JPS6038518A - Fuel burner 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 burner for a gas turbine engine. The invention is disclosed in British Patent No. 1427146/
It evolved from the J fuel injector.

The fuel burner of the type of the present invention is a reflex air spray burner (reflective air spray burner> (RAB)).
a hollow cylindrical burner tube, a deflection member centrally positioned by several radially arranged vanes downstream of the burner tube, and an outer side which together with the burner tube forms an annular air passage. Includes a shroud member. The downstream end a5 of the burner tube and the deflection member define an annular radial convergent outlet for the fuel-air mixture from the burner tube.

This arrangement creates two opposing donut-shaped vortices of the fuel-air mixture within each engine combustion chamber, with the upstream vortex also being fed by the annular air shroud and the downstream vortex flowing through the combustion chamber wall. Air is also supplied through the opening. This arrangement ensures nearly perfect mixing of aviation fuel and air within the burner tubes, and the dual swirl environment has been found to provide considerable combustion stability over the full range of engine operating complements. It has also been found that because this type of burner does not protrude into the combustion chamber to stabilize combustion, the burner does not break down quickly and has a long useful life. This type of burner is also effective in reducing the production of undesirable emissions such as IM carbon (Co), nitrogen oxides (NOX), unburned hydrocarbons (UHC), and smoke.

Gas generators for aviation gas turbine engines are often applied to power industrial and marine applications, and in such cases they may contain fuels other than aviation kerosene, such as gaseous fuels and diesel oil. It is desirable for the engine to operate with relatively heavy oil.

Difficulties in ignition and spread of ignition have been found when RAS type burners are operated with diesel oil, and in order to overcome these difficulties, an auxiliary fuel injector operated with diesel oil is used to initiate the combustion process. I had to. The disadvantages of this arrangement are obvious. This problem arises because fuel flowing into the burner tube collects and flows at the junction of the deflection member and the support vane. The generated flow, the number of which depends on the number of vanes, subsequently flows straight into the combustion chamber through the convergent outlet, causing atomization and/or mixing of the fuel between the fuel and the air. The drawback of this very rich fuel is that it is difficult, if not impossible, and requires auxiliary injectors.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fuel barb of the RAB type that can prevent fuels such as diesel fuel from converging into several discrete streams and eliminates the need for auxiliary fuel injectors. shall be.

Accordingly, the present invention provides a fuel discharge tube, a burner tube arranged to receive a fuel flow from the fuel discharge tube and air at an upstream end, and a burner tube supported near its downstream end from the burner tube. a deflection member defining an annular outlet with a downstream end of the tube; and an annular air duct surrounding the burner tube arranged to receive air at an upstream end and discharge air from a downstream end upstream of the annular outlet. and the deflection member includes a flat impingement surface perpendicular to the burner longitudinal axis, and the fuel from the fuel discharge pipe is arranged to impinge on the impingement surface, and is atomized by the air. A burner is provided, the deflection member having a deflection surface extending radially beyond the boundaries of the burner tube for deflecting fuel in a generally radial direction.

The deflection member can be mounted at the downstream end of the burner tube by several relatively thin-walled garments so as not to impede the flow of the atomized fuel and air mixture.

Preferably, the burner tube and impact surface are cylindrical and the deflection surface is circular.

The arrangement according to the invention provides excellent atomization and placement of a well-mixed air and fuel combination, facilitates ignition, provides good spread of ignition to the surroundings, and eliminates the need for auxiliary fuel injectors. It disappears.

The present invention will be described in more detail below with reference to the accompanying drawings.

Referring to the drawings, a gas turbine engine 10 has an axial air intake 12, a compressor means 14, a combustion furnace arrangement 16, a turbine means 18, and an exhaust nozzle 20.

The combustion system includes a plurality of separate tubular combustion chambers 22 spaced circumferentially about the engine axis in what is referred to as a "tube-original" or "can-original" configuration.

The upstream end of one of the combustion chambers 22 and the
27146) is shown in FIG.
Shown in more detail. The burner 24 has a burner tube 26
, a deflecting member 28 having an axis 30 supported from the burner tube 26 by several equally spaced vanes 32, and with the burner tube defining an annular air passage 36 with an air inlet 3 at the upstream end.
8 also includes an air shroud 34 having an air outlet 40 at its downstream end. Each vane 32 is connected to a fuel injector 44.
The interior of the burner tube is divided into several sector-shaped passages that receive fuel flow from one of the nozzles 42 of the burner tube.

The deflection member 28 defines a convergent annular outlet 48 for the fuel-air mixture with the downstream end of the burner tube.

The fuel and air exit the outlet 48 in a generally homogeneous mixture, forming two opposing toroidal vortices 50,52, the upstream vortex 50 also being supplied with air from the outlet 40. , a downstream swirl 52 receives air through an opening 54 in the wall of the combustion chamber 22 .

Fuel tends to collect at the junction of vanes 32 and shaft 30 to create separate flows. The fuel does not mix well with the air from the engine compressor 14 in the burner tubes and the vanes 32
exits outlet 48 in a number of streams equal to the number of . The fuel-air mixture in the area of the plane containing outlet 48 is therefore very lean or rich and difficult, if not impossible, to ignite under engine starting conditions. This problem is exacerbated by fewer vanes, reducing the number of fuel streams and increasing their spacing.

One solution is to use an auxiliary fuel injector that operates on diesel fuel, ignites this fuel with a conventional spark plug, and allows combustion of the auxiliary fuel to initiate combustion of diesel fuel from burner 24.

A disadvantage of this arrangement is that an auxiliary fuel burner and another supply system for diesel fuel must be provided, and the auxiliary fuel burner is susceptible to overheating and/or becoming coated with carbon deposits.

Referring to FIGS. 3 and 4, in which elements similar to those shown in previous figures are given the same reference numerals, a deflection member is attached to the downstream end of the burner tube by a plurality of webs 28a. These webs, preferably three or four equally spaced in number, have a relatively thin cross section so as not to impede the flow of the fuel/air mixture from the burner.

The deflection member includes a circular, flat impingement surface 28b arranged perpendicular to the longitudinal axis of the burner, and a deflection surface 28C extending radially beyond the circumference of the burner tube 26.

The fuel discharge pipe has a single outlet 4 at the inlet to the burner pipe.
2, discharging a condensed jet of high pressure liquid fuel that impinges on surface 28b. The collision atomizes the fuel and spreads it evenly in the radial direction. The atomized fuel is captured in the high velocity airflow from the burner tubes, mixing the fuel and air as they exit the combustion chamber 22. The deflection surface 28C and the gap 48, ie the shape of the deflection surface and/or the size of the annular gap, determine the direction of the air mixture flow.

By using the burners shown in Figures 3 and 4, the diesel fuel is sufficiently atomized and mixed with air to be passed into the combustion chamber where it can be ignited without difficulty using a conventional spark plug. It turns out that it can be done. It also provides excellent spread ignition, ie the ability for ignition in one combustion chamber to be transmitted to another combustion chamber via a connecting pipe.

It has also been found that the combustion pattern factor J, that is, the degree of thermal variation in the vertical and horizontal directions of the exit annular zone of the combustion system, has been significantly improved.

Due to the radial extension of the deflection element beyond the surface of the burner tube, the fuel-air mixture is precisely located in the desired area of the combustion zone. This precise placement can be aided by the use of a lip 56 and a rest lifter ring 58, both of which are described in another British patent (No. 82116).
No. 81). Lip 56 is a deflector of the air leaving air passage 36 and helps stabilize this flow into the upstream vortex 50 so that this air flow is not detrimental to the air-fuel mixture exiting outlet 48. Prevent collisions to the extent that they occur.

The rest lifter ring 58 reduces the movement of the mixture within the burner tube, creating a purely radial movement of the mixture m, which helps to direct substantially all of the mixture into the upstream vortex 50.

The burner configuration shown in Figures 3d) and 4 properly achieves ignition and acceleration to slow speed, improving start a3 and slow speed efficiency. Engine fueling above slow speed is achieved in one of two ways.

As shown in FIG. 4, the main fuel can be injected from the fuel injector 44 into the burner @2G in the form of a spray cone 60. The atomized fuel is captured by the air flowing through the tube 26 and the air-fuel mixture is forced to exit the burner through the annular outlet 48 in a generally radial direction by the deflection surface 28C.

In another arrangement, shown in FIG. 5, the main fuel exits the injector 44 in the form of a high pressure liquid fuel annulus 62;
The surface 28b is similar to the primary (9 (3-movement) fuel jet I-).
collide with The main fuel is atomized by impact, and the atomized fuel is evenly distributed radially.

The air flowing inside the burner tube is combined with the atomized fuel, and the fuel-air mixture is formed in the direction f due to the direction of the deflection surface 28C1, the direction of the annular gap 48, and the influence of the air flow from the annular air passage 36.
= J number is pulled and sent into the combustion chamber.

- The primary fuel and main fuel flows can be introduced together when engine operating speed is reached and running at that speed, or when the engine is started and a slow speed is reached, the primary fuel is stopped and the engine is It is also possible to operate on fuel flow only.

It is important that the high-pressure fuel jet remains cohesive until it hits the surface 281. This is achieved by choosing a suitable jet length/diameter ratio. For example, it has been found that an L/D ratio of 6 is good.

[Brief explanation of drawings]

FIG. 1 is an external view of a gas turbine engine having a combustion device including a fuel burner according to the present invention, and FIG.
1427146; FIG. 3 is a sectional view of the RAB type burner according to the invention, which is placed inside the can of a can/annular combustor; and FIG. 4 is the burner of FIG. 3. FIG. 5 is a sectional view of a modified version of the burner shown in FIG. 22... Combustion chamber 24... Burner patent applicant Rolls-Royce Limited (5 others)

Claims (5)

[Claims] (1) a fuel discharge tube and a burner tube arranged to receive fuel flow from the fuel tube and air from an upstream end;
a deflection member supported from the burner tube near its downstream end and defining an annular outlet with the burner tube; and a deflection member arranged to receive air at the upstream end and discharge air from the downstream end upstream of the annular outlet. an annular air duct surrounding the burner tube, the deflection member including a flat impingement surface perpendicular to the burner longitudinal axis, the fuel from the fuel discharge tube being arranged to impinge on the impingement surface; , the deflection member having a deflection surface extending radially beyond the boundaries of the burner tube for deflecting air and atomized fuel in a generally radial direction. Fuel burner for engines. 2. The burner of claim M1, wherein the deflection member is attached to the burner tube by several equally spaced axially extending webs. (3) The burner according to claim 1, wherein the collision surface is circular and the deflection surface is annular. (4) the fuel discharge pipe has two fuel outlets, the central outlet discharges a high-pressure agglomerated jet of primary (starting) liquid fuel that impinges on the impingement surface, and the outer outlet atomizes; 2. A burner as claimed in claim 1, discharging a conical main fuel into the burner tube. (5) The fuel discharge pipe has two fuel outlets, the central outlet discharges a high-pressure flocculation jet of primary liquid fuel, the outer outlet discharges an annular high-pressure jet of main fuel, and the primary and 2. A burner as claimed in claim 1, wherein the main fuel jets are arranged to impinge together on the impingement surface.