US2438858A - Liquid-fuel combustion chamber - Google Patents

Description

March 30, 1948. w. H. uNbsEY m'AL LIQUID-FUEL COMBUSTION CHAMBER Filed July 20, 1943 Patented Mar. so, 1948 LIQUID-FUEL COMBUSTION CHAMBER William Henry Lindsey and Sidney Allen, Coventry, England, assignors to Armstrong Siddeley Motors Limited, Coventry, England Application July 20, 194:. serial No. 495,523 In Great Britain September 11, 1942 4 cam. (01. Isa-28) This invention relates to a liquid-fuel combustion apparatus, and particularly to a heavy-fuel combustion apparatus for an internal-combustion turbine plant, though the use of the combustion apparatus is in no sense restricted thereto.

Our main object is to provide means whereby to ensure rapid and very complete combustion.

A further object is to provide a combustioninitiating chamber, in which injected fuel and primary air are mixed, which is pre-heated by a burning mixture. Preferably, the arrangement is such that the mixture of injected fuel and primary air emerges from the combustion-initiating chamber through a sharp-edged orifice (so as to provide turbulence) into an enclosure whence it is returned externally to heat the combustion-initiating chamber before being mixed with the diluent air.

A further object is to provide a liquid-fuel combustion apparatus which incorporates at least two combustion-initiating chambers acting in series into each of which a portion of the fuel and primary air is supplied, the arrangement being such that the burning mixture from the first chamber serves for vapourizing the fuel and heating the air of the next chamber. Preferably, the mixture from the first and/or the second chamber emerges through a sharp-edged orifice.

In any of these constructions the combustioninitiating chamber may be cylindrical, the primary air being led tangentially thereto.

By raising the temperature of the combustioninitiating chamber (or of the second combustioninitiating chamber, as the case may be) before ignition takes" place, the speed of chemical combination of the fuel and air (which varies approximately as the square of the absolute temperature) is increased. Furthermore, the effect of the fuel being vapourized in suspension in the air assists in ensuring efficient mixing of the fuel and air, whilst the increased vigour of the chemical action provides increased turbulence thereby increasing the chance of each particle of fuel finding the necessary oxygen. By this means very complete combustion can be obtained with a relatively-small combustion apparatus.

For a better understanding of these and other objects and advantages of the invention attention should be directed to the following description in which reference is made to the accompanying diagrammatic drawings, wherein:

Figure 1 is a fragmentary longitudinal section through one form of combustion apparatus according to the invention, the section being mainly on the line 1-1 of Figure 2;

Figure 2 is a cross-section taken mainly on the line 11-11 of Figure 1; and

Fig. 2a is a perspective detail of the combustion-initiating chamber.

In the construction of Figures 1 and 2, as applied to a combustion apparatus for an internal-combustion turbine plant, the compressed air is led along a tube ll axially within which is disposed a thimble-like member i2 containing in its interior, approximately'mid-way of its length, a combustion-initiating chamber. This is conveniently a hollow cylinder l3, coaxial with the thimble-like member l2, provided with two tangential inlets I4, I for primary air collected from the main air stream passing between the thimble-like member and the tube I I, and the fuel may be injected into the inlets, as shown at I5, IE, or into the interior of the combustion-initiating chamber. An apertured cylinder 2| is arranged centrally in the hollow cylinder 13, being conveniently carried by the wall 25. On its face adjacent the closed end ii of the thimble-like member, the closed end l6 being towards the flow of compressed air, the cylinder I3 is provided with a sharp-edged orifice I! through which the burning fuel and primaryair passes, turning round in the space i8 between the combustioninitiating chamber and the closed end ii of the thimble-like member to impinge against and pass round the sides of the combustion-initiating chamber, thereby to pre-heat it, before emerging from the open end I! of the thimble-like member to join the diluent air, which is in the form of an annulus surrounding the thimble-like member. Openings 2!] may be provided in the thimble-like member to admit additional air from tube H for completing combustion.

We have found that the forward speed of the gases at the center of the vortex in the combustion-initiating chamber i3 is low, as a result of which the flame base tends to rest on the base wall 25, thereby causing over-heating. The object of providing the perforated tube 24 is to destroy the vorticity of the gases within it, thus aesaeea 8 lined fairing ma be provided in a manner well understood.

In this way the self-heated combustion-initiat ing chamber serves for pre-heating the swirling primary air and injected fuel and for vapourizing the latter, and the sharp-edged exit orifice l7 serves for introducing turbulence to increase the mixing of the fuel and air, so that very rapid and complete combustion is obtained. 7

Obviously, if desired, a second combustioninitiating chamber could be mounted further along the combustion apparatus, and obviously, in practice, use may be made or several such combustion apparatus, for example, a dozen, acting in parallel.

In this way we preheat the subsequent combustion-initiating chamber or chambers so as to raise the fuel and air mixture to a high temperature before ignition takes place, thereby ensuring rapid and very complete combustion.

What we claim as our invention and desire to secure by Letters Patent of the United States is:

1. A liquid fuel combustion apparatus for an internal combustion power plant including a tube for supplying compressed air to the apparatus, a cylindrical thimble-like member positioned coaxially within said tube with its closed end directed towards the flow of compressed air through said tube, a cylindrical drum-like part of heat conductive material constituting a combustion-initiating chamber positioned coaxially within and spaced from the cylindrical wall of said thimble-like member, means for supplying primary air from said tube to said combustioninitiating chamber, and means for supplying liquid fuel under pressure to said chamber, said combustion-initiating chamber having, in its end wall facing the closed end of said thimblelike member, an aperture concentric with the axis of said chamber providing a sharp-edged outlet orifice into said member for producing turbulence in the burning mixture to facilitate its complete combustion within said member, and the closed end of said member deflecting, in

counter-flow, the burning mixture externally around the combustion-initiating chamber to heat the same.

2. A liquid fuel combustion apparatus according to claim 1 in which the combustion-initinting chamber has tangentially disposed inlets for leading the primary air thereinto.

8. A liquid fuel combustion apparatus, according to claim 1, having in the combustion-initiating chamber a coaxial perforated tube supported from the wall which is opposite said orifice.

4. A liquid fuel combustion apparatus, according to claim 1, having in the combustioninitiating chamber a coaxial perforated tube supported from the wall which is opposite said orifice, said tube being of substantially the same axial length as said combustion-initiating chamber and of smaller diameter than said orifice.

WILLIAM HENRY LINDSEY. SIDNEY ALLEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 944,975 Sodeau Dec. 28, 1909 r 1,314,175 Wells et a1. Aug. 26, 1919 1,405,482 Bostedo Feb. '7, 1922 1,629,921 Mansfield May 24, 1927 1,666,367 Clausing Apr. 17, 1928 1,697,687 Lockwood Jan. 1, 1929' 1,755,949 Clarkson Apr. 22, 1930 2,078,957 Lysholm May 4, 1937 2,085,800 Goddard July 6, 1937 2,164,954 Stephens July 4, 1939 2,181,186 Jackson Nov. 28, 1939 2,195,025 Couzinet Mar. 26, 1940 2,227,666 Noack Jan. 7, 1941 2,249,489 Noack July 15, 1941 2,262,195 Noack Nov. 11, 1941 2,362,571 McCollum- Nov. 14, 1944

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