A fuel injection array for a gas turbine engine includes a plurality of bluff body injectors and a plurality of swirler injectors. A control operates the plurality of bluff body injectors and swirler injectors such that bluff body injectors are utilized without all of the swirler injectors at least at low power operation. The swirler injectors are utilized at higher power operation

Snyder, Timothy S.

NASA Technical Reports Server

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(12) United States Patent 
Snyder 
(54) GAS TURBINE ENGINE STAGED FUEL 
INJECTION USING ADJACENT BLUFF BODY 
AND SWIRLER FUEL INJECTORS 
(75) Inventor: Timothy S. Snyder, Glastonbury, CT 
(US) 
(73) Assignee: United Technologies Corporation, 
Hartford, CT (US) 
(*) Notice: 	 Subject to any disclaimer, the term of this 
patent is extended or adjusted under 35 
U.S.C. 154(b) by 832 days. 
(21) Appl. No.: 13/170,406 
(22) Filed: 	 Jun. 28, 2011 
(65) 	 Prior Publication Data 
US 2013/0000311 Al 	 Jan. 3, 2013 
(51) Int. Cl. 
F02C 71228 	 (2006.01) 
F23R 3134 	 (2006.01) 
F23R 3114 	 (2006.01) 
(52) U.S. Cl. 
CPC . F23R 31343 (2013.01); F23R 3114 (2013.01); 
F23D 2900100015 (2013.01) 
USPC .................................. 60/749; 60/746; 60/748 
(58) Field of Classification Search 
USPC ............................ 60/737, 740, 746, 748, 749 
See application file for complete search history. 
(56) 	 References Cited 
U.S. PATENT DOCUMENTS 
5,099,644 A * 	 3/1992 Sabla et al 	 . ..................... 60/207 
5,142,858 A * 	 9/1992 Ciokajloetal . ................ 60/733  
(1o) Patent No.: 	 US 8,950,189 B2 
(45) Date of Patent: 	 Feb. 10, 2015 
5,207,064 A * 5/1993 Ciokajloetal . 	 ................ 60/737 
5,402,634 A 4/1995 Marshall 
5,551,869 A 9/1996 Brais et al. 
5,943,866 A 8/1999 Lovett et al. 
6,176,087 131 1/2001 Snyder et al. 
6,295,801 131 * 10/2001 Burrus et al . 	 ................... 60/776 
6,481,209 131 * 11/2002 Johnson et al . 	 ................. 60/746 
7,412,833 132 8/2008 Widener 
7,621,132 132 11/2009 Cornwell et al. 
2002/0112482 Al 8/2002 Johnson et al. 
2009/0151360 Al * 6/2009 Burd et al . 	 ...................... 60/748 
2010/0050644 Al 3/2010 Pidcock et al. 
2011/0185735 Al* 8/2011 Snyder 	 ............................ 60/746 
OTHER PUBLICATIONS 
European Search Report dated Oct. 22, 2012, from EP Appl. 
12173923.9-2301. 
* cited by examiner 
Primary Examiner Ehud Gartenberg 
Assistant Examiner Lorne Meade 
(74) Attorney, Agent, or Firm Carlson, Gaskey & Olds, 
PC 
(57) 	 ABSTRACT 
A fuel injection array for a gas turbine engine includes a 
plurality of bluff body injectors and a plurality of swirler 
injectors. A control operates the plurality of bluff body injec-
tors and swirler injectors such that bluff body injectors are 
utilized without all of the swirler injectors at least at low 
power operation. The swirler injectors are utilized at higher 
power operation. 
11 Claims, 3 Drawing Sheets 
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https://ntrs.nasa.gov/search.jsp?R=20150003451 2019-08-31T11:42:58+00:00Z
U.S. Patent 	 Feb. 10, 2015 	 Sheet 1 of 3 	 US 8,950,189 B2 
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U.S. Patent 	 Feb. 10 , 2015 	 Sheet 2 of 3 	 US 8 ,950,189 B2 
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U.S. Patent 	 Feb. 10, 2015 	 Sheet 3 of 3 	 US 8,950,189 B2 
US 8,950,189 B2 
GAS TURBINE ENGINE STAGED FUEL 
INJECTION USING ADJACENT BLUFF BODY 
AND SWIRLER FUEL INJECTORS 
This invention was made with government support under 
Contract No. NNCOSCA92C by NASA. The Government has 
certain rights in this invention. 
BACKGROUND 
This application relates to a fuel injection apparatus and 
method for use in a gas turbine engine, where both bluff body 
injectors, and swirler injectors are utilized in stages. 
Gas turbine engines are known, and typically include a 
compressor compressing air and delivering the air to be 
mixed with fuel in a combustion chamber, and then ignited. 
The amount and ratio of fuel and air which are mixed and 
ignited vary. At low power, a fuel/airratio is low, and at higher 
power, such as take-off and cruise, the fuel/air ratio is higher. 
It is known to control a group of injectors in stages, with some 
injectors not being utilized during low power operation, and 
then utilized at higher power operation. 
Fuel injectors are known which utilize a swirler concept. In 
a swirler concept, the fuel is injected into a swirling chamber, 
and mixed with air prior to combustion. 
Another type of injector is a so-called bluff body injector, 
which directly injects fuel into a combustion chamber. 
SUMMARY 
A fuel injection array for a gas turbine engine includes a 
plurality of bluff body injectors and a plurality of swirler 
injectors. A control operates the plurality of bluff body injec-
tors and swirler injectors such that bluff body injectors are 
utilized without all of the swirler injectors at least at low 
power operation. The swirler injectors are utilized at higher 
power operation. 
These and other features of the present invention can be 
best understood from the following specification and draw-
ings, of which the following is a brief description. 
BRIEF DESCRIPTION OF THE DRAWINGS 
FIG. 1 schematically shows a gas turbine engine. 
FIG. 2 schematically shows a fuel injector array according 
to this application. 
FIG. 3 shows one portion of the FIG. 2 array. 
FIG. 4 shows another portion. 
FIG. 5 is a cross-sectional view along line 5-5 of FIG. 4. 
FIG. 6 shows the combined operation of the FIG. 2 array. 
FIG. 7 shows an alternative embodiment. 
FIG. 8 is a view along line 8-8 of FIG. 7. 
FIG. 9 shows another alternative embodiment. 
DETAILED DESCRIPTION 
A gas turbine engine 10, such as a turbofan gas turbine 
engine, circumferentially disposed about an engine center-
line, or axial centerline axis 12 is shown in FIG. 1. The engine 
10 includes a fan 14, compressor sections 15 and 16, a com-
bustion section 18 and a turbine section 20. As is well known 
in the art, air compressed in the compressor 15/16 is mixed 
with fuel and burned in the combustor 18 and expanded in 
turbine 20. The turbine 20 includes rotors 22 and 24, which 
rotate in response to the expansion. The turbine 20 comprises 
alternating rows of rotary airfoils or blades 26 and static 
airfoils or vanes 28. In fact, this view is quite schematic, and 
2 
blades 26 and vanes 28 are actually removable. It should be 
understood that this view is included simply to provide a basic 
understanding of the sections in a gas turbine engine, and not 
to limit the invention. This invention extends to all types of 
5 turbine engines for all types of applications. 
FIG. 2 shows a fuel injection array 40 which can be utilized 
with the combustor 18 in a gas turbine engine. As shown, a 
plurality of bluff body injectors 44 are circumferentially 
interspaced with swirler injectors 42. In one embodiment, 
to there may be 16 of each type of injectors spaced around a 
central axis X of the gas turbine engine. Of course, other 
numbers can be used. 
Swirlers are generally known, and one such device is 
15 shown in FIG. 3. As shown in FIG. 3, the swirler injector 42 
includes a fuel injection pipe 46 injecting fuel into a swirler 
body 48. Swirlers are designed to provide air to mix with the 
fuel, such that the fuel and air are well mixed when they reach 
a combustion chamber 50. As shown, igniter 81 ignites the 
20 mixed fuel and air in the combustion chamber 50. 
FIG. 4 shows a bluff body injector 44. A tube 54 receives 
fuel and directs the fuel outwardly to a pilot port 56. Pilot 
opening 56 generally injects fuel into the combustion cham-
ber 50. The pipe 54 also has a plurality of openings 58 which 
25 inject fuel into an air flow passages 52. As can be appreciated 
from FIG. 5, the air flow passages 52 may be on both sides of 
the pipe 54, with the injection 58 moving into the air flow 
passages 52 and being mixed prior to reaching the combus-
tion chamber 50. As shown, the pilot opening 56 injects the 
so fuel directly into the combustion chamber 50. 
FIG. 6 shows a well mixed fuel/air zone which is provided 
when all of the injectors 42, 44 are being utilized. As shown, 
the pipes 54 have pilot openings 56 injecting fuel and having 
a recirculating area 86. The pilot opening 56 provides a very 
35 stable and reliable flame. 
Fuel is injected outwardly through ports 58 and into the air 
flow passages 52 creating a portion of well mixed zone 100. 
The flame is held in the zones 86 and 84 which are relatively 
low velocity regions of the flame. 
40 	 The swirler 42 is shown creating the other portion of well 
mixed fuel/air zone 100. The flame is held in zones 82 from 
the injected fuel 80. 
Returning to FIGS. 3 and 4, a control 300 is shown sche-
matically associated with the pipe 54 and the fuel injector 46. 
45 The control 300 is operable to supply or block supply of fuel 
to the pipe 54 and the injector 46. 
The injector array 40 is utilized in stages. Under low power 
operation, a first stage defined by the pilot openings 56 is 
utilized in combination with a second stage which is defined 
5o by the flow through the ports 58. Thus, at idle, taxi, or sub-
cruise operation, fuel is blocked through the swirlers 42 by 
the control 300. 
At take-off and cruise, a third stage is utilized in combina-
tion with the first two stages. The third stage includes the 
55 swirlers 42. 
The bluff body injector is particularly advantageous at 
lower power operation, as it provides the stable and reliable 
flame. A swirler is not as efficient at lower volume flow. 
On the other hand, using the several types of injectors at 
6o higher power provides benefits in that the swirlers provide 
excellent mixing. Further, the second stage injection would 
also provide good mixing. The use of the several distinct 
types of injection results in an overall combustion pattern that 
is not a coherent structure. If only a single type of injector is 
65 utilized, then the resultant combustion could act as a coherent 
structure, and result in an audio tone, which would be unde-
sirable. 
US 8,950,189 B2 
3 
FIG. 7 shows another embodiment bluff body 90. As 
shown, the fluid pipe 92 includes a central passage 94 leading 
to the pilot opening 104. Side ports 96 operate as in earlier 
embodiments. Additional ports 98 supply fuel outwardly at a 
location upstream from the ports 96. Air flow 102 mixes with 
all of the fuel from the ports 98 and 96, and then penetrates 
and mixes into air passages 52 to create a well mixed fuel/air 
zone 100. 
As can be appreciated from FIG. 8, there area great number 
of ports 98, ensuring increased mixing of the fuel with air 102 
and 52. 
The use of the bluffbody injector, and in particular the pilot 
opening ensures efficient and reliable combustion at the lower 
power operations On the other hand, the use of the swirler 
injectors at higher power operation ensure reduced smoke, or 
NOx emissions. 
At lower power operation, the amount of fuel flow in stage 
2 is much greater than the amount of fuel flow from stage 1. At 
mid to high power operation, the amount of fuel flow from 
stage 3 can be optimized for emissions and combustion 
dynamics. The amount of fuel flow from stage 1. 
FIG. 9 shows an embodiment 200 of a swirler wherein a 
first supply of fuel 202 extends to a location radially out-
wardly of the main injection point 204 to increase the level of 
fuel/air mixing. Air mixes withthis fuel in the swirlerbody, as 
known. 
Although embodiments of this invention have been dis-
closed, a worker of ordinary skill in this art would recognize 
that certain modifications would come within the scope of thi s 
invention. For that reason, the following claims should be 
studied to determine the true scope and content of this inven-
tion. 
What is claimed is: 
1. A fuel injection array for a gas turbine engine compris-
ing: 
a plurality of bluff body injectors and a plurality of swirler 
injectors; 
a control for operating said plurality of bluff body injectors 
and said swirler injectors such that said bluff body inj ec-
tors are utilized without all of the swirler injectors at 
least at low power operation, and said swirler injectors 
are utilized at higher power operation; and 
said bluff body injectors include a central flow passage 
leading to a pilot port communicating fuel directly into a 
combustion chamber, said bluff body injectors also com-
municate fuel into locations upstream of the combustion 
chamber where the fuel is mixed with air prior to it 
reaching the combustion chamber, a fuel supply line 
leads into said central flow passage, and ports extend 
4 
from said fuel supply line to locations on opposed sides 
of said central flow passage to intermix with air flowing 
along said opposed sides. 
2. The fuel injection array as set forth in claim 1, wherein 
5 said bluff body injectors are utilized along with said swirler 
injectors at higher power operation. 
3. The fuel injection array as set forth in claim 1, wherein 
fuel is directed in a plurality of directions from said ports. 
4. The fuel injection array as set forth in claim 1, wherein 
10 
fuel is directed from said fluid supply line into said ports at a 
plurality of locations including locations spaced more 
upstream from others of said locations. 
5. The fuel injection array as set forth in claim 1, wherein 
said swirler injectors including a fuel injector delivering fuel 
at a radially outer location and a radially inner location. 
15 6. The fuel injection array as set forth in claim 1, wherein 
saidbluffbody injectors and said swirler injectors are circum-
ferentially interspaced about a central axis. 
7. The fuel injection array as set forth in claim 1, wherein 
said control controlling the flow of fuel to said bluff body 
20 injectors and said swirler injectors. 
8. A fuel injection array for a gas turbine engine compris-
ing: 
a plurality of bluff body injectors and a plurality of swirler 
injectors; 
25 	 a control for operating said plurality of bluff body injectors 
and said swirler injectors such that said bluff body injec-
tors are utilized without all of the swirler injectors at 
least at low power operation, and said swirler injectors 
are utilized with said bluff body injectors at higher 
30 	 power operation; 
said bluff body injectors include a central flow passage 
leading to a pilot port communicating fuel directly into a 
combustion chamber, said bluff body injectors also com-
municate fuel into locations upstream of the combustion 
35 chamber where the fuel is mixed with air prior to it 
reaching the combustion chamber; and 
said bluff body injectors and said swirler injectors are 
circumferentially interspaced about a central axis. 
9. The fuel injection array as set forth in claim 8, wherein a 
40 fuel supply line leads into said central flow passage, and ports 
extend from said fuel supply line to locations on opposed 
sides of said central flow passage to intermix with air flowing 
along said opposed sides. 
10. The fuel injection array as set forth in claim 9, wherein 
45 fuel is directed in a plurality of directions from said ports. 
11. The fuel injection array as set forth in claim 9, wherein 
fuel is directed from said fluid supply line into said ports at a 
plurality of locations including locations spaced more 
upstream from others of said locations. 


Gas Turbine Engine Staged Fuel Injection Using Adjacent Bluff Body and Swirler Fuel Injectors

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