CROSS-REFERENCE TO RELATED APPLICATIONS
The current application claims priority to U.S. Provisional Application, Ser. No. 61/569,904, filed
December 13, 2011, the entire disclosure of which is incorporated herein by reference.
BRIEF DESCRIPTION OF THE DRAWINGS
The system for aerodynamically enhanced premixer for reduced emissions may be best understood
by reference to the following description taken in conjunction with the accompanying drawing
figures in which:
Figure 1 is a schematic illustration of a gas turbine engine including a combustor
Figure 2 is a cross-sectional view illustration of a gas turbine engine combustor with an
exemplary embodiment of an aerodynamically enhanced premixer.
Figure 3 is an enlarged cross-sectional view illustrating selected details of a fuel nozzle and
the premixer of Figure 2.
Figure 4a is an enlarged cross-sectional view illustrating selected details of an alternative
fuel nozzle and premixer.
Figure 4b is an enlarged cross-sectional view illustrating selected details of another
alternative fuel nozzle and premixer.
Figure 5 is a perspective view of an aerodynamically enhanced premixer.
Figure 6 is another perspective view of the aerodynamically enhanced premixer of Figure 5.
Figure 7 is a cross-sectional view showing selected details of the aerodynamically enhanced
premixer of Figure 5.
Figures 8 - 9,10 -11,12 -13a, 14 -15,16 -17,18 -19,20 - 21,22 - 23,24 - 25,28 - 29,
and 30 - 31 provide a pair of views, the first view of each pair shown in perspective and the second
view of each pair in sectional, each pair of views so chosen to illustrate selected details of alternative
embodiments of an aerodynamically enhanced premixer.
Figures 13b and 13c illustrate selected details for purge slots of an aerodynamically
enhanced premixer.
Figures 2Ga, 2Gb, and 27 provide a set of three views, the first view shown in perspective,
the second view in another perspective and the third view in sectional, the set of views chosen to
illustrate selected details for chevron splitters of alternative embodiments of an aerodynamically
enhanced premixer.
BACKGROUND AND PROBLEM SOLVED
Embodiments and alternatives are provided of a premixer that improves fuel efficiency while
reducing exhaust gas emissions. Embodiments include those wherein a boundary layer profile over
the fuel nozzle (center-body) is controlled to minimize emissions. In the past, it has been difficult to
increase flow velocity at the flow boundary layer while also sizing components properly to achieve
optimum vane shape in a premixer as well as positioning swirlers within the combustor system
closer together. As such, embodiments and alternatives are provided that achieve accurate control
of boundary layer profile over the fuel nozzle (center-body) by utilizing mixer-to-mixer proximity
reduction, premixer vane tilt to include the use of compound angles, reduced nozzle/mixer tilt
sensitivity, and mixer foot contouring. Additional boundary layer control is realized using purge
slots, placed on either or both of the premixer foot or the nozzle outer diameter, and a splitter when
employed with a twin radial mixer.
MULTIPLE EMBODIMENTS AND ALTERNATIVES
By way of general reference, aircraft gas turbine engine staged combustion systems have
been developed to limit the production of undesirable combustion product components such as
oxides of nitrogen (NOx), unburned hydrocarbons (HC), and carbon monoxide (CO) particularly in the
vicinity of airports, where they contribute to urban photochemical smog problems. Gas turbine
engines also are designed to be fuel efficient and to have a low cost of operation. Other factors that
influence combustor design are the desires of users of gas turbine engines for efficient, low cost
operation, which translates into a need for reduced fuel consumption while at the same time
maintaining or even increasing engine output. As a consequence, important design criteria for
aircraft gas turbine engine combustion systems include provisions for high combustion
temperatures, in order to provide high thermal efficiency under a variety of engine operating
conditions. Additionally, it is important to minimize undesirable combustion conditions that
contribute to the emission of particulates, and to the emission of undesirable gases, and to the
emission of combustion products that are precursors to the formation of photochemical smog.
One mixer design that has been utilized is known as a twin annular premixing swirler (TAPS),
which is disclosed in the following U.S. Patent Nos. 6,354,072; 6,363,726; 6,367,262; 6,381,964;
6,389,815; 6,418,726; 6,453,660; 6,484,489; and, 6,865,889. It will be understood that the TAPS
mixer assembly includes a pilot mixer which is supplied with fuel during the entire engine operating
cycle and a main mixer which is supplied with fuel only during increased power conditions of the
engine operating cycle. While improvements in the main mixer of the assembly during high power
conditions (Le., take-off and climb) are disclosed in patent applications having Serial Nos.
11/188,596,11/188,598, and 11/188,470, modification of the pilot mixer is desired to improve
operability across other portions of the engine's operating envelope (Le., idle, approach and cruise)
while maintaining combustion efficiency. To this end and in order to provide increased functionality
and flexibility, the pilot mixer in a TAPS type mixer assembly has been developed and is disclosed in
U.S. Patent No. 7,762,073, entitled "Pilot Mixer For Mixer Assembly Of A Gas Turbine Engine
Combustor Having A Primary Fuel Injector And A Plurality Of Secondary Fuel Injection Ports" which
issued July 27, 2010. This patent is owned by the assignee of the present application and hereby
incorporated by reference.
United States Patent Application No. Serial No. 12/424,612 (PUBLICATION NUMBER
20100263382), filed April 16, 2009, entitled "DUAL ORIFICE PILOT FUEL INJECTOR" discloses a fuel
nozzle having first second pilot fuel nozzles designed to improve sub-idle efficiency, reduced
circumferential exhaust gas temperature (EGT) variation while maintaining a low susceptibility to
coking of the fuel injectors. This patent application is owned by the assignee of the present
application and hereby incorporated by reference.
Figure 1 is provided as an orientation and to illustrate selected components of a gas turbine
engine 10 which includes a bypass fan 15, a low pressure compressor 300, a high pressure
compressor 400, a combustor 16, a high pressure turbine 500 and a low pressure turbine 600.
With reference to Figure 2, illustrated is an exemplary embodiment of a combustor 16
including a combustion zone 18 defined between and by annular radially outer and inner liners 20, 22,
respectively circumscribed about an engine centerline 52. The outer and inner liners 20, 22 are
located radially inwardly of an annular combustor casing 26 which extends circumferentially around
outer and inner liners 20,22. The combustor 16 also includes an annular dome 34 mounted upstream
of the combustion zone 18 and attached to the outer and inner liners 20, 22. The dome 34 defines an
upstream end 36 of the combustion zone 18 and a plurality of mixer assemblies 40 (only one is
illustrated) are spaced circumferentially around the dome 34. Each mixer assembly 40 includes a
premixer 104 mounted in the dome 34 and a pilot mixer 102.
The combustor 16 receives an annular stream of pressurized compressor discharge air 402
from a high pressure compressor discharge outlet 69 at what is referred to as CDP air (compressor
discharge pressure air). A first portion 23 of the compressor discharge air 402 flows into the mixer
assembly 40, where fuel is also injected to mix with the air and form a fuel-air mixture 65 that is
provided to the combustion zone 18 for combustion. Ignition of the fuel-air mixture 65 is
accomplished by a suitable igniter 70, and the resulting combustion gases 60 flow in an axial direction
toward and into an annular, first stage turbine nozzle 72. The first stage turbine nozzle 72 is defined
by an annular flow channel that includes a plurality of radially extending, circularly-spaced nozzle
vanes 74 that turn the gases so that they flow angularly and impinge upon the first stage turbine blades
(not shown) of a first turbine (not shown).
The arrows in Figure 2 illustrate the directions in which compressor discharge air flows
within combustor 16. A second portion 24 of the compressor discharge air 402 flows around the outer
liner 20 and a third portion 25 of the compressor discharge air 402 flows around the inner liner 22. A
fuel injector 11, further illustrated in FIG. 2, includes a nozzle mount or flange 30 adapted to be fixed
and sealed to the combustor casing 26. A hollow stem 32 of the fuel injector 11 is integral with or
fixed to the flange 30 (such as by brazing or welding) and includes a fuel nozzle assembly 12. The
hollow stem 32 supports the fuel nozzle assembly 12 and the pilot mixer 102. A valve housing 37 at
the top of the stem 32 contains valves illustrated and discussed in more detail in United States Patent
Application No. 20100263382, referenced above.
Referring to Figure 2 and with further details shown in Figure 3, the fuel nozzle assembly 12
includes a main fuel nozzle 61 and an annular pilot inlet 54 to the pilot mixer 102 through which the
first portion 23 of the compressor discharge air 14 flows. The fuel nozzle assembly 12 further
includes a dual orifice pilot fuel injector tip 57 substantially centered in the annular pilot inlet 54. The
dual orifice pilot fuel injector tip 57 includes concentric primary and secondary pilot fuel nozzles 58,
59. The pilot mixer 102 includes a centerline axis 120 about which the dual orifice pilot fuel injector
tip 57, the primary and secondary pilot fuel nozzles 58, 59, the annular pilot inlet 54 and the main fuel
nozzle 61 are centered and circumscribed.
A pilot housing 99 includes a centerbody 103 and radially inwardly supports the pilot fuel
injector tip 57 and radially outwardly supports the main fuel nozzle 61. The centerbody 103 is
radially disposed between the pilot fuel injector tip 57 and the main fuel nozzle 61. The centerbody
103 surrounds the pilot mixer 102 and defines a chamber 105 that is in flow communication with, and
downstream from, the pilot mixer 102. The pilot mixer 102 radially supports the dual orifice pilot
fuel injector tip 57 at a radially inner diameter ID and the centerbody 103 radially supports the main
fuel nozzle 61 at a radially outer diameter OD with respect to the engine centerline 52. The main fuel
nozzle 61 is disposed within the premixer 104 (See Fig. 1) ofthe mixer assembly 40 and the dual
orifice pilot fuel injector tip 57 is disposed within the pilot mixer 102. Fuel is atomized by an air
stream from the pilot mixer 102 which is at its maximum velocity in a plane in the vicinity of the
annular secondary exit 100.
With reference to Figures 4a and 4b, embodiments and alternatives are provided having an
airstream passage being a nozzle slot 62 disposed within the structure of the nozzle 61 thereby
allowing fluid communication between selected structure of the fuel injector 11. Selected structure
includes but is not limited to the hollow stem 32.
Turning our attention to the premixer 104 and with reference to Figure 3 and also to Figures
5 - 9, the premixer 104 is generally cylindrical in form and is defined by the relationship in physical
space between a first ring 200, a second ring 220, and a plurality of radial vanes 210. In further
detail, embodiments include those wherein the first and second rings 200, 220 are found to be
generally equidistant, one from the other, at all points along their facing surfaces. If the first ring
200 is considered to lie largely within a single plane, then the second ring 220 is offset in physical
space such that the plane it occupies is general parallel to the plane of the first ring 200. By
continued reference to the figures, it can then be seen that the radial vanes 210 connect the first
ring 200 to the second ring 220 and thereby form the premixer 104.
Alternatives are provided for which the generally equidistant and parallel-plane nature of
the rings 200, 220 is not required. For such embodiments the rings 200, 220 are contemplated to
not be disposed in generally parallel planes.
Additional embodiments and alternatives provide premixers 104 having a variety of
additional structure, cavities, orifices and the like selectably formed or provided, as desired in order
to provide enhanced fuel efficiency along with reduced emissions in combustion. Several
alternatives have been selected for illustration in Figures 8 - 31; however, the embodiments
illustrated are intended to be viewed as exemplars of a much wider variety of embodiments and
alternatives.
7
With reference once more to Figures 3 and 7, alternatives include those wherein first ring
200 has a first ring outer diameter and a first ring inner diameter as generally measured at first outer
point 202 and first inner point 204, respectively. With specific reference to Figure 3, a portion of
the first ring 200 is illustrated as first inner ring platform 205. A first inner shoulder 206 and a first
outer shoulder or "foot" 208 are found on some embodiments. The second ring 220 has a second
ring outer diameter and a second ring inner diameter as generally measured at second outer point
222 and second inner point 224, respectively. A second inner shoulder 226 is located at a point,
viewed in cross section, where the structure of second ring 220 moves through a generally right
angle thereby forming a chamber 228 being generally cylindrical in alternative embodiments. One
or more aft lip purge flow openings 227 are formed and disposed on ring 220, as desired. The
chamber 228 is disposed in the main mixer 104 generally apart from a region of the main mixer 104
where the vanes 210 are located.
Recall that (see Fig. 2) the first portion 23 of the compressor discharge air 14 flows into the
mixer assembly 40, being fluid compressed upstream in a compressor section (not shown) of the
engine and routed into the combustor system. Such air 14 arrives from outside the mixer assembly
40 passing inward and being routed through the mixer 40 along shoulder 226 and onward through
chamber 228 exiting to become a portion of fU,el-air mixture 65.
By selectably altering the values for the respective diameters and distances between various
elements of the pre mixer 104 so defined above, and as shown in Figures 7 - 31, embodiments are
provided that present selected and desired physical structure into the flow path to optimize flow
through the premixer 104. For example, premixers 104 as exemplified in Figs. 5 - 9 provide
generally for a longer chamber 228 than prior designs, thereby providing higher bulk axial velocity.
Figure 8 shows a perspective view of an embodiment and Figure 9 shows a sectional view of
that same embodiment. The succeeding pairs of Figures: 10 -11,12 -13, and so on, through
Figure pair 30 and 31, provide those views, each pair for a different illustrative embodiment and
alternative premixer 104. Figure set 26a - 26c uses three views to illustrate details for alternatives
that include a splitter 240. For succeeding figures that also include a waveform 242, reference is
directed back to Figs. 26a - 26c for splitter 240 details.
With reference to Figs. 10 -19 premixers exemplified provide for the addition of purge slots
230 to the structure of those premixers 104 as exemplified in Figs. 5 - 9. These slots 230 assist in
energizing the boundary layer on the centerbody 103 (see Fig. 4).
With reference to Fig. 13a and also shown in Figure 17, alternative premixers 104 include a
tilt angle 700 provided as follows:
It can be seen that if the first inner point 204 is displaced axially inward into the main mixer
104 as compared to the location of the first outer point 202, then the shoulder 206 is also found to
be incorporated into embodiments so formed. If the shoulder 206 is generally co-located with first
outer point 202, then a generally sloping contour is presented along an inner surface of first ring
200.
In cross-sectional view (see Figs. 13 and 17), the tilt angle 700 is readily seen as measured
between a line tracing the generally sloping contour along the inner surface of first ring 200 and a
line drawn radially outward from a centerline of the injector 11. Alternatives are provided that have
t the shoulder disposed at some location inboard from first outer point 202 and consequently closer
to first inner point 204. By reference to the cross-sectional view, the tilt is presented to the air 14 as
it arrives into the premixer 104. Such tilt 700 assists in enhancing the efficiency and reducing
aerodynamic losses associated with providing a flow 14 pattern with reduced changes in angular
direction when viewed from the side in cross section. Such an aerodynamic package results in
enhanced boundary layer control, improved proximity and reduced stack sensitivity. The means for
tilt 700 provides control of boundary layer, optimizes swirler packaging, provides robust mixing by
reducing eccentricity and allows for reduction in the size of the mixer cavity 228.
With reference to Figures 10 - 23, embodiments and alternatives provide for second ring
220 being formed separately from premixer 104 wherein second ring 220 is mated to corresponding
structure, the associated two - part assembly thereby becoming premixer 104.
Figures 10 - 27 also illustrate embodiments and alternatives having a plurality of purge slots
230 disposed as desired and formed within first ring 200.
Figures 26a - 31 provide exemplars of premixer 104 embodiments for which one or more
splitters 240 are provided, disposed generally within the vanes 210. Such embodiments provide
enhanced aerodynamic efficiency of flow 14. In addition, alternatives exemplified in Figs. 26a - 31
_ also include a waveform 242 formed and disposed upon the splitter 240 in order to further enhance
the aerodynamic efficiency of flow 14.
With reference to Figs. 18 - 23, premixers exemplified provide for a shorter premixer 104
with concurrently shorter radial vanes 210 and having a longer chamber 228 wherein an inner peak
velocity profile is maximized.
With reference to Figs. 26a - 31, premixers exemplified provide for further distinctions over
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alternative premixers 104.
Specifically, with reference to Figs. 26a, 26b and 27, in addition to the radial vanes 210 of
alternatives exemplified in other Figures, conical vanes 212 are formed generally upon the first ring
200 and depending radially inward therefrom. In addition, the one or more splitters 240 are
provided generally radially inboard of a shorter premixer 104 with concurrently shorter radial vanes
210 and haVing a longer chamber 228 wherein an inner peak velocity profile is maximized.
With reference to Figs. 28 - 31, the one or more splitters 240 are located axially between the
first ring 200 and the second ring 220 and interposed along the length of what has been heretofore
shown as the radial vane 210 of other alternatives (See, for example, Figs. 26a, 26b and 27). As such,
the embodiments exemplified in Figs. 28 - 31 replace the radial vane 210 with two radial vanes: a
forward radial vane 216 disposed between the first ring 200 and the splitter 240, and an aft radial
vane 214 disposed between the splitter 240 and the second ring 220. Such embodiments are shown
to enhance low emission operation while also raising the potential for dynamic air flow. Other
embodiments provide that in place of one or more of the radial vanes 210, the one or more conical
vanes 212 are formed generally upon the first ring and depending radially inward therefrom.
Further embodiments provide the waveform 242 disposed upon the splitter 240 thereby
further enhancing low emission operation while also raising the potential for dynamic air flow.
Some waveforms 242 are formed in the shape of a chevron. With respect to vanes 210, forward
radial vanes 216 and aft radial vanes 214, as found on any particular embodiment, some alternatives
provide for abrupt profile changes along a surface path as seen in viewing a transition from structure
nearby but apart from these vanes 210, 214, 216. For example, in some embodiments, the vanes
210, 214, 216 are formed by stamping or other operations involving cutting and bending. In further
detail with respect to this example not meant to be limiting, embodiments include those that show
vanes having approximately 90 degree angles of transition corresponding to a transition radius being
very close to zero - blunt edges, more or less. Alternatives include those wherein the vanes 210,
214, 216 feature a less abrupt transition, that transition being instead a radiused transition. The
transition radius for such vanes 210, 214, 216 is an inlet radius 211. Alternatives include those
• wherein the inlet radii 211 are within a range of from 0.010 inches to 0.030 inches. Even further
alternatives feature both abrupt and radiused transitions with respect to the vanes 210, 214, 216.
Referring back to the nozzle 61 with details shown in Figures 3, 4a and 4b, embodiments and
alternatives of premixers 104 are provided wherein additional boundary layer control is realized
using slots to include purge slots 230 and/or nozzle slots 62 disposed at either or both of the foot
208 of the premixer 104 or along an outer diameter of the nozzle 61, respectively. With reference to
Figure 4b, alternatives include those wherein the air stream passages are formed as more than one
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nozzle slot 62 allowing additional air to pass through the nozzle 61 in proximity to but radially inward
from the foot 208 of the premixer 104.
For embodiments having purge slots 230 and with reference to Figs. 13, 13b and 13c,
alternatives provide for the purge slots to be formed in geometries that incorporate either, both, or
none of a radial angle 232 (as shown in Fig. 13) and a circumferential angle 234. With regard to the
circumferential angle 234 and with reference to Figs. 13b and 13c, a plane 236 is shown in a
perspective view of the premixer 104 in Fig. 13b. It is with reference to the plane 236 in Fig. 13c that
the circumferential angle 234 is seen. The viewpoint of Fig. 13c is within the plane 236, therefore
the plane 236 appears to be a vertical line from 6 o'clock to 12 o'clock in that view. The
circumferential angle 234 is taken from plane 236 to a line extending along the face of a selected
structural portion within the purge slot 230 as shown in Fig. 13c. Alternatives include those wherein
the radial angle is within a range of from about 0 degrees to about 45 degrees. Alternatives include
those wherein the circumferential angle is within a range of from about 0 degrees to about 60
degrees. Embodiments include those wherein a count of all purge slots is the same as a count of all
vanes.
Alternatives provide for selected disposition or alignment of the purge slots 230. For
example, with reference to Figs. 15 and 16, alternatives provide that the purge slots 230 discharge
within an area that illustrated as in-between the first inner point 204 and the first inner shoulder
206. With reference to Figs. 16 and 17, other embodiments provide instead that the purge slots 230
discharge not within an area defined by the first inner point 204 and the first inner shoulder 206 but
instead, the purge slots 230 discharge radially further inward and thereby along the first inner ring
platform 205.
Other alternatives provide for circumferential purge by other selections for alignment of the
purge slots 230. Embodiments also provide for variable axial purge by selections for alignment of
the purge slots 230 and also by selection of shape of the first ring 200 to include shape and location
1<2--
of first outer shoulder 208. Purge slots 230 provide for localized boundary layer control. When
combined with a tilt angle 700, purge slots 230 also provide a focused and energized boundary layer.
When variable axial purge is utilized, the premixer 104 enjoys a reduction of sensitivity to leakage
variations sometimes seen circumferentially around the premixer 104. Variable axial purge also
allows for purge to be reduced at low power.
With reference to Figs. 18 and 20, alternatives provide that the purge slots 230 of Figure 18
may selectably grow in dimensions (see Fig. 20) to serve as one or more axial vanes. These axial
vanes may also serve as an embodiment ofthe conical vane shown in Figures 26a, 26b and 27.
Alternatives (see Figs. 26a, 26b and 27) provide that the one splitter 240 is located axially
between the first ring 200 and the second ring 220 and wherein one conical vane and one radial
vane are provided; being a forward conical vane disposed between the first ring 200 and the splitter
240 and an aft radial vane disposed between the splitter 240 and the second ring 220.
Embodiments and alternatives allow for selection of length of a throat of the premixer 104
as defined by the chamber 228. By dividing chamber length 228 over vane 210 length, a ratio of
those two values is determined. Embodiments provide enhanced flow and efficiency by selection
the ration within a desired range of values. Alternatives include those wherein the ratio of chamber
fI length 228 to vane 210 length is from 1:1 to 2:1. For example, and with reference to at least the
embodiment illustrated in Figures 20 - 21, alternatives (for example, see Figs. 18 -19 and 22 - 23)
include those wherein the vanes 210 are formed to be compact in relation to the chamber 228
thereby resulting in ratio values at a higher end of the range spectrum of 1:1 to 2:1. Such alternative
premixers 104 show significant reductions of NOx. Embodiments include those wherein NOx
reductions range from 10 to 20 percent.
With reference to Figs. 3,16 and 17, embodiments include those wherein thermal growth
and shrinkage is relied upon as a passive means to change relative position of the premixer 104 with
/'3>
respect to the fuel injector 11 thereby reducing non-uniformity of leakage gap velocity at high
power. In further detail, first ring inner platform 205 moves axially, in translating motion, with
respect to selected structure of the fuel injector 11 nozzle thereby opening or closing available area
between fuel injector 11 and platform 205 and consequently providing passive purge air control.
Proximity reduction refers to the possibility for locating a plurality of fuel nozzles, each
having a cup, within a combustor system in a desired arrangement thereby allowing a cup-to-cup
distance to be optimized. Alternatives provide for the cup-to-cup distance to be 0.100 inch or
greater. Tilt sensitivity refers to the possibility of repositioning the foot 208 radially downstream
with respect to other designs. Embodiments and alternatives are provided that allow a 10%
reduction in tilt sensitivity as seen by flow 14. As illustrated in at least Figure 14, a tilt angle 700
having a value generally in a range of between 10 to 45 degrees provides for increased velocity,
increased atomization and mixing of the air and fuel in flow 14, thereby providing measurable
enhancements by reducing inefficiency by a range of from 10% to 20%, along with reductions in
emissions.
While there have been described herein what are considered to be preferred and exemplary
embodiments of the present invention, other modifications of the invention shall be apparent to
those skilled in the art from the teachings herein, and it is, therefore, desired to be secured in the
appended claims all such modifications as fall within the true spirit and scope of the invention.

We Claim:
1. A system for Aerodynamically Enhanced Premixer for Reduced Emissions comprising:
A premixer being generally cylindrical in form and defined by the relationship in physical
space between a first ring, a second ring, and one or more radial vanes; wherein, the
first and second rings are found to be generally equidistant, one from the other, at all
points along their facing surfaces and the radial vanes connect the first ring to the
second ring and thereby form the premixer.
2. The system of claim 1, further comprising the first ring being considered to lie largely
within a single plane and the second ring being offset in physical space such that the
plane it occupies is generally parallel to the plane of the first ring.
3. The system of claim 1, further comprising the first ring being considered to lie largely
within a single plane and the second ring being offset in physical space such that the
plane it occupies is generally not parallel to the plane of the first ring.
4. The system of claim 1, further comprising the first ring having a first ring outer diameter
and a first ring inner diameter as generally measured at a first outer point and a first
inner point, respectively.
5. The system of claim 4, further comprising a first inner shoulder disposed inboard of the
radial vanes and a first outer shoulder disposed outboard of the radial vanes and
wherein the second ring has a second ring outer diameter and a second ring inner
diameter as generally measured at a second outer point and a second inner point,
respectively.
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6. The system of claim 5, f.urther comprising the a second inner shoulder being located at a
point, viewed in cross section, where the structure of second ring moves through a
generally right angle thereby forming a chamber being generally cylindrical.
7. The system of claim 6, further comprising one or more aft lip purge flow openings being
formed and disposed on the second ring.
8. The system of claim 6, further comprising the chamber being disposed in a main mixer
generally apart from a region of the main mixer where the radial vanes are located; and,
the radial vanes having inlet radii being within a range of from 0.010 inches to 0.030
inches.
9. The system of claim 6, further comprising one or more purge slots formed within the
first ring.
10. The system of claim 9, further comprising the one or more purge slots having a radial
angle defined thereupon and within a range of from about 0 degrees to about 45
degrees.
11. The system of claim 10, further comprising the one or more purge slots discharging
through a first ring inner platform.
12. The system of claim 10, further comprising the one or more purge slots having a
circumferential angle defined thereupon and within a range of from about 0 degrees to
about 60 degrees.
13. The system of claim 6, further comprising a tilt angle that is measured between a line
tracing a generally sloping contour along the inner surface of the first ring and a line
drawn radially outward from a centerline of the injector.
1(,
14. The system of claim 13, further comprising the shoulder disposed at a location inboard
from the first outer point and consequently closer in proximity to the first inner point.
15. The system of claim 9 wherein the purge slots grow in dimension to serve as axial vanes.
16. The system of claim 1, wherein the second ring is formed separately from the premixer
wherein the second ring is mated to corresponding structure, the associated two - part
assembly thereby comprising the premixer.
17. The system of claim 6, further comprising one or more splitters being provided, disposed
generally within the radial vanes.
18. The system of claim 17 further comprising a waveform formed and disposed upon the
splitters.
19. The system of claim 18, further comprising the one or more splitters being located
axially between the first ring and the second ring and wherein two radial vanes are
provided; being a forward radial vane disposed between the first ring and the splitter
and an aft radial vane disposed between the splitter and the second ring.
20. The system of claim 15, further comprising one or more splitters being provided,
disposed generally between the axial and radial vanes.
21. The system of claim 20 further comprising a waveform formed and disposed upon the
splitters.
22. The system of claim 17, further comprising that the one or more radial vanes are
replaced by one or more conical vanes being formed generally upon the first ring and
depending radially inward therefrom.
\1
23. The system of claim 22 further comprising a waveform formed and disposed upon the
splitters.
24. The system of claim 23, further comprising the one or more sptitters being located
axially between the first ring and the second ring and wherein one conical vane and one
radial vane are provided; being a forward conical vane disposed between the first ring
and the splitter and an aft radial vane disposed between the splitter and the second
ring.
25. The system of claim 6, wherein boundary layer control is realized using slots selected
from the group purge slots, nozzle slots; the slots being disposed at either or both of the
first outer shoulder of the premixer or along an outer diameter of the nozzle,
respectively.
26. The system of claim 25, wherein a count of purge slots is the same as a count of vanes.
27. The system of claim 6, wherein dividing a value for a chamber length by a value for a
vane length yields a ratio in a range of about 1:1 to about 2:1.
28. The system of claim 6, further comprising that NOx reductions range from 10 to 20
percent.
29. The system of claim 11, wherein thermal growth and shrinkage is relied upon as a
passive means to change relative position of the premixer with respect to the fuel
injector thereby reducing non-uniformity of leakage gap velocity at high power.
30. The system of claim 29 wherein the first ring inner platform moves axially, in translating
motion, with respect to selected structure of the fuel injector thereby opening or closing
available area between the fuel injector and the first ring inner platform and
consequently providing passive purge air control.
31. The system of claim 1, wherein the system includes one or more premixers affixed to a
like number of fuel nozzles and proximity reduction is realized by locating the one or fuel
nozzles, each having a cup, within a combustor system such that a cup-to-cup distance is
provided within a range of from about 0.100 inches or greater
32. The system of claim 8, further comprising a 10% reduction in tilt sensitivity as seen by a
flow.
33. The system of claim 13, further comprising the tilt angle having a value generally in a
range of between 10 to 45 degrees provides for increased velocity, increased
atomization and mixing of the air and fuel in the flow, thereby providing measurable
enhancements by reducing inefficiency by a range of from 10% to 20%, along with
reductions in emissions.
34. A system for Aerodynamically Enhanced Premixer for Reduced Emissions comprising:
A premixer being generally cylindrical in form and defined by the relationship in physical
space between a first ring, a second ring, and a plurality of radial vanes; wherein, the
first and second rings are found to be generally equidistant, one from the other, at all
points along their facing surfaces and radial vanes connect the first ring to the second
ring and thereby form the premixer;
Wherein the first ring is considered to lie largely within a single plane and the second
ring is offset in physical space such that the plane it occupies is generally parallel to the
plane of the first ring, and the first ring has a first ring outer diameter and a first ring
inner diameter as generally measured at a first outer point and a first inner point,
respectively;
a first inner shoulder is disposed inboard of the radial vanes and a first outer shoulder is
disposed outboard of the radial vanes and the second ring has a second ring outer
diameter and a second ring inner diameter as generally measured at a second outer
point and a second inner point, respectively, and the a second inner shoulder is located
at a point, viewed in cross section, where the structure of the second ring moves
through a generally right angle thereby forming a chamber being generally cylindrical;
further comprising one or more aft lip purge flow openings being formed and disposed
on the second ring, the chamber being disposed in a main mixer generally apart from a
region of the main mixer where the radial vanes are located, the radial vanes having
inlet radii being within a range of from 0.010 inches to 0.030 inches; and,
further comprising one or more purge slots formed within the first ring.
35. The system of claim 34; however, the first ring being considered to lie largely within a
single plane and the second ring being offset in physical space such that the plane it
occupies is generally not parallel to the plane of the first ring.
36. A system for Aerodynamically Enhanced Premixer for Reduced Emissions comprising:
A premixer being generally cylindrical in form and defined by the relationship in physical
space between a first ring, a second ring, and a plurality of radial vanes; wherein, the
first and second rings are found to be generally equidistant, one from the other, at all
points along their facing surfaces and the radial vanes connect the first ring to the
second ring and thereby form the premixer;
Wherein the first ring is considered to lie largely within a single plane and the second
ring is offset in physical space such that the plane it occupies is generally parallel to the
plane of the first ring, and the first ring has a first ring outer diameter and a first ring
inner diameter as generally measured at a first outer point and a first inner point,
respectively;
a first inner shoulder is disposed inboard of the radial vanes and a first outer shoulder is
disposed outboard of the radial vanes and the second ring has a second ring outer
diameter and a second ring inner diameter as generally measured at a second outer
point and a second inner point, respectively, and the a second inner shoulder is located
at a point, viewed in cross section, where the structure of the second ring moves
through a generally right angle thereby forming a chamber being generally cylindrical;
further comprising one or more aft lip purge flow openings being formed and disposed
on the second ring, the chamber being disposed in a main mixer generally apart from a
region of the main mixer where the radial vanes are located, the radial vanes having
inlet radii being within a range of from 0.010 inches to 0.030 inches;
further comprising one or more purge slots formed within the first ring, and one or more
splitters are provided, the splitters being disposed generally within the radial vanes.
37. The system of claim 36 further comprising a waveform formed and disposed upon the
splitters.
38. The system of claim 36, further comprising that in place of one or more of the radial
vanes, one or more conical vanes are formed generally upon the first ring and depending
radially inward therefrom.
39. The system of claim 38, further comprising a waveform formed and disposed upon the
splitters.
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MANISHA~SI~H-NAIR
Agent for the Applicant [IN/PA- 740]
LEX ORBIS
Intellectual Property Pnctice
709/710, Tolstoy House,
IS-17, Tolstoy Marg,
New Delhi-I 1000 I
2.-1