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Патент USA US3082612

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March 26, 1963
H. HERING ETAL
3,082,603
COMBUSTION CHAMBER WITH PRIMARY AND SECONDARY AIR FLOWS
Filed Oct. 2, 1956
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HANS Hsama
Lemma Msuz
EDOUARD CAFFIER
ATTORNEYS
United States Patent 0 ice
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and divides into two parts, one part forming the primary
air of combustion passing in the direction of the arrows f
3,082,603
COMBUSTION CHAMBER WITH PRIMARY AND
SECONDARY AIR FLOWS
Hans ' Haring, 'Stuttgart-Zutfenhausen, Germany, and
into the combustion chamber proper or ?ame-tube 2,
through one or a number of ori?ces formed in the head
Lothar Menz, Paris, and Edouard Ca?ier, Montfermeil,
of this tube, the other part of the air circulating inside
the space formed between the ?ame-tube 2 and the ?ared
conduit 1a and passing into the said ?ame-tube towards its
France, assignors to Societe Nationale d’Etudes et de
Construction de Moteurs d’Aviation, Paris, France, a
French company»
i
3,082,603
Patented Mar. 26, 1953
-
end portion. The example given in the drawing shows
. Filed Oct. 2,1956, Ser. No. 613,497
Claims priority, application France Oct. 28, 1955
2 Claims. (Cl. 60-3965)
an admission device for primary air of known type, com
10 prising two concentric open tubes 3, 4 of frusto-conical
shape, connected to each other by radial arms 5.‘ The
fuel injector 6 discharges in the axis of the internal tube
3. A part of the primary air which passes in through
which enable both a high ei?ciency (total combustion),
the large ori?ce 7 formed at the head of the tube 2, passes
a very low limit of extinction, a low loss of pressure and 15 through the annular space between ‘the internal tube 3' and
especially a uniform distribution of temperature in the
the injector 6. The greater part of the primary air passes
radial and peripheral directions to be obtained. In gas
into the channels vformed all around the tube 3 by this
turbine engines, it is in fact desirable to prevent local
tube itself, the radial arms -5 and the peripheraleral tube 4.
It is dif?cult to design combustion chambers which are
able to comply at the same time with the conditions ,
peaks of temperature produced by the combustion, since
The radial arms form wake zones on the downstream
such peaks are dangerous for the blades of the turbine. 20 side of the ?ow, in which the ?ame may be initiated and
The distribution of temperatures gives rise to great
stabilized.
di?iculties when the mixture becomes increasingly rich,
Other burner devices exist which also comprise stabiliz
and thus the increases in power of turbo-machines are
ing screens playing the same part as the radial arms 5, in
limited by thermal considerations.
order to create wake zones in which the ?ame may be
The present invention has for its object a combustion 25 stabilized. Whatever may be the nature of the device,
chamber device which complies to a very great extent
measurements made in the same rectangular cross-section
with the requirements of e?‘iciency, low limit of extinction,
of the tube 2 show the existence of zones in which the
small pressure losses and good distribution of temper
temperature is excessive and which coincide with vthe wake
atures.
of the screens.
In this device, the combustion chamber proper or ?ame
tube comprises a reduced section in an intermediate por
tion on the downstream side of the points of admission
of primary air and of fuel.
The applicants have found that with a reduction in
section which is suf?ciently pronounced, it is possible not
only to obtain combustion of the fuel in the primary air
on the upstream side of this reduced portion, but also
and especially to make the temperature uniform by con
traction of the ?ow as it passes through the reduced por
In order to make the temperature uniform, the form
of embodiment of the invention shown in FIG. 1 com
prises a narrowed portion 8 of the tube 2 at a certain
distance on the downstream side of the origin of this
tube, ‘followed by a sharp ?ared portion 9 of the wall of
the tube. The narrowed section 8 imposes a contraction
on the jet of gas in course of ignition. The streams of
burnt gases at high temperature and the less hot streams
of air are thus displaced transversely by the e?ect of the
contraction, brought into intimate contact and mixed to
40
tion, thus preventing the excessive temperature which
gether, which eliminates the local peaks of temperature.
may exist in certain of the streams of the jet, this last
The abrupt ?aring 9 of the wall following the narrowed
result being of course of great value in the supply of gas
portion 8, produces an expansion of the jet with a reduc
turbines.
tion in its speed, but as the divergence is greater than that
The reduction in section of the combustion chamber
of the divergent portion of a correct diffuser, the jet leaves
may be obtained by means of projections formed over 45 the wall 9 and produces vortices, which is also favorable
all or part of the periphery of the said chamber.
to uniformity of temperature. In addition, the passage
Ori?ces ‘for the supply of secondary air are provided
of the jet through the narrowed portion 8 produces a
in the combustion chamber on the downstream side of the
loss of pressure which facilitates the intake of secondary
reduced portion and on the upstream side of the admis
air through the ori?ces such as 10 ‘formed on the down
sion to the turbine. A suitable arrangement of these 50 stream side of the said narrowed portion. Finally, the
ori?ces enables the secondary air to be mixed with the
gases which are admitted to the distributor d of the tur
gases produced by the primary combustion so as to obtain
bine, have a better distribution of temperature than is
a mixing e?ect which further contributes to the uni
the case with present devices.
lformity of temperatures.
In the accompanying drawings:
The distance which separates the reduced portion 8
from the head portion of the ?ame-tube, and also the
amount of this reduction (ratio of cross-sections) may
be determine/d by experiment in each particular case.
FIGURE 2 is a similar view of a modi?ed form:
The reciprocal adaptation of the shape of the combus~
FIG. 1 shows a combustion chamber which may in the
tion
chamber, of the number, the shape, the dimensions
?rst place be assumed to be tubular for the sake of clear 60 and the arrangement of the admission openings for sec
55
FIGURE 1 is a diagrammatic longitudinal section of
an arrangement embodying the invention;
ness of explanation, that is to say it comprises a mean
axis A—-A located inside this chamber. The air sup
plied from the compressor arrives through the conduit 1
ondary air to the value of the narrowed section and to
its position enables the distribution of temperatures to be
controlled as desired.
3,082,603
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By way of example, FIG. 1 shows a narrowed portion,
the distance of which from the origin of the tube 2 is
a little greater than half the length ‘of this tube between
its intake and its outlet towards the distributor d of the
turbine, while the diameter of the narrowed sections is ap—
proximately half the diameter of the tube on the upstream
side of the narrowed portion.
The form of embodiment given in FIG. 2 differs from
that described above by the presence of two successive
narrowed portions 8 and 8a, which play their part in
succession in creating uniform temperature condition.
The forms of embodiment'described are of course ap
plicable to the case of annular chambers, the tubes 1, 1a
and 2 then having an annular shape generated by rota
tion of the pro?les shown on the drawing about an axis 15
whereas the portion of said inner space downstream of
said constriction communicates with said outer space
through ports formed in the divergent section of the
?ame-tube.
2. Combustion chamber as claimed in claim 1, wherein
the ratio of the width of the constriction, measured trans
versely of the general ?ow direction to the maximum
width of the upstream portion of said inner space simi
larly measured, is of the order of 0.5.
References Cited in the ?le of this patent
UNITED STATES PATENTS
parallel to A—-A but displaced (in general the common
axis of the compressor and the turbine), and the burners
945,967
2,525,206
2,546,432
2,644,512
2,687,010
such as 3 and 4 being distributed around this axis.
What we claim is:
2,699,648
Berkey ______ ..'_ ______ __ Jan. 18, 1955
2,825,202
Bertin et a1 ___________ __'._ Mar. 4, 1958
'
1. A combustion chamber comprising a ?ame-tube ex— 20
Mahr ________________ .._ Jan. 11,
Clarke _______________ __ Oct. 10,
Darling ______________ __ Mar. 27,
Durr _________________ __ July 7,
Ellis ________________ __ Aug. 24,
1910
1950
1951
1953
1954
2,828,609
Ogilvie _______ _'_ ______ __ Apr. 1, 1958
2,907,171
Lysholm ______________ __ Oct. 6, 1959
nected with a divergent downstream section, the portion
of said inner space upstream of said constriction being
962,581
998,079
687,667
France ______________ .._ Dec. 12, 1949
France ______________ __ Sept. 19, 1951
Great Britain _________ __ Feb. 18, 1953
gastightly separated from the surrounding outer space
_ 726,491
Great Britain _________ __ Mar. 16, 1955
tending therein in a fore-and-aft direction and bounding
an inner space separated from ‘a surrounding outer space
FOREIGN PATENTS
of said chamber, saidj?ame-tube having, in an intermedi—
ate zone thereof, a sudden constriction smoothly con
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