 130α,
This air helps hold the vortex together.

The lip 140 acts as a deflector for the air leaving the annular duct 120, stabilizing this airflow and encouraging it to enter the upstream vortex, which also directs the flow toward the opening 122.
This prevents the air/fuel mixture from colliding with the air and fuel mixture from causing harmful effects. The rest lifter ring 142 reduces the momentum of the air/fuel mixture in the central duct and
The purely radial momentum of the mixture leaving the vortex is reduced, forcing substantially all of the air-fuel mixture to enter the upstream vortex 126. This arrangement creates two axially disposed opposite vortices, with the upstream vortex air and
The fuel ratio indicates the fuel richness of the handle, and the downstream vortex indicates the fuel leanness of the sesho. The effect of this arrangement is to reduce NoX emissions by an order of η at a total air to fuel ratio of 55/1 compared to the arrangement shown in the aforementioned GB 1427146. It also improves combustion efficiency at idle (slow speed) by 6%, and increases the lean air-fuel ratio at which combustion stops by about 6 times.

It appears that the majority of the improvement is achieved by changing the shape of the deflector member, while the remaining improvement is shared approximately equally between the lip 140 and the rest trifter 142.

[Brief explanation of drawings]

1 is a diagram of the fuel injector and combustion chamber shown in the British Patent No. 1427146; FIG. 2 is a detailed view of the combustion chamber and fuel injector shown in FIG. 1; 4 is a schematic illustration of a gas turbine engine incorporating one type of fuel injector according to the present invention; FIG.
FIG. 5 is an enlarged elevational view of the combustion Y and fuel injector portions similar to FIG. 1; FIG. 5 is an enlarged elevational view of the fuel injector shown in FIG. 4;
FIG. 6 is a detailed view of the air intake ring of the combustion chamber shown in FIG. 4; 112...Central duct 114...Fuel nozzle 116...Deflection member 118...Shroud 9 member

Claims (4)

[Claims] (1) A gas turbine engine fuel injector arranged to inject air and fuel into a combustion chamber, including a central duct having open upstream and downstream ends, and a central duct located adjacent to the downstream end of the central duct. a deflection member and a shroud member at least partially surrounding said central duct to form an annular duct, said deflection member and said downstream end jointly forming an annular outwardly directed outlet; form,
the central duct and the annular duct are arranged to receive airflow from an engine compressor in which a fuel injector is disposed, the central duct also receiving fuel flow from a fuel nozzle; the outwardly directed annular outlet is arranged such that the outwardly directed annular outlet constricts over its entire circumference and its terminal end injects substantially all of the air/fuel mixture exiting the outlet into an upstream annular vortex of the combustion chamber; said outlet facing outward and upstream, and a second downstream annular vortex is present within the combustion chamber adjacent to and opposite said upstream vortex; Injector. (2) an outwardly extending lip is provided at the end of the central duct, the lip and the end of the deflection member defining the outlet; 2. The fuel injector according to claim 1, further having the function of deflecting. (3) The central duct has a flow restrictor adjacent to its upstream end to reduce the momentum of the air/fuel mixture within the central duct. Section fuel injector. (4) The surfaces of the deflection member against which the air/fuel mixture from the central duct collides have at least two flat surfaces that are inclined at an angle greater than 90° to each other and that smooth the interface. A fuel injector according to claim 1, characterized in that the fuel injector has: