A fuel combustor comprises a chamber with air and fuel inlets and a combination gas outlet. The fuel is supplied to a vaporization zone and fuel and air are mixed in a pair of mixing chambers, each exemplified by a swirl can. The resultant mixture is directed into a combustion zone within the combustor. Heat pipes are arranged with one end portion substantially in the combustion zone and the other end in the vaporization zone of its appropriate mixing chamber. Some of the heat of combustion is thus carried back upstream into the swirl cans, to vaporize the fuel as it enters the vaporization zone in the swirl can, thereby improving vaporization and fuel mixing

Marek, C. J.

English

NASA Technical Reports Server

United States Patent [191 [I11 4,052,144 
Marek 1453 Oct. 4, 1977 
[54] FUEL COMBUSTOR 
[75] Inventor: Cecil J. Marek, Shaker Heights, 
[73] Assignee: The United State8 of America a8 
Ohio 
reprcrcntd by the AddniBhrtOr of 
the National Aeronautic8 nnd Space 
AdmhIiBtdOII, Washington, D.C. 
[21] Appl. No.: 672,210 
[22] Filed: Mu. 31,1976 
[51] Int. Ci.2 ......................... F34D 15/02; F23R 1/00 
[52] US.  c1. .................................... 431/352; 431/158; 
60/39.51 R; 165/105 
[58] Field of Scucb ............... 431/158, 157, 351, 352; 
165/10S; 60/253, 39.71, 39.51 R 
1561 Reference8 Cited 
U.S. PATENT DOCUMENTS 
3,153,323 10/1964 Hamm ................................. 60/39.71 
3,429,122 U1%9 Pravda et al. .................. 60/39.51 R 
3,593,518 6/1971 Gerrard ........................... 431/352 X 
3,748,853 7/1973 Jones et al. ........... 431/173 X 
3,763,838 10/1973 Lindsey et ai. ...................... 165/105 
3,921,710 1 1/1975 Katayama ............................ 165/105 
3,823,766 7/1974 Sawyer ............................... W39.51 
Primary &miner-Edward G. Favors 
FUEL 
IN 
N IO 
Assistant hkaminer-Larry Jones 
Attorney, Agent, or Firm-N. T. Musial; J. A. Mackin; J. 
R. Manning 
P71 ABSTRACI' 
A fuel combustor comprises a chamber with air and fuel 
inlets and a combination gas outlet. The fuel is supplied 
to a vaporization zone and fuel and air are mixed in a 
pair of mixing chambers each exemplified by a swirl can 
and the resultant mixture is directed into a combustion 
zone within the combustor. Combustion products are 
exhausted, for example, into a turbine inlet. 
Heat pipe means, in this case comprising a pair of heat 
pipes for each swirl can, are arranged each pipe with 
one end portion substantially in the combustion zone 
and the other end portion in the vaporization zone of its 
appropriate mixing chamber. By use of the heat pipe 
means some of the heat of combustion is carried back 
upstream into the swirl cans, to vaporize the fuel as it 
enters the vaporization zone in the swirl can, thereby 
improving vaporization and fuel mixing. Fewer pollut- 
ants are formed and complete combustion is assisted 
because of the improved fuel vaporization and better 
mixing. 
3 Claim, 1 Drawing Figure 
12 .. -..- 
https://ntrs.nasa.gov/search.jsp?R=19780002281 2020-03-20T12:41:14+00:00Z
U.S. Patent Oct. 4, 1977 4,052,144 
4,052,144 
FUEL COMBUSTOR 
The invention described herein was made by an em- 
ployee of the United States government and may be 
manufactured and used by or for the government for 
governmental purposes without the payment of any 
royalties thereon or therefor. 
BACKGROUND OF THE INVENTION 
The present invention relates to combustors, and 
more particularly to combustors in which the fuel is 
vaporized for mixing and combustion with a suitable 
oxidant such as air. A problem with such combustors is 
to secure the vaporization of the fuel as it is mixed with 
the oxidant to enhance mixing and to ensure so far as 
possible complete combustion of the mixture. 
The prior art suggests, for example, using a combus- 
tion chamber in which the heat of combustion of the 
burning fuel supplies heat of vaporization. Usually such 
a combustor operates at fuel rich mixtures leading to 
incomplete combustion. Under these conditions carbon 
monoxide (CO), smoke, and nitrous oxides (NOx) are 
formed. These compounds are undesirable pollutants. 
One expedient heretofore used to assist vaporization 
of the fuel is to reduce the pressure in a vaporization 
combustion chamber through which the fuel passes. 
Such an expedient may now be omitted by employing 
the present invention. Also precombustors sometimes 
used in the prior art are not required with the combus- 
tor embodying the invention, thus eliminating an unde- 
sirable pressure drop. 
It is therefore an object of the invention to provide an 
improved combustor. 
Another objective of the invention is to provide a 
combustor which improves fuel vaporization and mix- 
SUMMARY OF THE INVENTION 
According to the invention a fuel combustion cham- 
ber is provided and a fuel inlet supplying fuel to the 
chamber. The fuel is injected into vaporization zone and 
a heat pipe means is arranged to conduct heat from the 
combustion zone within the fuel chamber to the vapor- 
ization zone. Accordingly a portion of the heat of com- 
bustion is returned by the heat pipe means from the 
combustion zone to the vaporization zone thereby aid- 
ing in fuel vaporization and consequent fuel mixing and 
combustion. 
BRIEF DESCRIPTION OF THE DRAWING 
The foregoing other objects, advantages, and novel 
features of the invention will be more fully apparent 
from the following detailed description when read in 
connection with the sole figure of the drawing which 
illustrates in longitudinal cross-sectional view an em- 
bodiment of the present invention. 
DESCRIPTION OF THE PREFERRED 
EMBODIMENT 
Referring to the sole figure of the drawing, a combus- 
tor comprises wall 10 which may be in the form of a 
surface of revolution about an axis 12. The walls 10 are 
necked down at an inlet 14 thrugh which air is supplied 
as a source of oxidant for the combustor. In the neck 
portion 16 between the main body portion of the walls 
10 and the inlet 14, the combustor gradually enlarges in 
the downstream direction. Within the neck portion 16 
are the inlets 18 to a pair of swirl cans 20. Conical por- 
ing. 
5 
10 
I5 
20 
25 
30 
35 
40 
45 
50 
55 
60 
65 
2 
tions 22 of the swirl cans are enlarged in the down- 
stream direction from inlets 18 to circularly cylindrical 
body portions 24. Vanes 26 are provided internally of 
the swirl cans 20 in the cylindrical portions 24 to swirl 
the incoming mixture in the downstream direction as it 
passes through the cans, thereby increasing the turbu- 
lence and enhancing mixing. 
Alternatively, instead of the vanes 26 as shown the 
swirlers in the swirl cans 20 may, as an alternative (not 
illustrated), take the form of a set of vanes emanating 
from the central axis and all twisted or turned in the 
same sense and extending to the can walls. In this alter- 
native form the vanes are much like the vanes of the 
stator of a compound turbine or l i e  the vanes of an 
ordinary house fan, but stationary. Swirlers and swirl 
cans are in themselves known. 
A fuel manifold 28 has a pair of outlets 30 for each can 
20 whereby fuel is supplied near the inlets 18 of the 
swirl cans 20. A pair of heat pipes 32 are provided 
which extend from a zone which may be termed the 
vaporization zone 34 adjacent the fuel inlets 30 into the 
central portion of the chamber formed by the wall 10. 
Combustion occurs in this central portion which is 
therefore designated the combustion zone 36. Flame 
barriers 38 between each pair of heat pipes 32 tend to 
prevent the flame in the combustion chamber from 
reacting into the vaporization zone causing premature 
fuel combustion. The heat pipes 32 may carry fins (not 
shown) for improved heat transfer between the heat 
pipe walls and the surrounding area or zones. 
A heat pipe in the simple form illustrated here, com- 
prises a metallic container having on the inner surface 
thereof a capillary structure which is essentially satu- 
rated with a vaporizable liquid. The heat pipe acts to 
transfer heat efficiently from one point on its external 
surface to any other point by a vaporization-condens- 
tion cycle. The four general regions of the heat pipe 
include (all internally of the pipe) an evaporator region 
which transfer heat to the inflowing inner liquid, 
thereby vaporizing it, a vapor channel which permits 
vapor to flow from the evaporator to a condensor, the 
condensor which condenses the vapor thereby remov- 
ing heat from it, and the capillary liquid transport sec- 
tion in which the liquid condensate flows back to the 
evaporator. The heat pipe essentially functions as a 
reflux condensor or evaporating-condensing device 
whch uses its internal capillary or wick section to return 
condensed liquid from the condensor to the evaporator. 
A heat pipe is a totally enclosed, simple, mechanically 
static device which can transport large quantities of 
heat over sizable distances almost isothermally, and is 
essentially independent of gravity. When heat is applied 
to the portion 32a of heat pipes 32 adjacent the combus- 
tion zone that heat is conducted quickly and readily to 
the other end of the heat pipe thereby providing a sub- 
stantial heat flow to the other end 32b adjacent the 
vaporization zone. Heat pipes in themselves are well 
known. External vanes (not shown) on the portions 
where heat transfer between the pipe and the external 
volume is desired may be employed. 
A combustor liner 40 is provided within the combus- 
tor spaced close to the walls 10 and generally parallel 
thereto and extending approximately from the neck 16 
along a more sharply necked down portion 42 of the 
walls 10 leading to an outlet portion 44. The liner 40 is 
extended in the downstream direction to protect the 
wall portion 42. The liner 40 is provided with apertures 
4Oa in the area adjacent the combustion zone. An igni- 
4.052.144 
3 
tor which may comprise simply an insulating rod 46 
through which pass a pair of wires 48 terminating in a 
pair of electrodes 50 spaced to provide a spark gap for 
igniting the fuel mixture to initiate combustion. 
In operation fuel enters the combustor through the 
manifold 28 and is supplied to the vaporization zones 34. 
The oncoming air stream divides into portions. A first 
portions indicated by the arrows 52 enters the swirl cans 
at the inlets 18 and in its downstream flow picks up fuel 
in the vaporization zone 34. During operation the end 
portion 32a of the heat pipes 32 receives heat from the 
combustion zone 36 where combustion is taking place. 
Some of this heat is transferred by the heat pipe to the 
end portion 32b in the vaporization zone and warms the 
incoming fuel and air mixture thereby vaporizing or 
tending to vaporize the incoming fuel as the mixture of 
fuel and air travels in the downstream direction within 
the swirl cans 20. The mixture is swirled and mixed by 
the reaction against the vanes 26. The resultant increase 
in the turbulence of the fuel mixture tends to complete 
the vaporization and mixing of the fuel and the air or 
oxidant, and the mixture thereof bums readily as it 
enters the combustion zone 36. Meanwhile a second 
portion of the air stream as indicated by the arrows 54 
passes between the swirl cans 20 and the liner 40 and 
thereby provides additional air or oxidant as it passes 
along beyond the ends of the swirl cans 20 in the down- 
stream direction into the combustion zone. A third flow 
of air indicated by arrows 56 passes in the downstream 
direction between the liner 40 and the walls 10 and for 
the most part passes through apertures 4Oa to be di- 
rected toward the combustion zone 36. This third air 
flow together with the second air flow tends to cool the 
combustor liner 40. As the air flow portions indicated 
by arrows 54 and 56 enter the combustion chamber they 
tend to dilute the combustion mixture by providing an 
excess of oxidant thereby enhancing complete combus- 
tion and tending to reduce or eliminate pollutants. 
Preheating the inlet stream in the fuel zone 34 by the 
energy transferred by the heat pipes 32 from the com- 
bustion zone to the vaporization zone not only pro- 
4 
motes vaporization but the inlet stream mixture is 
heated. The result is an increase in the combustion sta- 
bility and the combustor may be operated at a higher 
velocity of its inputs, and at greater heat release rate, 
5 thereby allowing for reduction in engine size and 
weight for an equivalent output. The operating temper- 
ature of the heat pipes at least in the area near vaporiza- 
tion zone 34 should be kept below the ignition tempera- 
ture to prevent combustion from occuring within the 
lo vaporizer and mixer, such as within the swirl cans 20. 
On start up the combustor relies on air atomization until 
the heat pipes approach or reach operating temperature. 
Once operating the heat pipes 32 improve flame stabil- 
ity and improve the turndown ratio of the combustor. 
1. A combustor comprising an air flow inlet and an 
outlet, a fuel supply, a plurality of mixing chambers 
disposed in said combustor, a fuel inlet manifold for 
2o providing fuel at respective inlets of said mixing cham- 
bers, said chambers being in the path of air from said air 
flow inlet, a portion of the air from said air flow inlet 
bypassing said mixing chambers, a plurality of heat 
pipes each having one portion in the path of the fuel and 
25 air as it is mixed in a respective one of said mixing cham- 
bers and another portion downstream of said mixed air 
fuel adjacent the zone of combustion during operation, 
thereby in operation to transfer heat of combustion 
upstream of enhance fuel vaporization and complete 
2. A combustor as claimed in claim 1, said combustor 
having walls, and a liner between said walls and said 
combustion zone, said liner and air inlet being arranged 
so that air is supplied to a passageway between said 
3. A combustor as claimed in claim 2, said liner hav- 
ing one or more apertures arranged to supply air from 
said passageway to said combustion zone, thereby to 
supply air to a dilution zone about said combustion zone 
l5 What is claimed is: 
30 combustion. 
35 walls and said liner. 
40 to improve combustion. * * * * *  
45 
50 
55 
60 
65 


Fuel combustor

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