WO2016118129A1

WO2016118129A1 - Transition duct system

Info

Publication number: WO2016118129A1
Application number: PCT/US2015/012347
Authority: WO
Inventors: Matthew D. Montgomery; Alexander Ralph Beeck; Manish Kumar; David J. Wiebe
Original assignee: Siemens Energy, Inc.
Priority date: 2015-01-22
Filing date: 2015-01-22
Publication date: 2016-07-28

Abstract

A transition duct system (100) for routing a gas flow from a combustor (102) to the first stage (104) of a turbine section (106) in a combustion turbine engine (108), characterized in that the transition duct system (100) includes one or more irregularities positioned at or adjacent the converging flow joint (196), is disclosed. The transition duct system (100) may include a converging flow joint (196) formed by the intersection of a first side wall (172) of a first transition duct body (126) with a second side wall (194) of a second transition duct body (128). Furthermore, one or more irregularities may be positioned at or adjacent the converging flow joint (196). The one or more irregularities may increase the mixing of gas routed by the first transition duct body (126) and the second transition duct body (128), reducing the tendency for gas flow induced vibration of the turbine blade (142) and/or the penalty associated with unsteady turbine blade (142) loading, in particular embodiments.

Description

TRANSITION DUCT SYSTEM

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR

DEVELOPMENT

Development of this invention was supported in part by the United States Department of Energy, Advanced Turbine Development Program, Contract No. DE- FC26-05NT42644, Accordingly, the United States Government may have certain rights in this invention.

FIELD OF THE INVENTION

This invention is directed generally to gas turbine engines, and more particularly to a gas turbine engine having a transition duct system with irregularities.

BACKGROUND OF THE INVENTION

In conventional gas turbine engines, as shown in Figure 1, combustion gases created within a cofnbustor 10 are passed to a turbine assembly via a plurality of transition ducts 12. in many conventional systems, the transition ducts 12 extended longitudinally without any offset in a circumferential direction. A row of first stage vanes 14 were used to turn the combustion exhaust gases befor being passed to the row one turbine blades 16, The use of first stage vanes 14 in a turbine assembly to accelerate and turn the longitudinal combustor exhaust gas flow in the

circumferential direction presented several challenges. The vanes 14 a id the associated vane support structures were required to have high strength

characteristics to withstand the forces generated in changing the direction of extremely hot, high pressure gas flow over a substantial angle in a relativel short distance. The temperature of the gas flow and the heat generated by this turning process also require a vane cooling system. The forces and heat involved diminished materia! properties causing cracks to develop and otherwise damage the vanes and associated support structures. To accommodate these operating conditions and to provide a more robust design, as shown in Figures 2-7, the transition ducts 20 directing combustion gases from a combustor 22 to a turbine assembly 24 were skewed circumferential!y such that th outlets 26 of the transition ducts 20 were skewed circumferentiaily in the same direction of that the first row turbine vanes would otherwise skew the combustion exhaust gases in the circumferential direction. As such, row one turbine vanes were no longer needed becaus the exhaust gases emitted from the transition ducts 20 already included the correct circumferential vector, thereby eliminating the need for the row one turbine vanes. As shown in United States Patent Wo.

8,113,003, filing date August 12, 2006, issuance date February 14, 2012, which is incorporated herein in its entirety, the outlet of each transition duct is skewed in the circumferential direction relative to the inlet of each transition duct. While the transition duct system of the ⁽IS, Patent No, 8, 13,003 has eliminated th need for row one turbine vanes upstream of row one turbine blades Within a turbine assembly, there exists a need to improve the performance of such transition ducts,

SUMMARY OF THE INVENTION

A transition duct system for routing a gas flow from a combustor to the first stage of a turbine sectio in a co fousf on turbine engine, wherein the transition duct system includes one or more irregularities positioned a adjacent a converging flow joint, is disclosed, The transition duct system may include first and second transition duct bodies each having an internal passag extending between an inlet to an outlet and which each may expel gases into the first stage turbine with a tangential component A cohyer^ifig flow jbint may be temed by the intersection of a first side wall of the first transition duct body with a second side wal l of the second transition duct body, Furtherrnofe, one or more irregularities may be positioned at or adjacent the converging flow joint so that the converging flow joint is non-linear, The one or more irregularities may be one or more protrusions and/or one or mor scallops. The one or more irregularities may increase the mixing of gas routed by the first transition duct body and the second transition duet body. As such, in particular embodiments, the one or more irregularities may reduce the tendency for gas flow induced vibration of the turbine blade and/or the penalt associated with unsteady turbine blade loading.

For a better understanding of the invention, a coordinate system can be

the first stag blade array. The transition duct system includes a first transition duct body having an internal passage extending between an inlet and an outlet. The outlet of the first transition duct body is offset from the inlet in the longitudinal direction and the tangential direction. The outlet of the first transition duct body is formed from a radially outer side generally opposite to a radially inner side, and the radially outer and inner sides are coupled together with opposed first and second side walls. The transition duct system also includes a second transition duct body having an internal passage extending between an inlet and a outlet. The outlet of the second transition duct body is offset from the inlet in the longitudinal direction and the tangential direction. The outlet of the second transition duct body is formed from a radially outer side generall opposite to a radially inner side, and the radially outer and inner sides are coupled together ith opposed first and second side wails. Also* the first side wall of the first transition duct body intersects with the second side waii of the second transition duct body forming a converging flow joint, Furthermore, one or more irregularities are positioned at or adjacent the converging flow joint so that the converging flow joint is non-linear,

The one or more Irregularities may include a pluralit of irregularities. A first set of the pltira lit of ir reg liiar ftles rr¾ay be further positioned on the first side wail of the first transition duct body and a second set of the plurality of irregularities may be further positioned on the second side wall of the second transition duct body.

Additionally, a first set of the plurality of irregularities may be further positioned on the radially inner side of the first transition duct body and a second set of the plurality of irregularities may be furthe positioned on the radial iy outer side of the second transition duct body_*

At least one of the one or more irregularities may i nclude at least one protrusio having a length that extends f om the ositio at the converging flow joint to a positio longitudinally upstream from the converging flow joint. The at least one protrusion may have a heig ht that Increases ove a porti o of the length of the at least on© protrusion, Additionally , the at least one protrusion may be interrupted at one or more portions of the length of the at least one protrusion.

The position adjacent to the converging flow joint ma be a position longitudinall upstream from the converging flow joint. Furthermore, at least on of the one or more irregularities may be at least one protrusion having a length that extends from the positio longitudinally upstream from the converging; flow joint to a position further longitudinally upstream from the converging flo joint. The at least one protrusion may have a height that increases over a portion of the length of the at feast one protrusion. The at least one protrusion ma he interrupted at one or more portions of the length of the at least one protrusion.

At least one of the one or more irregu!anties may include at least one protrusion having a length that extends from the position at the converging flow joint to a position longitudinally upstream from the converging flow joint and located on at least one of the sides or walls of the first transition duet body. The length of the at least one protrusion may further extend from the position at the converging flow joint to a position longitudinally upstream from the converging flow joint and located on at least one of the sides Or wails of the second transition duGtjbOdy.

At least one of the one or more irregularities ma include at feast one scallop that provides curvature along an axis of the converging [ flow joint The curvature along the axis of the converging flow joint may include a curve in the first side wall of the first transition duct body that causes a first portion of the first side wall of the first transition duct body to extend in a di ection away m the axis of the converging flow joint. The curvature along the axis of the converging flow joint may also include a curve in the second s de wall of the second transition duct body that c uses a first portion of the second side w¾il of the second transition duct body to extend in a direction towards the axis of the converging flow joint. The curvature along the axis of the converging flow joint may include a second curve in the first side wall of the first transition duct body that causes a second portion of the first side wail of the first transition duct body to extend in a direction towards the axis of the converging flow joint The curvature along the ax include a second curve in the second sid^ wall of the second transition duct body that causes a second portion of the second side wall Of the second transition duct body to extend in a direction away from the axis of the converging flow joint.

A advantage of the transition duct system is that the one or more

irregularities positioned at or adjacent the converging flow joint may increase the mixing of gas routed by the first transition duct body and the second transition duct body. As such, the one or more Irregularities (such as one or more protrusions and/or one or more scallops) may reduce the tendency for gas flow induced vibration of the turbine blade and/or the penalty associated with unsteady turbine blade loading. These and other embodiments are described in more detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part of the specification, illustrate embodiments of the presently disclosed Invention and, together with the description, disclose the principies of the invention.

Figure 1 is a cross-sectioha! view of a portion of a gas turbine engine.

ducts at their downstream ends* which are coupled together.

Figure 1 is an internal view of a converging flow joint with irregularities.

Figure 15 is a cross-sectional view of the converging flow joint with irregularities taken along section line 15-15 in Figure 14. Figure 16 is a cross-sectional view of an irregularity taken along section line 16-16 in Figure 14.

Figure 7 is a cross-sectional yiew of another example of an irregularity taken along section line 16-16 in Figure 14.

Figure 18 is a cross-sectional view of irregularities taken along section line 18-

18 in Figure 14.

Figure 19 is a cross-sectional view of the converging flow joi nt with another example of irregularities taken along section line 15-15 in Figure 14. DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

As shown in Figures 849, a transition duct syste 00 for routing a gas flow from a combustor 102 to the first stage 104 of a turbine section 106 in a_.combustion turbine engine 08, wherein the transition duct system 100 includes one of more irregularities positioned at or adjacent a converging flow joint 196, is disclosed. The transition duct system 100 may include first and second transition duct bodies 126_¾ 128 each having an internal passage 130, 82 extending between an inlet 132, 184 to an outlet 134, 86 and which each may expel gases into the first stage iurbine 104 with a tangential component A converging fJcsvy 'joint 198 may be formed by the intersection of a first side wall 172 of the first tra sition duct body 126 with a second side wall 194 of the second transition duct body 128 , Furthermore, one or more irregularities may be ositioned at or adja nt th© converging flow joint 196 so that the converging flow joint 196 is nonlinear, The One or more irregularities may be one or more protrusions 200 and/or one o more scallops 204. The one or more irregularities ma inefe^

126 and the second transition duet body 128. As such, in particular embodiments, the one or more irregularities may fe^ flow induced vibration of the turbine blade 142 and/or the penalty associated with unsteady iurbine blade 142 loading.

As shown in Figs, 8-10, the transition duct system 100 ma route gas flow in a combustion turbine subsystem 138 that includes a first stage blade array 104 having a plurality of blades 142 extending in a radial direction from a rotor assembly 144 for rotation in a circumferential direction 146, whereby the circumferential direction 1 6 may have a tangential direction component 148. The combustion turbine subsystem 138 may also include an axis 150 of the rotor assembly 144 defining a longitudinal direction 152, and at least one combustor 102 located longitudinally upstream of the first stage blade array 04 and located radiall outboard of the first stage blade array 104.

The transition duct system 100 may include a plurality of transition duct bodies 126, 128 coupled together such that the duct bodies 126, 128 exhaust combustion gases in a downstream direction together with a tangential component 148, thereby eliminating the need for a first stage turbine van© row upstream from a first turbine blade row, as found i conventional gas turbine engines. In particular, as shown in Figure 13, the transition duct system 1 GO may include a first transition duct foody 126 having an internal passage 130 extending between an inlet 132 and an outlet 134, The outlet 134 of the first transition duct body 134 is offset from the inlet 132 in the longitudinal direction 152 and the tangential direction 148. The outlet 134 of the first transition duct body 126 may be formed from a radially outer side 68 generall opposite to a radially inner side 170, and the radially outer and inner sides 168, 170 may be coupled together with opposed first and second side walls 72, 174. The transition duct system 100 may include a seeonc I transition duct body 128 having an internal passage 182 extending between an inlet 184 and a outlet 186. The outlet 186 of the seco d ^ inlet 184 in the iongitudinai direction 52 and the tangential direction 148. The outlet 186 of the second transition duct body 128 may be formed fro

generally opposite to a radially Inner side 190, and the radially outer and inner sides 188, 90 may be coupled toother with opposed first: ar^ second sid

1S4,

Whe the first transition duct body 126 Is positioned next td the second transition ductbody 128, a first side wall 172 of the first transiiion duct body 126 intersects with a second side wall 194 of the second transition duct body 128 forming a converging flow joint 198 {show in Figures 11, 14 , and 15), In at least one embodiment, the first side wail 172 ofthe ' first transition duct body 126 may be configured to be cpplanar with second aide wail 194 of the second transiiion duct body 128 when asserribied beside the first transition duct bod 126. longitudinal axes 270, 272 (shown in Figure 13) of the first and second transition duct bodies 126, 128 may be offset t rn each other in the circumferential direction 146,

As is illustrated in Figures 14-15 and 19. one or more Irregularities may be positioned at or adjacent the converging flow joint 96. The irregularities may cause the converging flow joint 196 to be non-iinear, thereby increasing the mixing of the gas routed through transition duct bodies 6_» 128. For example, the irregularities may form vortices in the gas routed through transition duct bodies 126, 128, thereby Increasing the mixing of this gas. Furthermore, the irregularities may entrain flow and form shear instabilitie (and/or increase the strength of shear instabilities), which may roli-up to create more vortices. As such, in particular embodiments, the one or more Irregularities positioned at or adjacent the converging flow joint 198 may reduce tie tendency for gas flow Induced vibration of the turbine blade 142 andfor the penalty associated with unsteady turbine blade 2 loading,

The irregularities positioned at or adjacent the converging flow joint 196 may be any type of irregularities, For example, the Irregularities may be protrusions 200 (shown in Figures 14-18} formed (or otherwise positioned) so as to protrude into the gas flow routed through transition duct bodies 126, 8. As another example, the irregularities may be scallops 204 (shown in Figure 9) that proyiiie curvature along an axis 222 of the converging fibw joint 196. As a further ©xarnpie, the irregularities may be tabs, vortex generators, any other irregularity that may form vortices in the gas routed through transition duct bodies 126, 128, or any combination of the preceding examples.

Any number of irregularities may be positioned at o adjacent the converging flow joint 196, For example, only one irregularity may be positioned at or adjacent the converging flow joint 96. As another example, two or mo? e Irregularities may be positioned at or adjacent the converging flow joint 196. As further examples, three or more irregularities may be positioned at or adjacent the converging flow joint 196, four or more irregularities may be positioned at or adjacent the converging flow joint 196, six or more irregularities may fee positioned at or adjacent the converging flow joint 196, eight or more irregularities may foe positioned at or adjacent the converging flow joint 196, ten or more irregularities may be positioned at or adjacent the converging flow Joint 196, or any other number of irregularities may be positioned at or adjacent the converging flow joint 196.

The Irregularities may be positioned on any of the sides 170, 188 of the transition duct bodies 126, 28, on any of the wails 172, 94 of the transition duct bodies 26, 128, or on any combination of the sides 70, 188 and/or wails 1 2, 194 of the transition duct bodies 126, 128, For example, a set of irregularities (such as one or more irregularities} may be positioned on the first side wall 72 of the first transition duct body 126, a set of irregularities (such as one or more irregularities) may be positioned on the second side wall 1 4 of the second transition duct bod 128, a set of irregularities (such as one or more irregularities) ma be positioned on the radially inner side 170 of the first transition duct body 128, and/o a set of irregularities (such as one or more irregularities) may be positioned on the radiaiiy

side wall 194 of the second transition duct body 128. As such, the irregularity wraps around the converging flow joint 198.

As is discussed above, the irregularities may be positioned at or adjacent the con-verging flow joint 196. As is shown in Figure 18, the irregularity may be positioned adjacent the converging flow joint 196 when the irregularity {such as protrusion 200} Is positioned so that a gap 208 is provided between the irregularity and the converging flow joint 196. The gap 208 may be a gap 208 of any suitable distance, For example, the gap 208 may be 10 millimeters - 50 millimeters, As another example, the gap 208 ma be equal to 5% - 26% of the width of the converging flow joint 96. Furthermore, the gap 208 may extend from the converging flow joint 196 to a position longitudinally upstream of the convergi ng flow joint 196, as is seen in Figure 16. As such, the irregularity may have a length 210 that extends from a position iongitudinaily upstream of the converging flow joint 196 {e.g., position 201) to a position located further upstream of the converging flow joint 196 (e.g., position 203), On the other hand, the irregularities may be positioned at the converging flow joint 196 when there is no gap 208 between the irregularity and the converging flow joint 196. in such an example, the irregularity may extend all the way to the edge of the converging flow joint 196 (or may even wrap around the converging ow joint 196, as is discussed above). As such, the irregularity may have a length 210 that extends from the converging flow joint 196 fe.g., position 205) to a position located upstream of the converging flow joint 196 (e.g., position 203),

The irregularities may have any shape. For example, the irregularities (such as protrusions 200) may have a rectangle shape {as is show in Figure 14), a generally rectangle > shape, a squa e shapej a r generally square shape, a circular shape, a generally circular shape, an oval shape, a generally oval shape, a triangle shape, a generally triangular shape (as is shown in Figure 5), any other geometrical shape, or any combination of the preceding. Additionally, the shape of the irregularity may change over a length 210, width 218, and/or height 212 of the Irregularity, For example, as is shown in Figure 16, an irregularity (such as protrusion 200) may have a height 2 2 that ramps up (or increases In a y other way) along a portion of the length 210 of the irregularity. As another example, an irregularity (such as protrusion 200) may have a height 212 that ramps down (or decreases in any other way) along a portion of the length 210 of the irregularity. The increase and/or decrease in height 212 may occur over any amount of the length 21 D of the irregularity, such as one fourth, one third, one half, two thirds, three fourths, or any other amount of the length 210 of the irregularity.

As a further example, the length 210 of the irregularity (such as a protrusion 200) may include one or more interruptions 216, as Is shown in Figure 17, An interruption 218 may decrease {or increase) the height 212 of the irregularity along the length of the interruptio 2 6, The interruption may decreas (or increase) the height by any amount, such as one fourth, one third, one half, two thirds, three fourths, the full height 212, or any other amount of height 212. Furthermore, each Interruption 216 may have a length thai extends over any portion of the length 210 of the irregularity, such as one tenth, one eighth, one fifth, one fourth, one half, or any other portion of the lengt 210 of the irregularity. The irregularit may include any number of interruptions 2 6 along its length 210, such as one interruption 216, two Interruptions 216, three interruptions 216, four interruptions 216, or five or more interruptions 216.

The irregularities may have any length 2 0, height 212, and/or width 218. In particular embodiments, the length 2 0, height 212, and/or idth 218 may be based on each other. For example, the height 212 of an irregularity may be 2 to 4 times the width 218 of the irregularity. As another example, the height 212 of an irregularity may be 1 to 4 times the width 218 of the irregularity. Ih such an example, th height 212 may he equal (or generally eq¾

Furthermore, the irregularities may have any amount of spacing 220 between adjacent irregularities. For example, the spacing 220 between adjacent irregularities ma be 3 to 6 times the width 218 of the Irregularity. Additionally, the length 210, height 212, width 218, and/or spacing 220 may he different (or otherwise vary) for one or more of the irreg ularities positioned at or adjacent the converging flow joint 196.

As is discussed above, the irregularities may further be one o more scallops 204 (as is illustrated in Figure 19). A scallop 204 may provide curvature along the axis 222 of the converging flow joint. For example, a scallop 204 may provide a curve in the first side wall 17 of the first transition duct bod 126 that causes a first portion 224 of the first side wall 172 of the first transition duct body 126^' to. extend in a d irection away from the axis 222 of the converging flow joint 196, and may further provide a curve in the second side waii 194 of the second transition duct body 128 that causes a first portion 226 of the second side wall 194 of the second transition duct bod 128 to extend in a direction towards the axis 222 of the converging flow joint 196, As such, in particular embodiments, the curves in the first side wail 172 of the first transition duct body 126 and the second side wall 194 of the second transition duct body 126 may form a convex curve that protrudes into the gas routed by the first transition duct body 126 and may also form a concave curve that provides an indention in the second transition duct bod 128. As another example, a scallop 20 may provide a curve in the first side wall 172 of the first transition duct body 126 that causes a second portio 228 of the first side wail 172 of the first transition duct body 1 6 to extend in a direction toward the axis 22 of the converging flow joint 196, and may further provide a curve in the second side waii 194 of the second transition duct body 1 8 that causes a second portion 230 of the second side wail 194 of the second transition duct body 128 to extend in a direction awa from the axis 222 of the converging flow joint 96. As such, in particular embodiments, the curves in the first side wall 172 of the first transition duct body 6 and the second side wall 194 of the second transition duct body 126 may form a concave curve that provides an indention in the first transition duet body 1 6 and may also form a convex curve that protrudes info the gas routed by the second transition duct body 128.

Any number of scallops 204 may be positioned at or adjacent the converging flow joint 196, as is discussed a o e with regard to irrep!anttes. Furthermore, the scallops 20 may foe positioned on any of the sides 1 0, 88 of the transition duct bodies 126, 28_» on any of the walls 172, 94 of the transition duct bodies 128, 28, or on any combi nation of the sides 70, 188 and/or wails 2, 194 of the transiti on duet bodies 26, 128, as is also discussed above with regard to irregularities. The curves provided by the scallop 204 may have any shape and/Or size, as is discussed above with regard to irreguiarities. Additionally, the scallops 204 ma be formed in an manner. Although Figures 15 and 19 illustrate the irregularities as being either protrusions 200 or scallops 204, irregularities may be any combination of one or more protrusions 200, one or more scallops 204, or one or more other irregularities. Furthermore, although Figures 15 and 19 illustrate all of the irregularities as being positioned either at or adjacent the converging flow joint 96, on© or more irregularities may positioned at the converging flow joint 196 while one or more other irregularities are positioned adjacent the converging flow joint 196. Additionally, one or more of the irregularities may include (or be connected to) a cooling system that may cool the irregularity. For example, cooling air may flow inside the radially outer sides 188, 188, the radially inner sides 70, 90, the first side walis 172, 192, and/or the second side walls 174, 194. This cooling air may further flow through the irregularities (such as protrusions 200 and/or scallops 204), providing cooling to the irregularities before exiting through one or more holes in the irregularities into the gas routed through transition duct bodies 128, 128.

The foregoing is provided for purposes of illustrating, explaining, and describing embodiments of this invention, lylodifications and adaptations to these embodiments will be apparent to those skilled in the a t and may be made without departing from the scope or spirit of this invention.

Claims

CLAIMS We claim:

1. A transition duct system (100) for routing gas flow in a combustion turbine subsystem (138) that includes a first stage (104) blade array having a plurality of blades (142) ©Mending in a radial direction from a rotor assembly ( 44) for rotation in a circumferential direction (1 6), the circumferential direction (146) having a tangential direction (148) component, an axis ( 50) of the rotor assembly (144) defining a longitudinal direction ( 52), and at least one combustof (102) located longitudinally upstream of the first stage (104) blade array and located radialty outboard of the first stag (104) blade array, the transition duct system (100) characterized in thai:

a first transition duct body (126) having an infernal passage ( 30) extending between an inlet (132) and an outlet (134);

characterized in that the outlet (134) of the first transition duet body (126) is offset from the inlet (132) in the longitudinal direction (152) and the tangential direction (148);

characterized in that the outlet ( 34) of the first transition duct body (128) is formed from a radially outer side ( 68) generally opposite to a radially inner Side (170), and the radially outer and inner sides (168, 170) are coupled together with opposed first and second side ¾Ji¾ (172, 74);

a second transition duct body (128) having an Internal passage (182) extending between an inlet 184) and ah

characterized in that the outlet ( 86) of the second transition duct body (128) is offset from the inlet ( 84) in the longitudinal direction (152) and the tangential direction (148);

characterized i n that the outlet (186) of the second transition duct body (128) is formed from a radially outer side (188) generall opposite to a radially inner sid (1©0), and the radially outer and inner sides (188, 90) are coupled together with opposed first and second side walls (192, 194); characterized in that the first side Wail (172) of the first transition duct body (128) intersects with the second side wall (194) of the second transition duct body (128) forming a converging flow joint (196); and

characterized in that one or more irreguiarities ar positioned at or adjacent the converging flow joint (196) so that the converging flow joint (198) is non-linear.

2. The transition duct system (100) of claim 1 , characterized in that the one or more irregularities comprises a plurality of Irregularities.

3. The transition duct system ( 00) of claim 2, characterized in that a first set of the plurality of irregularities are further positioned on the first side wall (172) of the first transition duct body (126) and a second set of the plurality of irregularities are further positioned on the second side wall ( 84) of the second transition duet body (128),

4. The transition duct system (100) of claim 2, characterized in that a first set of the plurality of irregularities are further positioned on the radially inner side (170) of the first transition duct body (126) and a second set of the plurality of irregularities are further positioned on the radially outer side (188) of the second transition duct body ( 28).

5. The transition duct system (100) of claim 1 , characterized in that at least one of the one or more irregularities comprises at least one protrusion (200) having a length (2 0) that extends from th posiion at the converging flow joint (196) to a position longitudinally upstream from the converging flow joint (196).

6. The transition duct system ( 00) of claim 5, characterized in that the at least one protrusion (200) has a height (212) that increases over a portion of the length (210) of the at least one protrusion (200) .

7. The transition duct system (100} of claim 5, characterized in that the at (east one protrusion (200) is interrupted at one or more portions of the length (210) of the at least one protrusion (200).

8. The transition duct system ( 00) of claim 1 , characterized in that the position adjacent to the converging flow joint (196) is a position longitudinally upstream from the converging flow joint (196) and characterized in that at least one of the one or more irregularities comprises at least one protrusion (200) having a length (210) that extends from the position longitudinall upstream from the converging flow joint (196) to a position further longitudinally upstream from the converging flow joint ( 96).

9. The transition duct system (100) of claim 8, characterized in that the at least one protrusion (200) has a height (212) that increases over a portion of the length (210) of the at least one protrusion (200),

10. The transitio duct system (100) of claim 8, charaeterizeCi in that the at !east one protrusion (200) is interrupted at one or more portions of the length (210) of the at least one protrusion (200).

(128),

12. The transition duct system (100) of claim 1 , characterized in that at least one of the one or more i rregularities comprises at least one scallop (204) that provides curvature along an axis (222) of the converging flow joint (196).

13. The transiiion duct system (100) of claim 12, characterized in that the curvature along the axis (222) of the converging flow joint (196) comprises a curve in the first side wait (172) of the first transition duct body (128) that causes a first portion of the first side wail (172) of the first transition duct body (126) to extend in a direction away from the axis (222) of the converging {low Joint (196) , and characterized in that the curvature aiong the axis (222) of the converging flow joint (196) comprises a curve in the second side wall (194) of the second transition duct bod (128) that causes a first portion of the second side wall (194) of the second transition duct body ( 28) to extend in a direction towards the axis (222) of the converging flow joint ( 96).

14. The transition duct system (100) of c!aim 13, characterized in that the curvature along the axis (222) Of the converging flow joint (186) comprises a second curve in the first side wall (172) of the first transition duct Body (126) that causes a second portion of the first side wall (1 2) Of the first transition duct body (126) to extend in a direction towards the axis (222) of the oohyerging flow joint ( 96), and characterized in that the curvature along the axis (222) of the converging flow joi nt (196) comprises a second curve in the second side vvali (194) of the second transition duet body (128) that causes a second portion of the second side wali (194) of the second transition duct body (128) to extend in a direction away from axis (222) of the converging flow joint (196).