US2941364A - Igniter chamber for a gas turbine engine - Google Patents

Description

v art" June 21, 1960 M. A. STOKES 2,941,364

IGNITER CHAMBER FOR A GAS TURBINE ENGINE Filed March is, 1956 2 Sheets-Sheet 1 32 34 37 I50 I60 |7a I80 l2 22b Ma 6 i EEK! I a l9- III .'L 26 2s 2 I 20 23 '5 D I :,1'7 '4 2a I -2 FIG].

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June 21, 1960 M. A. STOKES IGNITER CHAMBER FOR A GAS TURBINEENGINE 2 Sheets-Sheet 2 Filed Marbh 15, 1956 United States Patent 2,941,364 IGNITER CHAMBER FOR A GAS TURBINE ENGINE Morris A. Stokes, Coventry, England, assignor to Armstrong Siddeley Motors Limited, Coventry, England Filed Mar. 13, 1956, Ser. No. 571,174 Claims priority, application Great Britain Apr. 5, 1955 5 Claims. (Cl. 60-39132) This invention relates to an igniter chamber for a main combustion chamber for a gas turbine engine, of the kind having a flame chamber along the outside of which diluent air is caused to flow in its passage from the compressor outlet to the turbine inlet, the flame chamber having a baifle or base plate at its upstream end which, at its downstream side, has at least one J-like, or L-like pipe into the one ends of which fuel is injected with primary air, and which also has a number of further combustion-air supply means for the flame chamber.

In a main combustion chamber comprising a circle of elongated flame chambers disposed about the axis of the combustion chamber, the said base plate is in the form of a disc, or equivalent member, at the upstream end of each flame chamber. In the annular type of main combustion chamber, the said base plate is in the form of a ring at the upstream end of the single annular flame chamher.

The main object of the invention is to provide improved means for initiating combustion in the main con1- bustion chamber. In particular, it is obviously desirable to ensure successful ignition at high altitudes, when it is necessary to re-light the main combustion chamber.

According to the invention, an igniter chamber is provided on the upstream side of the base plate, the igniter chamber having an opening at its upstream end for the supply of primary air, a batfle means, within the ignitor chamber, through which a nozzle sprays starting fuel into the primary air which has passed the said baflie means, an igniter in the vicinity of where this starting fuel is to be ignited, and at least one opening in the igniter chamber for the admission of secondary air for assisting combustion of the starting fuel before the flame passes the outletfrom the igniter chamber.

In accordance with a further feature of the invention, where, owing to the presence of a plurality of the J- pipes and further combustion-air supply means, there in radially-spaced relationship between inner and outer fine an annular outlet to aturbine rings 16, 16a,

is insuflicient space on the base plate for the independent I 1 mounting of the igniter chamber, at least one of the further combustion-air supply means is replaced by an igniter chamber, as aforesaid, and the primary and secondary air supply openings therein are such as to provide an airflow therethrough (when the engine is operating normally without the igniter chamber operating as such) which is substantially the same as that of the said further combustion-air supply means it replaces.

According to a still further feature, the primary air supply to the igniter chamber, in the vicinity of the fuel spray may be enriched with oxygen from any appropriate source.

In the accompanying drawings:

Figure 1 is a longitudinal section through part of an annular type of main combustion chamber, having a' plurality of J-like pipes and further combustion-air supply means, equipped with one form of igniter chamber according to the invention, the section being on the line 1-1 of Figure 2;

coaxial casings 11, 12, which define an annular passage for air from a compressor (not shown) to enter at 13. The flame chamber shown is defined between an inner series of coaxial, overlappingrings 14, 15, 16, 17 and 18, and an outer series ofcoaxial overlapping rings 14a, 15a, 16a, 17a and 18a. Spacer means 19 for the admission of air from the annular passage to the interior of the flame chamber, for film cooling the latter, are interposed between the adjacent ends of the inner and outer rings where they overlap, and therings 18 and 18a de- (not shown). The 17 and 17a are shown provided withopenings 20 for the admission of cooling air for the main combustion.

Therings 14, 14a sealingly support, by its inner and outer peripheries, anannular base plate 21, and the latter supports a plurality of J-like pipes 22 which extend in the downstream direction. The open upstream ends 22a of these pipes extend through the baflle where they receive primary air for the main combustion and also receive the main fuel supply through pipes of which one is indicated at 2-3 in Figure 1; while the downstream ends 22b of these pipes are directed upstream to face the downstream side of the baflle.

In appropriate positions between the upstream ends: 22a the baflle supports a plurality of secondary air supply means 24 which conveniently take the form of thimbles;

withslits 24a at their downstream ends, and it is in place them in the case of an annular combustion chamber (although, due to a part of the battle being omitted from Figures 1 and 2, only one is shown) so that ignition can still be ensured evenif one igniter chamber shouldfor any reason fail.

The igniter chamber is indicated at 25 and it extends upstream from thebase plate 21. The chamber has acentral opening 26 for primary air, and downstream of the opening is a bafile means 27 around which the primary air must flow. Acylindrical baflie 28 surrounds thebaflle 27 with an annular clearance which provides the incoming primary air with a desirable pressure drop, and thebaflle 28 has a radial flange which is held to thelip 29 surrounding the opening 26 by a circle ofrivets 30 whose other ends support thebaffle 27.

In the construction of igniter chamber shown in Figures 3 and 4, the starting fuel is sprayed downstream from anozzle 31, at the delivery end of asupply pipe 32, through a central, sharp-edged orifice 33 in thebaflle 27 to the vicinity of ahigh energy igniter 34. The latter is arranged in a position in the igniter chamber where the primary air is recirculating behind thebaffle 27, and downstream of the igniter the igniter chamber has open--ings 35 for the admission of secondary air.

By thus constructing the igniter chamber, it producesa flame from itsoutlet 36, which is fast in the hole of can be sprayed into the flame chamber to facilitate and speed up ignition at those parts where there is no igniteri.e., to pass on the igniting flame from theoutlet 36 of the igniter chamber with a minimum of delay.

As previously mentioned, ignition can be ensured in an even more satisfactory manner when a supply of oxygen is available to supplement the supply of primary air to the igniter chamber. Such a construction is shown in Figure 5 where the startingfuel supply pipe 32 is brought along a coaxially-arranged,oxygen supply tube 38 terminating at its downstream end with a spray nozzie. This nozzle is an annular one existing between the periphery of thefuel spray nozzle 31 and a lateral opening at the downstream end of thetube 38, and the latter has aunion 39 for the oxygen supply at its upstream end. As shown. the union is part of afitting 40 which is spigotally fitted to thetube 38 and also supports thefuel supply pipe 32, being provided with aunion 41 for a fuel supply line (not shown).

Obviously, in the case of a main combustion chamber comprising a plurality of axially-arranged elongated flame chambers, there should still be at least two flame chambers provided with igniter chambers, and all the flame chambers may be provided with interconnecting passages and, if desired, with auxiliary spraying devices, arrange-d rapidly to propagate the flame when starting.

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

1. An igniter chamber for a main combustion chamher, for a gas turbine engine, of the kind having a flame chamber along the outside of which diluent air is caused to flow from the outlet of a compressor of the engine to the inlet of the turbine, said flame chamber having a baffle at its upstream end, a plurality of pipes supported from said bafiie at the downstream side of the latter, each of said pipes having an outlet end displaced laterally with respect to the axis of the inlet end of said pipe, said inlet end of each said pipe to receive an injection of fuel with primary air and to deliver it into said flame chamber, and a plurality of further combustion air supply means at the downstream side of said baffle in said flame chamber, said igniter chamber mounted on the upchamber on the upstream side of said baffle, said igniter chamber having an opening at its upstream side for the supply thereto of primary air, a battle means within said igniter chamber in the path of the primary air through said igniter chamber, a starting fuel nozzle, means for supplying oxygen to the vicinity of said nozzle, said nozzle delivering a-spray of starting fuel through said handle means into primary air which has passed said baffle means, said spray entraining oxygen delivered to said vicinity, an igniter for said starting fuel, at least one opening said igniter chamber for the admission of secondary air for assisting combustion of the starting fuel before flame passes from the igniter chamber, and an outlet in said igniter chamber communicating with the downstream side of said baffle in said flame chamber in the position which otherwise would have been occupied by said one further combustion air supply means, which said igniter chamber has replaced, the total area of said primary air and said secondary air openings in said igniter chamber being substantially equal to the area of said one further combustion air supply means.

3. An igniter chamber for a main combustion chamber, for a gas turbine engine, of the kind having a flame chamber along the outside of which diluent air is caused to flow from the outlet of a compressor of the engine to the inlet of the turbine, said flame chamber having a baflle at its upstream end, at least one pipe supported from said bafiile at the downstream side of the latter, said pipe having an outlet end displaced laterally with respect to the axis of the inlet end of side pipe, said inlet end of said pipe to receive an injection of fuel with primary air and to deliver it into said flame chamber, and further combustion air supply means at the downstreamside of said bafiie in said flame chamber, said igniter chamber on the upstream side of said baffle, said igniter chamber having an opening at its upstream side for the supply thereto of primary air, a flat annular bafiie means Within said igniter chamber, the open center of said battle stream side of said baffle in place of one of said further combustion air supply means, said igniter chamber having an opening at its upstream side for the supply thereto of primary air, a battle means within said igniter chamber in the path of the primary air through said igniter chamber, a starting fuel nozzle, said nozzle delivering a spray of starting fuel through said baflie means into primary air which has passed said. bafiie means, an igniter for said starting fuel, at least one opening in said igniter chamber for the admission of secondary air for assisting combustion of the starting fuel before flame passes from the igniter chamber and an outlet in said igniter chamber communicating with the downstream side of said bafllle in said flame chamber in the position, which otherwise would havebeen occupied by said one further combustion air supply means, which said igniter chamber has replaced, the total area of said primary air and said secondary air openings in said igniter chamber being substantially equal to the area of said one further combustion air supply means. 1

2. An igniter chamber for a main combustion chamber, for a gas turbine engine, of the kind having a flame cham: ber along the outside of which diluent air is caused to ilow from the outlet of a compressor of. the engine to the inlet of the turbine, said flame chamber having a baffle at its upstream end, at least one pipe supported from said bathe at the downstream side of the latter, said pipe having an outlet end displaced laterally with respect to the axis of the inlet end of said pipe, said inlet end of said pipe to receive an injection of fuel with primary air and to deliver it into said flame chamber, and further combustion air supply means at the downstream side of said baflle in said flamechamber, said igniter means being sharp edged, a starting fuel nozzle, said nozzle delivering a spray of starting fuel through the open center of said baffle means into primary air which has passed said baflle means, an igniter for said starting fuel, at least one opening in said igniter chamber for the admission of secondary air for assisting combustion of the starting fuel before flame passes from the igniter chamber, and an outlet in said igniter chamber communicating with the downstream side of said bathe in said flame chamber in the position, which otherwise would have been occupied by said one further combustion air supply means, Which said igniter chamber has replaced, the total area of said primary air and said secondary air. openings in said igniter chamber being substantially equal to the area of said one further combustion air supply means.

4. An igniter chamber for a main combustion chamher, for a gas turbine engine, of the kind having a flame chamber along the outside of which diluent air is caused to flow from the outlet of a compressor of the engine to the inlet of the turbine, said flame chamber having a bafile at its upstream end, a plurality of J-like pipes supported from said baflie at the downstream side of the latter, each of said pipes having an outlet end displaced laterally with respect to the axis of the inlet end of said pipe, said inlet end of each said pipe to receive an injection of fuel with primary air and to deliver it into said flame chamber, and a pturality of further combustion air supply means at the downstream side of said baflie in said flame chamber, said igniter chamber mounted on the upstream side of said bathe in place of one of said further combustion air supply means, said igniter chamber having an opening at its upstream side for the supply thereto of primary air, a bafile means within said igniter chamber, said baffle means comprising a flat annular baflic arranged in a plane normal to the axis of said igniter chamber and a cylinder baflie of greater diameter than the nozzle delivering a spray of starting fuel through the 5 open center of said annular bafiie into primary air which has passed through said annular constriction, an igniter for said starting fuel, at least one opening in said igniter chamber for the admission of secondary air for assisting combustion of the starting fuel before flame passes from the igniter chamber, and an outlet in said igniter chamber communicating with the downstream side of said bafiie in said flame chamber in the position, which otherwise would have been occupied by said one further combustion air supply means, which said igniter chamber has replaced, the total area of said primary air and said secondary air openings in said igniter chamber being substantially equal to the area of said one further combustion air supply means.

5. An igniter chamber, for a main combustion chamber, according to claim 4 and also including means for supplying oxygen to the vicinity of the nozzle, said oxygen to be entrained by the starting fuel spray.

References Cited in the file of this patent UNITED STATES PATENTS 2,404,335 Whittle July 16, 1946 2,541,900 Williams Feb. 13, 1951 2,625,011 Allen Jan. 13, 1953 2,646,109 Banscher July 21, 1953 2,662,373 Sherry et a1. Dec. 15, 1953 2,693,676 Hamm -Nov. 9, 1954 2,701,445 Andrews et al. Feb. 8, 1955 2,734,341 Lovesey Feb. 14, 1956 2,758,441 Kalil et al. Aug. 14, 1956 2,765,621 Poulston et al. Oct. 9, 1956

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