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Патент USA US3045435

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July 24, 1962
T. SEIFFERLEIN
3,045,425
EXHAUST REHEAT EQUIPMENT FOR GASrTURBINE ENGINES
Filed Feb. 21, 1955
,.
United States Patent 0 ” ICC
3,645,425
Patented July 24, 1962
2
1
turbine without subjecting the latter to an excessive tem
perature, even momentarily.
3,045,425
EXHAUST REHEAT EQUIPMENT FOR GAS
In accordance with the invention there is introduced in
TURBINE ENGINES
the midst of the ‘hot driving gases on the upstream side
Theo Seifferlein, Dammarie-les-Lys, France, assignor t0
of the turbine, a concentrated jet of fuel directed towards
Societe Nationale d’Etude et de Construction dc Mo
the turbine, the rotation of this latter serving to produce
teurs d’Aviation, Paris, France, a French company
‘a suf?ciently high degree of vaporisation of the fuel to
Filed Feb. 21, 1955, Ser. No. 489,446
enable it to be ignited, on the downstream side of the
Claims priority, application France Mar. 3, 1954
turbine, by the action of the hot gases which are dis
2 Claims. (Cl. Gil-35.6)
10 charged therefrom. This jet of fuel is preferably com
bined with an admission of cold air, which may be the
The present invention relates to an improvement in ex
secondary air under pressure delivered from the com
haust reheat devices for gas turbine engines, and more
pressor which supplies the combustion chamber, this air
particularly in after-burning devices for turbo-jet units.
being intended to prevent, at least in part, any direct con
It is known that the temperature of the motive gases in
tended to drive a gas turbine should be limited in order to 15 tact between the fuel of the jet and the hot gases on the
upstream side of the turbine. To this end, this air may
‘avoid damage to the turbine. On the other hand, it is also
be introduced through an orifice located in the vicinity of
known that, at the outlet of the turbine, the temperature
the fuel-injection member, and preferably surrounding the
of the gases is substantially lower than at its inlet, as a
said member, so that the air forms a cold protective sheath
result of the expansion to which these gases are subjected.
around the jet ‘by which it is entrained.
It is however often necessary to have, ‘at the outlet of a
The output ‘of fuel introduced in the form of a jet into
turbine, gases at high temperature which are intended to
the combustion chamber may be suf?cient in itself to
supply additional work which, for example, will enable the
ensure the desired after-burning; in the contrary case, a
thrust to be increased in the case of a turbo-jet unit. To
supplementary quantity of fuel may be introduced on the
this end, devices are provided known as after-burning de
vices, that is to say devices which enable 1a combustion 25 downstream side of the turbine, in the zone in which is
produced the ?ame due to the combustion of the ?rst
to be effected in the midst of the exhaust gases from the
mentioned fuel after its vaporisation by the turbine.
turbine with the object of increasing the temperature of
The description which follows below with regard to the
these gases, which cannot, of course, run any risk of dam
attached drawings (which are given by way of example
aging the turbine, since the combustion takes place on the
only and not in any sense ‘by way of limitation) will make
downstream side of this latter.
it quite clear how the invention may be carried into effect,
The known after-‘burning devices comprise injectors
the special ‘features which may be brought out, either in
mounted in the exhaust conduit of the turbine, these
the drawings or in the text, being understood to form a
injectors serving to introduce a supplementary quantity of
part of the said invention.
fuel into the flow of exhaust gas which still contains a high
proportion of combustion-supporting air.
As has already been stated, the temperature of the
gases which is already restricted on the upstream side of
35
FIG. 1 is a schematic view in axial cross-section of a
turbo-jet unit embodying an application of the improve
the turbine, falls considerably as a result of the expansion
ment in accordance with the invention.
FIG. 2 is a partial view to a larger scale.
which takes place in the turbine, to the point of making
problematical the ignition of the supplementary fuel, and
there can be seen at C the air compressor of the turbo-jet
In the form of embodiment shown in the drawings,
unit, at Ch, the combustion chambers, at T the gas turbine,
and at R the reaction discharge nozzle provided with any
known arrangement S for controlling the effective cross
It has already been proposed to use ignition burners
section of its outlet ori?ce. The combustion chambers
mounted in the combustion chamber which precedes the
turbine and permitting of the introduction into this com 45 Ch are supplied with fuel by means of the burners B of
standard type, whilst in the exhaust conduit of the turbine
bustion chamber of a certain amount of fuel intended to
T, there is mounted an after-burning fuel injection system
produce an appreciable increase in the temperature of the
Pc cooperating with ?ameholding ba?les E for stabilising
gases on the upstream side of the turbine and especially a
the ?ame.
flame which, passing through the turbine, reaches the
The combustion chambers Ch have walls slightly spaced
after-burning injectors and ensures by this means the
‘apart from those of the casing M of the engine, in known
ignition of the fuel discharged by these injectors. How
this ignition thus necessitates the use of special accessory
devices of a more or less complex kind.
ever, precautions must be taken so as to avoid an exces
manner, so as to form a conduit A enabling the circula
tion of secondary cooling air around the combustion
sive increase in the temperature of the gases on the up
chambers Ch. Lateral openings 0 are ‘formed in the walls
stream side of the turbine and also to avoid an excessive
duration of this operation, so that the ?ame which passes 55 of the combustion chambers so as to permit a part of this
secondary air to pass into the interior of the chambers and
through the turbine is not too intense and does not have
thus to effect a dilution of the burnt gases before these
time to damage the turbine blades. It is especially neces
gases pass into the turbine.
sary to adjust the supply of supplementary fuel to the com
In conformity with the present invention, one or a num
bustion chamber in a very precise mnaner on the one
hand, and strictly to limit the time of this injection of 60 ber of injectors I is arranged in one or a number of com
bustion chambers Ch in the vicinity of the nozzle guide
supplementary fuel on the other hand. This necessarily
vanes D of the turbine T. This injector I is placed in one
involves the use of delicate and complicated control de
of the openings 0 and it is arranged in such manner as to
vices, and creates a most unfortunate liability in that if,
produce a strongly concentrated jet J of fuel which is
for any accidental reason, the ignition of the fuel dis
charged from the laftereburning injectors does not take 65 directed towards the nozzle guide-vanes D. This jet, by
reason of its high velocity, entrains part of the secondary
place almost at once, it is impossible to prolong the action
air which thus forms around it a kind of protective cold
of the ignition burners without running the risk of irrep
sheath which prevents direct contact of the fuel forming
arably damaging the turbine.
the jet I with the hot gases generated by the combustion
The present invention has for its object an after-‘burning
device which enables the drawbacks referred to above to 70 chamber, and thus avoids any risk of general ignition of
be overcome and which especially ensures the ignition of
the supplementary fuel on the downstream side of the
the fuel on the upstream side of the turbine T.
This jet, which passes through the guide-vanes D and
3,045,425
3
4
the blades of the turbine, is subjected to a considerable
turbulence which ensures intense atomisation and pre
and especially by the substitution of equivalent technical
means, without thereby departing from the spirit or from
vaporisation of the fuel, so that the latter when discharged
from the turbine, is atomised and in intimate contact with
the scope of the present invention.
What I claim is:
the ‘hot exhaust gases from the turbine in a zone at which
the gases have still a fairly high temperature . This inti~
mate contact ensures the ignition of the fuel and there is
1. In a turbojet engine having a combustion space, a
gas turbine and an exhaust-reheat tail pipe in series ?ow
formed a ?ame P which reaches the after-burning injec
a fuel injection nozzle designed to form a concentrated,
arrangement, an exhaust-reheat ignition device comprising
solid jet of fuel and positioned at a peripheral point of
ba?les E. In its turn, this ?ame ensures infallibly the igni 10 said combustion space, said nozzle pointing towards said
turbine, and a cool air supply leading to said peripheral
tion of the fuel injected from P0.
point, around said nozzle, whereby said concentrated jet
It will be observed that, contrary to the known arrange
induces a sheath of cool air substantially surrounding said
ments referred to above, the ‘fuel discharged from the in
jet.
jector I does not burn in the combustion chamber Ch,
tors Po and preferably, even as far as the ?ame-stabilising
and there is thus no increase in temperature on the up
2. In a turbojet engine having an air compressor, a com
stream side of the turbine, and the injection period may
bustion chamber, a gas turbine, an exhaust-reheat tail
pipe in series flow arrangement, and a ?ame-tube with
be prolonged to any desired extent, and even for the whole
a ported wall extending in said combustion chamber and
period of operation of the after-‘burning system. Further
dividing it into an inner ?ow path of primary combustion
more is not necessary to provide complicated devices for
controlling the quantity of .fuel delivered, since the latter 20 air and an outer ?ow path of secondary cool air, said
paths communicating through the ports of said wall, an ex
has simply to be sufficient for the ?ame F produced on
haust-reheat ignition device comprising a fuel injection
the downstream side of the turbine to be long enough to
nozzle designed to form a concentrated, solid jet of fuel
reach the rafter-burning ring Pc and preferably the baf?es
and positioned at one of said ports, said nozzle pointing
E. This after-burning ring could even be dispensed with,
the total quantity of supplementary fuel being then sup
plied by the injector or injectors I.
It will, of course, be understood that the application of
the invention is not in any way limited to after-burning
devices for turbo-jet units, but extends to any re-heating
device for the gases on the downstream side of a turbine 30
which makes use of a supplementary injection of fuel on
the upstream side of the said turbine, in the form of a
concentrated jet directed towards the turbine. In partic
ular, the invention may ?nd an interesting application in
the case in which it is desired to effect re-heating of the
driving gases between turbines in series flow arrangement,
in certain gas-turbine installation.
It will also be clear that modi?cations may be made
to the form of embodiment which has just been described,
towards said turbine, whereby said concentrated jet in
duces a sheath of cool air substantially surrounding said
jet.
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,502,332
2,520,967
2,616,257
2,636,344
2,640,316
McCollum ___________ __
Schmitt _____________ __
Mock _______________ __
Heath _______________ __
Neal _______________ __
Mar. 28,
Sept. 5,
Nov. 4,
Apr. 28,
June 2,
2,651,178
2,715,311
2,780,061
Williams _____________ __ Sept. 8,
Ooar ________________ __ Aug. 16,
Clarke et a1. _________ __ Feb. 5,
2,780,915
Karen _____________ __ Feb. 12,
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