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Патент USA US3024616

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March 13, 1962
Filed July 10, 1958
2 Sheets-Sheet 1
as zz
March 13, 1962
Filed July 10, 1958
2 Sheets-Sheet 2
United Sates Patent ?fice
Patented Mar. 13, 1952
From the turbine 16 the exhaust gases discharge through
an exhaust duct 22 and thence through a nozzle 24 into
the surrounding atmosphere. The nozzle 24 is formed
by a rigid centerbody structure 26 having an enlarged
plug~type end 28 and by an axially movable wall struc
Donald B. Adams, Wyoming, Ohio, and Donald P. Sulli
van, Van Nuys, Cali?, assignors to Curtiss-Wright Cor
poration, a corporation of Delaware
ture 30. The wall structure 30 forms a continuation of
the exhaust duct 22 and has a ?ared end 32 so that axial
adjustment of the wall structure 30 is effective to vary the
Filed .‘iuly 1t), 1958, Ser. No. 747,608
3 Claims. (Cl. 60—39.66)
This invention relates to jet engines and is particularly
nozzle area.
directed to an arrangement for cooling the walls of a
hot gas or combustion chamber for such an engine.
In the case of a turbo-jet engine with an afterburner the
Walls of the afterburner combustion chamber and exhaust
Fuel nozzles 34 and 36 are provided for supplying
fuel to the exhaust duct 22 for combustion therein down
stream of the ?ameholder structure 38 so that the space
40 downstream of said ?ameholder structure forms the
duct and nozzle are subjected to extremely high tempera
combustion chamber for the engine afterburner.
ture gases. This is particularly true when the turbojet 15
The details of the afterburner and nozzle end of the
engine is operating at high supersonic Mach numbers.
engine are more clearly shown in FIGS. 2-6 together
Similarly the walls of the combustion chamber and ex
with the arrangement of the invention for cooling the wall
haust passages of ramjet and rocket engines are also sub
structure of said afterburner and nozzle.
jected to high temperatures. The use of a hollow wall
Referring now to FIGS. 2-6 the wall structure for the
structure for jet engines in which liquid fuel is circulated 20 outer portion of the afterburner chamber 40 forms a
therethrough prior to combustion in the engine is a
continuation of the exhaust duct 22. This wall structure
known expedient for maintaining the temperature of the
comprises a hollow outer wall 42 formed by radially
wall structure within safe operating limits. When liquid
spaced annular layers 44 and 46 of sheet metal secured
hydrocarbon fuel is so used, the fuel vaporizes and as a
together by a corrugated sheet-metal member 48 disposed
consequence high pressures are required to keep the fuel
between said layers to form a hollow rigid wall 42. The
volume within reasonable limits. This is particularly true
corrugations of the member 48 are secured to and run
at the high temperatures produced in the engine at high
axially between the layers 44 and 46 to form longitudinally
supersonic ?ight speeds. Furthermore, if a hydrocarbon
extending passages 50 therebetween.
fuel remains at too high a temperature for too long a
The corrugated member 48 terminates short of the
period of time, it will crack, that is the more complex 30 downstream end of the hollow wall 42 to leave an annular
hydrocarbons of the fuel break up into hydrocarbons of
space 52 between its layers 44 and 46 at said down
less complex structure. Such fuel cracking is also ob
stream end. An annular manifold structure 54 is pro
jectionable because along with other factors such as fuel
vided at the upstream end of the hollow wall 42 for
oxidation it tends to cause coking deposits to build up
supplying a liquid coolant thereto for ?ow through the
along the passage walls.
passages 50.
An object of the invention comprises the provision of
The manifold structure 54 has a pair of annular inlet
an arrangement for cooling the wall structure of a jet
and outlet parts 56 and 58 separated by partition means
engine by circulating a liquid through passages in said
559 such that the annular inlet port 56 is in communica
wall structure and also through a heat exchange structure
tion with only alternate passages 50 and the outlet part
for transferring heat to the jet engine fuel. This arrange 40 58 is in communication with only the remaining passages
ment permits the use of a cooling liquid having relatively
59. With this construction of the manifold 54, a liquid
high thermal capacity, as for example a liquid metal such
supplied to the inlet port 56 will ?ow through half the
as sodium or a eutectic mixture of sodium and potassium.
passages 50 to the annular space 52 at the downstream
end of the hollow wall 42 and then ?ow back upstream
Also, with this arrangement, the heat from the cooling
liquid can be rapidly transferred to the engine fuel in a
heat exchange structure immediately prior to its discharge
into the engine combustion chamber. This arrangement
through the remaining passages 56 to the annular outlet
45 port 58 in the manifold 54.
A pump 60 is provided for circulating a suitable cooling
liquid through the passages 50 of the hollow wall 42.
permits the use of hydrocarbon fuels which would crack
if they were used directly for cooling said wall structure
For this purpose the pump 60 has a supply line 62 con
nected to the inlet port 56 of the annular manifold 54.
From the outlet port 58 of the manifold 54 the liquid cool
ant is returned to the pump 6% through the line 64 and a
heat exchange structure 66 and thence through a line 68
back to the pump whereby said passages and heat ex
because of the relatively long length of time the fuel
would require for circulation through said wall structure.
Other objects of the invention will become apparent
upon reading the annexed detail description in connection
with the drawing in which:
FIG. 1 is a schematic axial sectional view of a turbojet
changer from a loop passageway for circulation of said
liquid therearound by the pump 60. A suitable expansion
FIG. 2 is an enlarged schematic view of the after
chamber '70 is connected to the outlet side of the pump
69 to accommodate expansion and contraction of the
and illustrating the invention;
liquid coolant so that the hollow wall passages 50 can
FIG. 3 is an enlarged sectional view taken along line
at all times remain full of said liquid.
3——3 of FIG. 2;
The afterburner fuel is supplied by a pump 80 under
FIG. 4 is a view taken along line 4-4 of FIG. 3; and
control of a main fuel regulating valve 82. From the main
FIGS. 5 and 6 are sectional views taken along the
fuel valve 82 a portion of the fuel is supplied direct to
lines 5-—5 and 6——6 of FIG. 4.
the fuel nozzles 34 via the fuel line 84. The remaining
Referring ?rst to FIG. 1 of the drawing, reference num
portion of the fuel is supplied to the fuel nozzles 46
eral ltl designates a turbojet engine having a compressor
through the heat exchange structure 66, valve 86 and
12 supplying compressed air to a main combustion cham
fuel line 88. The afterburner fuel nozzles 3.6 aredis
ber 14 which in turn supplies combustion gases to the
posed vbut a short distance upstream of the ?ameholder
turbine 16 for driving said turbine. The combustion
structure 38. The afterburner fuel nozzles 34, however,
chamber fuel supply nozzles are shown at 18. The turbine
are disposed a substantial distance upstream of the fuel
16 is drivably connected to the compressor 12 by the
nozzles 36 and the afterburner ?ameholder- structure 38.
burner and exhaust end of the turbojet engine of FIG. 1
shaft Ztl.
The valve 82 regulates the total fuel supply to the
burner can be kept su?iciently short to minimize crack
afterburner fuel nozzles 34 and 36 while the valve 86
regulates the division of fuel ?ow between said nozzles.
ing of the fuel.
The valve 86 preferably is automatically controlled by
In order to minimize the‘heat transfer from the after~
burner combustion gases to the liquid coolant in the hol
the temperature of the fuel as it leaves the heat exchanger
66 such that during operation the temperature of the fuel,
as it leaves the heat exchanger 66, is maintained at least
approximately at a predetermined value, for example
900° F. Thus any increase in said temperature above
900° F. results in opening adjustment of the valve 86
low wall passages 50, the wall structure for the outer
portion of the afterburner chamber 40 also includes a
heat barrier or insulating layer 100 disposed over the
inner surface of the hollow wall 42. The heat insulating
layer preferably is of a sheet metal honeycomb construc~
so that a larger percentage of the fuel is diverted through 10 tion having an inner cylindrical shell 102 with a honey
comb structure 104 disposed between said shell and the
the heat exchanger 66. In this way the valve 86 is auto~
hollow wall ‘42. The inner shell 102 has longitudinally
matically operative to prevent the temperature of the
extending corrugations 106 to facilitate expansion and
fuel supplied thru the heat exchanger 66 from exceeding
contraction of said shell. The walls of the honeycomb
a predetermined value. Temperature control of the valve
structure 104 have openings 108 so that the cells of said
86 is schematically indicated as comprising a conventional
structure are interconnected. These interconnected cells
?uid ?lled temperature responsive bulb 90 in the fuel line
are vented to the surrounding atmosphere for example
38 at the heat exchanger ‘66. The bulb 90 is connected
by the passage indicated at 110.
to a bellows 92 which in turn is mechanically connected to
The honeycomb layer 100 prevents the heat loss from
bulb 90 results on opening adjustment of said valve 20 the afterburner gases to the liquid coolant in the passages
50 of the hollow wall 42 from becoming excessive. Also
against the spring 94.
because of the corrugations 106 the layer 100 will tend to
With the structure described, circulation of the liquid
expand with internal pressure so that it transmits the in
coolant through the passages 50 of the afterburner hol
ternal pressure to the liquid cooled hollow wall ‘42. With
low wall 42 serves to keep the temperature of said wall
below a maximum safe value. The heat absorbed by 25 this arrangement the relatively cool outer wall 42 carries
all the structural loads while the inner wall or layer 100
the liquid coolant is extracted in the heat exchanger 66
the valve 86 so that an increase in fuel temperature at the
not only acts as a heat barrier but, because of its re~
by the ‘fuel ?owing therethrough in heat exchange rela
siliency, also acts to transfer the internal gas pressure
tion to said coolant. This fuel is heated to a sut?ciently
loads to the cool outer wall. Having the loads all car
high temperature in the heat exchanger 66 so that it
vaporizes therein or it at least vaporizes promptly upon 30 ried by the relatively cool wall 42 minimizes the re~
being discharged into the afterburner from the down
stream fuel nozzle 36. The fuel nozzles 34 are disposed
a substantial distance upstream of the ?ameholder struc
ture 38 so as to give this unheated portion of the fuel
time to vaporize and mix with the turbine exhaust gases
before reaching the ?ameholder.
The cooling liquid circulated through the passages 50
of the hollow afterburner wall 42 preferably is a metal
which is in the liquid state at the temperatures of the
turbine exhaust. Hence the coolant metal will become
a liquid before the engine after-burner is started. A suit
able metal ‘for this purpose is an eutectic mixture of so
dium and potassium. Other metals such as pure sodium
may also be used. Such a liquid coolant has the ad
vantage of a high thermal capacity so that it will absorb
a large amount of heat with a relatively small tempera
ture rise.
quired weight of the afterburner wall structure.
The wall structure of the centerbody 26 and plug 28
and that of the axially movable wall 30 are all subjected
to the hot afterburner gases. Each of these wall struc
tures, like that for the outer portion of the afterburner
combustion chamber 40, includes a hollow liquid cooled
wall together with a honey-comb layer disposed over said
hollow wall to function as a heat ‘barrier.
In the case of the centerbody 26, the hollow wall 120
of said centerbody has an outlet annular manifold 122 at
one end and an inlet annular manifold 124 adjacent the
maximum diameter portion of the plug 28. The pump 60
is connected to the inlet manifold 124 by a line 126 and
a line 128 returns the coolant from the outlet manifold
122 to the return line 64. In this way all the liquid cool
ant supplied to the manifold 124 ?ows longitudinally
through passages (similar to the passages 50) in the hol
If a hydrocarbon fuel were used directly as the ?uid
low wall 120 to its outlet manifold 122 to cool said well.
coolant in the passages 50 it would vaporize therein and
would require large pressures to keep the volume of the
fuel required for cooling within reason. This would mean
Liquid coolant is also supplied by the line 126 to ‘an
inlet manifold 130 at the rear end of the plug 28 from
which it flows through passages (similar to the passages
50) in its hollow wall 132 to an outlet manifold 134
which is connected to the return line 128.
that with a hydrocarbon fuel as the coolant for the pas
sages 50, the walls of said passages would have to be
strong enough to withstand much higher pressures than
is required when a liquid metallic coolant is so used.
Also because of the large surface area of the hollow wall
structure 42 required to be cooled a substantial time is
required for circulation of the coolant thru its passages
Hence if a hydrocarbon fuel were used as a cool
ant in these passages the fuel would tend to crack be
cause of the temperature the fuel would attain and be
cause of the length of time the fuel would be at this
temperature. Such cracking is objectionable because it
Likewise liquid coolant is supplied by the pump 60 and
supply line 142 to an annular inlet manifold 144 disposed
at ‘a mid or intermediate point along the hollow wall 146
of the movable wall structure 30. The inlet manifold
144 communicates with only alternate passages (similar
to the passages 50) in the hollow wall 146 and only with
the portion of said passages along the upstream portion
of said wall. A partition 148 is disposed across only these
alternate passages at said mid or intermediate point. An
annular outlet manifold 150 is disposed adjacent to the
inlet manifold and communicates with only the same al
changes the structure of the fuel and in addition fuel
cracking along with other factors such as fuel oxidation 65 ternate passages as the inlet manifold but on the other
side of the partition 148. Liquid supplied to the inlet
in the passages ‘50 would tend to cause coking deposits
manifold 144 flows through said alternate passages to an
to build up along the walls of said passages.
annulus 152 at the upstream end of the hollow wall 146
By using a liquid metal coolant to cool the hollow wall
and thence through the other passages in the hollow wall
42 and then transferring the heat from the liquid coolant
to the fuel in the heat exchanger 66, the heat can be 70 146 to an annulus 154 at its downstream end and then
through the first mentioned alternate passages to the out
transferred rapidly to the fuel so that the fuel is at a high
let manifold 150 which in turn communicates with the
temperature for only a short period of time before it is
return line 64.
discharged into the engine afterburner at the ‘fuel nozzles
Since the wall 30 is axially movable the connections to
36. With this arrangement the length of time the fuel
is at the high temperature before burning in the after 75 the manifolds 144 and 150 are ?exible as schematically
indicated on the drawing ‘at 160 and 162 respectively.
Linkage 164 is connected to the wall 38 for axially ad
justing its position to vary the nozzle area.
The hollow walls 120, 132, and 146 are provided with
means for regulating the division of fuel ?ow from said
common source to said two nozzle structures.
heat barrier layers 166, 168, and 170 respectively of
2. The combination claimed in claim 1 and in which
said last mentioned means comprises valve means; and
means responsive to the temperature of the fuel leaving
honeycomb construction similar to layer 101} of the hollow
said heat exchange structure and operatively connected
wall 42. Actually the outer wall structure of the after
to said valve means for increasing the fuel ?ow thru said
burner chamber 40, the wall structure of the centerbody
heat exchange structure should said temperature exceed
26, plug 28, and movable wall 38 essentially are all the
a predetermined value.
same. The only diiferences lie in the various manifold 10
3. The combination recited in claim 2 in which said
arrangements described for circulating the liquid coolant
wall construction has an inner layer providing a heat bar
through their hollow ‘walls.
rier ‘between said hot gases and said rigid hollow wall,
While we have described our invention in detail in its
said inner layer having a honeycomb construction with an
present preferred embodiment it will be obvious to those
inner shell closing the cells of said honeycomb to the hot
skilled in the art after understanding our invention that 15 gases, said inner shell having corrugation to permit out
various changes and modi?cations may be made therein
ward expansion thereof.
without departing from the spirit or scope thereof.
We claim as our invention:
References Cited in the ?le of this patent
1. In combination with a jet engine having a chamber
thru which the engine combustion gases flow at sub
stantial velocity, said chamber having a hollow wall pro
viding a rigid wall structure with a plurality of passages
Handy _______________ __ Aug. 9, 1932
therethru; means providing a loop passageway including
Dawes _______________ __ Jan.
Reynolds _____________ __ June
Bartlett et al __________ __ Apr.
Godfrey ______________ __ Feb.
said hollow wall passages; a coolant within said loop pas
sageway for circulation therearound for cooling said hol
low wall, said coolant being a metal which is in the liquid
state during engine operation; two nozzle structures for
discharging fuel into said engine for combustion therein
‘and ?ow of the combustion gases thru said chamber, said
two nozzle structures being spaced so that one is disposed 30
a substantial distance downstream of the other; a com
mon source of fuel having passage connections to both
said nozzle structures; a heat exchange structure inter
posed in the flow path of said liquid coolant to and from
said chamber Wall and in the ?ow path of fuel ?ow from 35
said common source only to the downstream one of said
two nozzle structures for ?ow of said latter fuel and
liquid coolant thru said heat exchanger in heat exchange
relation for transferring heat from said liquid coolant to
the fuel supplied to the ‘downstream nozzle structure; and 40
Wood _______________ __ Dec. 1, 1925
Bridgeman ___________ __ Sept. 27, 1955
Sharpe _______________ __ Oct. 18, 1955
Collins _______________ __ Jan. 1, 1957
Karen _______________ __ Feb. 12, 1957
Mortimer ____________ __ May 28, 1957
Stockdale ____________ __ June 4, 1957
Halford et a1. _________ __. Apr. 7, 1959
Johnson et a1 __________ __ Feb. 23, 1960
Canada _____________ __ Dec. 23, 1952
Great Britain __________ __ Jan. 4, 1917
Great Britain _________ __ Feb. 28, 1949
Great Britain _________ __ Oct. 31, 1956
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