Combustion Chambers For Gas Turbine Engines

Abstract

A combustion chamber for a gas turbine engine comprises a flame tube surrounded by an air passage, fuel sprayer(s) at one end of the flame tube and a combustion gas outlet at the end. A number of sets of apertures are formed by corrugated portions of the wall to cause air entering the flame tube to flow along the wall thereof. Baffles project from the wall and are disposed in the flow path of the air flowing along the wall. Projections extend from the baffles substantially parallel to the wall and towards the apertures formed by the respective corrugated portions.

Description

This invention relates to combustion chambers for gas turbine engines.

According to the present invention, there is provided a combustion chamber for a gas turbine engine, comprising a flame tube, an air supply passage separated from the flame tube by a wall thereof [or of the flame tube] a plurality of apertures in the wall providing communication between the air supply passage and the interior of the flame tube some of the apertures being adapted to cause a flow of air along the wall within the flame tube baffles projecting from the wall within the flame tube for deflecting air passed, in use, along the wall from at least some of the said apertures, and projections spaced from the wall and extending from the baffles in a direction transverse to the direction of extent of the baffles whereby circulation of gas, in use, is established and maintained in the desired flow pattern.

Preferably, the said baffles comprise strips which are attached to the wall within the flame tube at one side thereof and are provided with a series of spaced recesses at the other side thereof and the projections extend from the baffles at the bases of the recesses in a direction upstream of the respective baffles relative to the air whose circulation is promoted thereby.

Most advantageously, some other of the apertures are adapted to cause a flow of air along the wall within the flame tube by being provided with baffles which extend substantially parallel to the wall in the vicinity of the apertures and some of the apertures are formed in portions of the wall which extend transversely to portions on either side of the wall so that air is introduced transversely with respect to said portions. Advantageously, the baffles carrying the projections are disposed adjacent the last mentioned apertures with the projections extending towards said apertures.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings in which:

FIG. 1 is a sectional view through part of a combustion chamber according to the present invention, and

FIG. 2 is a section on the line A--A of FIG. 1.

Referring to the drawing, the combustion chamber comprises an annular flame tube 1 surrounded by an annular air supply passage 2 which is separated from the flame tube 1 by a generally toroidal wall 3 of the flame tube 1.

An annular air inlet 4 serves to supply air to the air supply passage 2 and a series of fuel injectors 5 serve to inject fuel into the flame tube 1 together with primary air from the air supply passage 2. The flame tube 1 is provided with an annular exhaust outlet 6.

The wall 3 is of fabricated construction and has formed therein series of apertures 7, 8 and 9 which provide communication between the air supply passage 2 and the interior of the flame tube. The series of apertures 7 are baffled by baffles 10 so that air is introduced along the inside of the wall 3 to enhance cooling of the wall 3. The series of apertures 8 are similarly baffled by means of baffles 11 to provide flow along the wall 3, but the baffles 11 direct flow of air in a direction away from the exhaust outlet 6 and towards the fuel injectors 5. The series of apertures 9 are formed by a pair of annular corrugated strips 12 (see FIG. 2) disposed between adjacent, overlapping portions of the wall 3, the corrugated strips 12 forming, in effect, a portion of the wall 3 which extends transversely to portions of the wall on either side thereof. In this manner, the series of apertures 9 are disposed to admit air into the flame tube 1 along the wall 3. It will be seen from FIG. 1 that the series of apertures 9 formed in the outer portion of wall 3 serve to direct air towards the fuel injectors 5 whilst the series of apertures 9 in the inner portion of the wall 3 serve to direct air from the fuel injectors 5. At a location which is downstream of the series of apertures 9, there are provided respective baffles 13 which project from the wall 3 internally of the flame tube 1 and are formed by annular strips attached at one of their sides to the wall 3 whilst the other sides thereof which extend into the flame tube 1 are provided with a series of spaced recesses 14. Furthermore, a plurality of spaced projections 15 are provided on each baffle 13 to project perpendicularly therefrom at the bases of the spaced recesses 14. It will be seen from FIG. 1 that each projection 15 extends substantially parallel to the wall 3 to which its associated baffle 13 is attached and towards the series of apertures 9 associated with the baffle 13.

The baffle 13 attached to the inner portion of the wall 3 is also disposed adjacent one of the series of apertures 8 so that air entering the flame tube 1 from that series of apertures 8 is deflected not only by baffle 11 associated therewith but also by the surface of the baffle 13 remote from the projections 15. On the opposite sides of the baffle 13 to the series of apertures 9 on the outer portion of the wall 3 are provided a further series of apertures 16 providing direct communication between the air passage 2 and the flame tube 1, these series of apertures 16 being unbaffled and extending with their axes in a radial direction with respect to the axis of the flame tube 1.

It is considered that the above described combustion chamber is particularly efficient since almost all the air, some 96% is used for cooling purposes and is then deflected by the baffles 13 with projections 15, to participate in the combustion process. In contrast, in conventional arrangements about 40% of the air is introduced as cooling air which is largely confined to regions close to the flame tube wall and is not deflected to participate in the combustion process. This latter arrangement has an undesirable effect on the temperature distribution at the outlet of the combustion chamber.

Claims

I claim:

1. A combustion chamber for a gas turbine engine, comprising a flame tube, an air supply passage separated from said flame tube by a wall thereof, means defining a plurality of apertures in said wall providing communication between said air supply passage and the interior of said flame tube, each of said apertures being adapted to cause a flow of air along said wall within said flame tube, baffles projecting from said wall within said flame tube for deflecting air passed, in use, along said wall from at least some of said apertures, and projections spaced from said wall and extending from said baffles in a direction transverse to the direction of extent of said baffles whereby circulation of gas, in use, is established and maintained in the desired flow pattern.

2. The combustion chamber according to claim 1, wherein said baffles comprise strips each of which is attached at one side thereof to said wall within said flame tube and is provided with a series of spaced recesses at the other side thereof, and said projections extend from said baffles at the bases of said recesses in a direction upstream of the respective baffles relative to the air whose circulation is promoted thereby.

3. The combustion chamber according to claim 1, wherein some of said apertures are adapted to cause a flow of air along said wall within said flame tube by being provided with baffles which extend substantially parallel to said wall in the vicinity of said apertures and some of said apertures are formed in portions of said wall which extend transversely to wall portions on either side thereof so that air is introduced along the last-mentioned portions.

4. The combustion chamber according to claim 3, wherein said baffles carrying said projections are disposed adjacent said apertures formed in the transversely extending wall portions, said projections extending towards the last-mentioned apertures.