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 transition ducts for routing gas flow from combustors to the turbine section of gas turbine engines.

BACKGROUND OF THE INVENTION

In conventional gas turbine engines, as shown in Figure 1 , combustion gases created within a combustor 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 before 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 and 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 relatively 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 material 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 2-10, the transition ducts 20 directing combustion gases from a combustor 22 to a turbine assembly 24 were skewed circumferentially such that the outlets 26 of the transition ducts 20 were skewed circumferentially 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 because 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 8,1 13,003, filing date August 12, 2008, 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 US Patent No. 8,1 13,003 has eliminated the need for row one turbine vanes upstream of row one turbine blades within a turbine assembly, there exists a need to increase the useful life of the skewed transition duct system by eliminating areas of high stress, which are shown in Figures 6-10.

SUMMARY OF THE INVENTION

A transition duct system for routing a gas flow from a combustor to the first stage of a turbine section in a combustion turbine engine, wherein the transition duct system includes one or more converging flow joint inserts forming a trailing edge at an intersection between adjacent transition duct is disclosed. The transition duct system may include a transition duct having an internal passage extending between an inlet to an outlet and may expel gases into the first stage turbine with a tangential component. The converging flow joint insert may be contained within a converging flow joint insert receiver and disconnected from the transition duct bodies by which the converging flow joint insert is positioned. Being disconnected eliminates stress formation within the converging flow joint insert, thereby enhancing the life of the insert. The converging flow joint insert may be removable such that the insert can be replaced once worn beyond design limits.

For a better understanding of the invention, a coordinate system can be applied to such a turbine system to assist in the description of the relative location of components in the system and movement within the system. The axis of rotation of the rotor assembly extends longitudinally through the compressor section, the combustion section and the turbine section and defines a longitudinal direction.

Viewed from the perspective of the general operational flow pattern through the various sections, the turbine components can be described as being located longitudinally upstream or downstream relative to each other. For example, the compressor section is longitudinally upstream of the combustion section and the turbine section is longitudinally downstream of the combustion section.

The location of the various components away from the central rotor axis or other longitudinal axis can be described in a radial direction. Thus, for example, the blade extends in a radial direction, or radially, from the rotor disc. Locations further away from a longitudinal axis, such as the central rotor axis, can be described as radially outward or outboard compared to closer locations that are radially inward or inboard.

The third coordinate direction— a circumferential direction-can describe the location of a particular component with reference to an imaginary circle around a longitudinal axis, such as the central axis of the rotor assembly. For example, looking longitudinally downstream at an array of turbine blades in a turbine engine, one would see each of the blades extending radially outwardly in several radial directions. Thus, the radial direction can describe the size of the reference circle and the circumferential direction can describe the angular location on the reference circle.

In at least one embodiment, the transition duct system routes gas flow in a combustion turbine subsystem that includes a first stage blade array having a plurality of blades extending in a radial direction from a rotor assembly for rotation in a circumferential direction, whereby the circumferential direction may have a tangential direction component. The combustion turbine subsystem may have an axis of the rotor assembly defining a longitudinal direction and at least one

combustor located longitudinally upstream of the first stage blade array and located radially outboard of the first stage blade array. The transition duct system may include a first transition duct body having an internal passage extending between an inlet and an outlet. The outlet of the first transition duct body may be offset from the inlet in the longitudinal direction and the tangential direction. The outlet of the first transition duct body may be formed from a radially outer side generally opposite to a radially inner side, and the radially outer and inner sides may be coupled together with opposed first and second side walls. The transition duct system may also include a second transition duct body having an internal passage extending between an inlet and an outlet. The outlet of the second transition duct body may be offset from the inlet in the longitudinal direction and the tangential direction. The outlet of the second transition duct body may be formed from a radially outer side generally opposite to a radially inner side, and the radially outer and inner sides may be coupled together with opposed first and second side walls. A first side of the first transition duct body may intersect with a second side of the second transition duct body forming a converging flow joint. The transition duct system may include a converging flow joint insert extending through an outer wall and positioned at a downstream end of the converging flow joint to form a trailing edge of the converging flow joint.

The converging flow joint insert may be formed from a body with a flange positioned at a first end of the insert to prevent the converging flow joint insert from being ingested into a turbine downstream of the transition duct system. The flange of the converging flow joint insert may have a larger cross-sectional area than the body of the converging flow joint insert. The body of the converging flow joint insert may include a first section with a uniform thickness from a first side to a second side opposite to the first side and a second section extending from the first section and forming an outer downstream tip of the converging flow joint insert. The second section may have a nonuniform thickness with a thickness at the outer downstream tip being less than a thickness at an upstream edge of the second section. The converging flow joint insert may be formed from a first side that forms an extension of the first side of the first transition duct body and a second side that forms an extension of the second side of the second transition duct body.

The transition duct system may include an internal cooling system within the converging flow joint insert. The internal cooling system may include one or more internal cooling chambers in fluid communication with one or more exhaust orifices extending from an inlet in the internal cooling chamber through an outer wall forming a second section of the converging flow joint insert. The second section may include an outer downstream tip of the converging flow joint insert, and an outlet of the exhaust orifice may be positioned at an outer surface of the at least one internal cooling chamber, in at least one embodiment, the at least one exhaust orifice may be a plurality of exhaust orifices extending from inlets in the internal cooling chamber through the outer wall forming the second section of the converging flow joint insert to outlets of the exhaust orifice positioned at the outer surface of the internal cooling chamber. The internal cooling system may include one or more impingement plates positioned in the internal cooling chamber and extending from a first side to a second side opposite to the first side forming the converging flow joint insert. The

impingement plate may include one or a plurality of impingement orifices. The internal cooling system may include one or more internal cooling chambers having an internal volume less than one half of a volume of outer walls forming the converging flow joint insert.

The transition duct system may include one or more exhaust orifices extending from an inlet in the internal cooling chamber through an outer wall forming a first section of the converging flow joint insert. The first section may have a uniform thickness from a first side to a second side opposite to the first side. The transition duct system may include one or more exhaust orifices extending from an inlet in the internal cooling chamber through an outer wall forming a second section of the converging flow joint insert. The second section may extend from the first section and may form an outer downstream tip of the converging flow joint insert. The second section may have a nonuniform thickness with a thickness at the outer downstream tip being less than a thickness at an upstream edge of the second section.

The converging flow joint insert may be disconnected from the first side of the first transition duct body and the second side of the of the second transition duct body, which eliminates mechanical stress within the converging flow joint insert. The converging flow joint insert may be removably attached within the transition duct system. The transition duct system may include a converging flow joint insert receiver positioned at the converging flow joint and configured to receive the converging flow joint insert. The converging flow joint insert receiver may include one or more inner walls defining one or more insert receiving orifices. The converging flow joint insert receiver may provide support to the converging flow joint insert and may include at least one flange contact surface configured to support a flange positioned at a first end of the insert to prevent the converging flow joint insert from being ingested into a turbine downstream of the transition duct system.

In at least one embodiment, a first side wall of the first transition duct body may be configured to be coplanar with a second side wall of the second transition duct body when assembled beside the first transition duct body. Longitudinal axes of the first and second transition duct bodies may be offset from each other in the circumferential direction.

An advantage of the transition duct system is that the converging flow joint insert replaces an area of high mechanical stress within transition duct systems with a converging flow joint insert that resides within a converging flow joint insert receiver and is exposed to minimal and possibly no mechanical stress.

Another advantage of the transition duct system is that the converging flow joint insert removes the sharp narrow geometry and the resulting stress

concentrations from the converging flow joint between adjacent transition ducts and incorporates the sharp narrow geometry into the converging flow joint insert.

Yet another advantage of the transition duct system is that the converging flow joint insert is removably and replaceable, thereby enabling the converging flow joint insert to be replaced when worn due to erosion from high velocity gases.

Another advantage of the transition duct system is that the converging flow joint insert is supported by a converging flow joint insert receiver that is formed from a buildup of material at the intersection of sidewalls proximate to outlets of adjacent transition ducts that increase the strength of the walls so they can better resist the pressure loading and distributing the stresses over a larger area, thereby reducing the stress levels and increasing the design life of the transition duct system.

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 principles of the invention. Figure 1 is a cross-sectional view of a portion of a gas turbine engine.

Figure 2 is an downstream facing perspective view of an upper half of a plurality of can-annular combustors coupled to transition ducts.

Figure 3 is an upstream longitudinal view of a circular array of transition ducts. Figure 4 is a side view of a transition duct relative to row one turbine blades.

Figure 5 is a top view of a circular array of transition ducts.

Figure 6 is a top view of a fitting in which two adjacent transition ducts are positioned.

Figure 7 is a cross-sectional view of the two adjacent transition ducts of Figure 6 taken along section line 7-7 in Figure 6 in which an area of high mechanical stress is identified.

Figure 8 is a perspective detailed view of the area of high mechanical stress at the intersection between the adjacent transition ducts taken along detail line 8-8 in Figure 7.

Figure 9 is another perspective view of the area of high mechanical stress at the intersection between the adjacent transition ducts taken along detail line 8-8 shown in Figure 7.

Figure 10 is a partial perspective view of two transition ducts looking upstream into the internal passageways of the transition ducts showing how the adjacent transition ducts next together at the exhaust outlets.

Figure 1 1 is an downstream facing perspective view of an upper half of a plurality of can-annular combustors coupled to transition ducts.

Figure 12 is an upstream longitudinal view of a circular array of transition ducts.

Figure 13 is a side view of a transition duct relative to row one turbine blades.

Figure 14 is a perspective view of a plurality of transition ducts coupled together immediately upstream of row one turbine blades.

Figure 15 is a simplified side view of a transition duct shown in Figure 10. Figure 16 is a perspective view of external surfaces of two adjacent transition ducts at their downstream ends, which are coupled together and including a converging flow joint insert positioned within a converging flow joint insert receiver at an intersection between two adjacent transition ducts. Figure 17 is a perspective view of the converging flow joint insert positioned within a converging flow joint insert receiver at an intersection between two adjacent transition ducts.

Figure 18 is a cross-sectional view of the converging flow joint between two adjacent transition ducts taken at section line 18-18 in Figure 16.

Figure 19 is a cross-sectional view of the converging flow joint between two adjacent transition ducts taken at section line 19-19 in Figure 16.

Figure 20 is a cross-sectional view of the converging flow joint between two adjacent transition ducts taken at section line 20-20 in Figure 16.

Figure 21 is a cross-sectional view of the converging flow joint between two adjacent transition ducts taken at section line 21 -21 in Figure 16.

Figure 22 is a perspective view of internal surfaces of a converging flow joint insert receiver at a converging flow joint between two adjacent transition ducts at their downstream ends, whereby the converging flow joint insert is not contained within the converging flow joint insert receiver.

Figure 23 is a perspective view of internal surfaces of a converging flow joint insert receiver at a converging flow joint between two adjacent transition ducts at their downstream ends with the converging flow joint insert positioned within the converging flow joint insert receiver.

Figure 24 is perspective view a converging flow joint insert at a different angle than in Figure 23.

Figure 25 is a perspective view of external surfaces of a converging flow joint insert receiver at a converging flow joint between two adjacent transition ducts at their downstream ends, whereby the converging flow joint insert is not contained within the converging flow joint insert receiver and a downstream internal surface of the converging flow joint insert receiver is displayed.

Figure 26 is another perspective view of external surfaces of a converging flow joint insert receiver, taken from a different perspective than Figure 25, at a converging flow joint between two adjacent transition ducts at their downstream ends, whereby the converging flow joint insert is not contained within the converging flow joint insert receiver and an upstream internal surface of the converging flow joint insert receiver is displayed. Figure 27 is a perspective view of external surfaces of a non-insert side of the converging flow joint insert receiver at a converging flow joint between two adjacent transition ducts at their downstream ends.

Figure 28 is a cross-sectional, top view of the converging flow joint insert taken along section lines 28-28 in Figure 23, as shown relative to a perspective view of external surfaces of two adjacent transition ducts at their downstream ends, which are coupled together and including a converging flow joint insert positioned within a converging flow joint insert receiver at an intersection between two adjacent transition ducts.

Figure 29 is a cross-sectional side view of the converging flow joint insert taken along section line 29-29 in Figure 28.

Figure 30 is a bottom view of the converging flow joint insert shown in Figure

29.

Figure 31 is a front view of the converging flow joint insert shown in Figure 29. Figure 32 is a cross-sectional view of the converging flow joint insert positioned within a converging flow joint insert receiver at an intersection between two adjacent transition ducts taken along section line 32-32 in Figure 28.

Figure 33 is a cross-sectional side view of the converging flow joint insert with an internal cooling system together with alternative outer surface locations showing possible alternative positions of the outer surface in other embodiments.

Figure 34 is an upstream end view of the converging flow joint insert of Figure

33.

Figure 35 is a cross-sectional view of the converging flow joint insert taken at section line 35-35 in Figure 33.

Figure 36 is a cross-sectional view of another embodiment of the converging flow joint insert with a different internal cooling system configuration taken at section line 35-35 in Figure 33.

Figure 37 is a cross-sectional view of the converging flow joint insert configuration taken at section line 37-37 in Figure 16.

Figure 38 is a perspective view of an alternative embodiment of internal surfaces of a converging flow joint insert receiver at a converging flow joint between two adjacent transition ducts at their downstream ends with an alternative embodiment of the converging flow joint insert positioned within a recess where the converging flow joint insert does not protrude through the outer wall defining the recess.

Figure 39 is a side view of the converging flow joint insert of Figure 38.

Figure 40 is a right side view of the converging flow joint insert of Figure 38.

Figure 41 is a left side view of the converging flow joint insert of Figure 38. Figure 42 is a perspective view of the converging flow joint insert of Figure 38. Figure 43 is a cross-sectional side view of the converging flow joint insert of Figure 38 taken along section line 43-43 in Figure 42.

Figure 44 is a perspective view of a first end of the pin extending through the converging flow joint insert of Figure 38.

Figure 45 is a perspective view of a second end of the pin extending through the converging flow joint insert of Figure 38.

Figure 46 is a cross-sectional view of the converging flow joint insert of Figure 38 positioned within a converging flow joint insert receiver at an intersection between two adjacent transition ducts.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

As shown in Figures 1 1 -46, 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, wherein the transition duct system 100 includes one or more converging flow joint inserts 120 forming a trailing edge 122 at an intersection 124 between adjacent transition duct 126, 128 is disclosed. The transition duct system 100 may include a transition duct 126 having an internal passage 130 extending between an inlet 132 to an outlet 134 and may expel gases into the first stage turbine 1 14 with a tangential component. The converging flow joint insert 120 may be contained within a converging flow joint insert receiver 136 and disconnected from the transition duct bodies 126, 128 by which the converging flow joint insert 120 is positioned. Being disconnected on side surfaces eliminates stress formation within the converging flow joint insert 120, thereby enhancing the life of the insert

120. The converging flow joint insert 120 may be removable such that the insert 120 can be replaced once worn beyond design limits. In at least one embodiment, the transition duct system 100 may 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 146 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 104 and located radially outboard of the first stage blade array 104.

The transition duct system 100 may include a plurality of transition ducts 126,

128 coupled together such that the ducts 126, 128 exhaust combustion gases in a downstream direction together with a tangential component 148, thereby eliminating the need for a first stage turbine vane row upstream from a first turbine blade row, as found in convention gas turbine engines. In particular, the transition duct system 100 may include a first transition duct body 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 168 generally 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 172, 174.

The transition duct system 100 may include a second transition duct body 128 having an internal passage 182 extending between an inlet 184 and an outlet 186. The outlet 186 of the second transition duct body 128 may be offset from the inlet 184 in the longitudinal direction 152 and the tangential direction 148. The outlet 186 of the second transition duct body 128 may be formed from a radially outer side 188 generally opposite to a radially inner side 190, and the radially outer and inner sides 188, 190 may be coupled together with opposed first and second side walls 192, 194. When the first transition duct 126 is positioned next to the second transition duct body 128, a first side wall 172 of the first transition duct body 126 intersects with a second side wall 194 of the second transition duct body 128 forming a converging flow joint 196. In at least one embodiment, the first side wall 172 of the first transition duct body 126 may be configured to be coplanar with a second side wall 194 of the second transition duct body 128 when assembled beside the first transition duct body 126. Longitudinal axes 270, 272 of the first and second transition duct bodies 126, 128 may be offset from each other in the circumferential direction 146.

The transition duct system 100 may also include a converging flow joint insert 120 extending through an outer wall 202 and positioned at a downstream end 204 of the converging flow joint 196 to form the trailing edge 122 of the converging flow joint 196. The converging flow joint insert 120 is positioned in a location of high mechanical stress in conventional systems. The converging flow joint insert 120 may be disconnected from the first side 172 of the first transition duct body 126 and the second side 194 of the of the second transition duct body 128. Being

disconnected, yet positioned to act as the trailing edge 122 of the converging flow joint 196 enables the converging flow joint insert 120 to function without being subjected to mechanical stress. The converging flow joint insert 120 may be contained within a converging flow joint insert receiver 136. The converging flow joint insert receiver 136 may be positioned at the converging flow joint 196 and configured to receive the converging flow joint insert 120. The converging flow joint insert receiver 136 may include one or more inner walls 208 defining at least one insert receiving orifice 210 that provides support to the converging flow joint insert 120, as shown in Figures 22-26. The converging flow joint insert receiver 136 may also include one or more flange contact surfaces 212 configured to support a flange 214, as shown in Figures 29-37, positioned at a first end 216 of the insert 120 to prevent the converging flow joint insert 120 from being ingested into a turbine downstream of the transition duct system 100. The converging flow joint insert 120 may be removably attached within the transition duct system 100. The converging flow joint insert 120 may be coupled to the converging flow joint insert receiver 136 via a weld or appropriate method already invented or yet to be invented.

The converging flow joint insert 120 may be formed from a body 218 with a flange 214 positioned at the first end 216 of the insert 120 to prevent the converging flow joint insert 120 from being ingested into a turbine downstream of the transition duct system 100. The flange 214 of the converging flow joint insert 120 may have a larger cross-sectional area than the body 218 of the converging flow joint insert 120. The converging flow joint insert 120 may be formed from a first side 260 that forms an extension of the first side wall 172 of the first transition duct body 126 and a second side 262 that forms an extension of the second side wall 194 of the second transition duct body 128. The flange 214 and the body 218 may be a unitary structure. In another embodiment, the flange 214 may be coupled to the body 218 via welding, brazing or other appropriate connection mechanism.

The body 218 of the converging flow joint insert 120 may include a first section 220 with a uniform thickness from a first side 222 to a second side 224 opposite to the first side 222 and a second section 226 extending from the first section 220 and forming an outer downstream tip 228 of the converging flow joint insert 120. The second section 226 has a nonuniform thickness with a thickness at the outer downstream tip 228 being less than a thickness at an upstream edge 230. As shown in Figure 20, the first section 220 of the converging flow joint insert 120 may be positioned closer to the converging flow joint insert receiver 136 than the second section 226. The second section 226 may include a first side 231 and a second side 233 that is on an opposite side from the first side 231 . The first and second sides 231 , 233 may have a somewhat convex surface that each replicate the inner surfaces of the first side wall 172 of the first transition duct body 126 and the second side wall 194 of the second transition duct body 128. The trailing edge 229 of the converging flow joint insert 120 may have a generally curved shape extending from the first section 220 towards a distal end 232 of the second section 226 to follow the contour of the intersection 124 between the first and second transition bodies 126, 128.

The converging flow joint insert 120 may include an internal cooling system

234 within the converging flow joint insert 120, as shown in Figures 33-36. The internal cooling system 234 may have any appropriate shape configured to

adequately cool the converging flow joint insert 120 when extending into the hot gas path at the intersection 124 of the first and second transition ducts 126, 128. The internal cooling system 234 may include one or more internal cooling chambers 236 in fluid communication with one or more exhaust orifices 238 extending from an inlet 240 in the internal cooling chamber 236 through an outer wall 242 forming the second section 226 of the converging flow joint insert 120. The second section 226 may include an outer downstream tip 228 of the converging flow joint insert 120, and an outlet 244 of the at least one exhaust orifice 238 may be positioned at an outer surface 246 of the internal cooling chamber 236. In at least one embodiment, the internal cooling system 234 may include a plurality of exhaust orifices 238 extending from inlets 240 in the internal cooling chamber 236 through the outer wall 242 forming the second section 226 of the converging flow joint insert 120 to outlets 244 of the exhaust orifice 238 positioned at the outer surface 246 of the internal cooling chamber 236.

The internal cooling system 234 may include one or more impingement plates

248, as shown in Figure 35, positioned in the internal cooling chamber 236 and extending from a first side 250 to a second side 252 opposite to the first side 250 forming the converging flow joint insert 120. The impingement plate 120 may include one or more impingement orifices 254, and, in at least one embodiment, may include a plurality of impingement orifices 254. In another embodiment,, as shown in Figure 36, the internal cooling system 234 may include one or more internal cooling chambers 236 having an internal volume less than one half of a volume of outer walls 242 forming the converging flow joint insert 120. One or more exhaust orifices 238 may extend from an inlet 240 in the internal cooling chamber 236 through the outer wall 256 forming the first section 220 of the converging flow joint insert 120. The first section 220 may have a uniform thickness from the first side 222 to the second side 224 opposite to the first side 222. One or more exhaust orifices 238 may extend from an inlet 240 in the internal cooling chamber 236 through an outer wall 242 forming a second section 226 of the converging flow joint insert 120. The second section 226 may extend from the first section 220 and may form an outer downstream tip 228 of the converging flow joint insert 120. The second section 226 may have a nonuniform thickness with a thickness at the outer downstream tip 228 being less than a thickness at an upstream edge 230 of the second section 226.

In another embodiment, as shown in Figures 38-46, the transition duct system 100 may have an alternative configuration. The transition duct system 100 may include the first and second transition duct bodies 126, 128 as previously set forth, but may include an alternative configuration for the converging flow join insert 120. The transition duct system 100 may include converging flow joint insert 120 positioned within a recess 300 at a downstream end 302 of the converging flow joint 196 to form a trailing edge 301 of the converging flow joint 196. The recess 300 may be positioned within the converging flow joint 196 and may be configured to receive and house the converging flow joint insert 120. In this embodiment, the converging flow join insert 120 may extend through the outer wall 202 at a downstream end 204 of the converging flow joint 196. Instead, the converging flow join insert 120 may be contained completely within the recess 300 with a portion exposed to form the trailing edge 122 of the converging flow joint 196.

The transition duct system 100 may be held in place within the recess 300 via an insert attachment system 303 configured to attached the converging flow joint insert 120 to the converging flow joint 196. In at least one embodiment, the insert attachment system 303 may be formed from one or more pins 304 extending into the converging flow joint insert 120 and into the converging flow joint 196. In at least one embodiment, the insert attachment system 303 may include one or more pins 304 extending through the converging flow joint insert 120 and through the converging flow joint 196. The insert attachment system 303 may include one or more collars 306 for securing a first end 308 of the pin 304. The collar 306 may be integrally formed with the pin 304 or may be attached to the pin via welding or other appropriate method. A second end 310 of the pin 304 that is generally on an opposite end of the pin 304 relative to the first end 308 may or may not include a collar 306. The pin 304 near the second end 310 may be secured to the converging flow joint 196 via welding or other appropriate method.

The transition duct system 100 may include an internal cooling system 312 within the converging flow joint insert 120. The internal cooling system 312 may include one or more internal cooling chambers 314 in fluid communication with one or more exhaust orifices 316 extending from an inlet 318 in the internal cooling chamber 314 through an outer wall 320 forming the converging flow joint insert 120. The exhaust orifice 316 of the internal cooling system 312 may include one or more exhaust orifices 316 extending from the internal cooling chamber 314 to an exhaust outlet 322 at an outer surface 324 facing a surface 326 forming the recess 300 in which the converging flow joint insert 120 resides. The internal cooling system 312 may also include one or more exhaust orifices 318 extending from the internal cooling chamber 314 to exhaust outlets 330 at an outer surface 332 facing

downstream and away from the recess 300 in which the converging flow joint insert 120 resides.

In at least one embodiment, a portion of the internal cooling system 312 may be contained within the pin 304 forming at least a portion of the insert attachment system 303 configured to attached the converging flow joint insert 120 to the converging flow joint 196. The pin 304 may include an inner channel 334 having at least one inlet 336 positioned outside of the recess 300 at the downstream end 204 of the converging flow joint 196 and may include one or more exhaust outlets 338 in fluid communication with an internal cooling chamber 340. In at least one

embodiment, the pin 304 may include a first inlet 342 at a first end 344 of the pin 304 in communication with the inner channel 334 in the pin 304 and may include a second inlet 346 in a second end 348 of the pin 304 at an opposite end of the pin 304 from the first end 344. The converging flow joint insert 120 may include a body 350 including an outer section 352, an inner section 354 and a middle section 356 between the outer and inner sections 352, 354. The middle section 356 may have a cross-sectional area narrower in width than cross-sectional areas of the outer and inner sections 352, 354. The inner section 354 may extend further downstream than the middle section 356, and the outer section 352 may extend further downstream than the inner section 354. A cross-sectional area at a distal end 358 of the outer section 352 may be larger than a cross-sectional area at a distal end 360 of the inner section 354, as shown in Figure 43.

In at least one embodiment, the converging flow joint insert 120 of the converging flow joint 196 may be essentially load free when positioned within the converging flow joint insert receiver 136. In another embodiment, the converging flow joint insert 120 of the converging flow joint 196 may be formed from a material having a larger coefficient of thermal expansion than a material forming the converging flow joint insert receiver 136. As such, during use when the converging flow joint insert 120 and the converging flow joint insert receiver 136 are exposed to the hot combustion gases, the converging flow joint insert 120 will thermally expand at a faster rate than the converging flow joint insert receiver 136. As such, the converging flow joint insert 120 will be placed under at least a partial load formed from a compressive load, which partially alleviates the compressive load and stress placed on the converging flow joint insert receiver 136 and surrounding structure. The load and stress created in the converging flow joint insert 120 is less than at a trailing edge in a conventional system without a converging flow joint insert 120. This is beneficial because stresses are transferred from the permanent/high cost material forming the converging flow joint insert receiver 136 and related

components to the modular, disposable converging flow joint insert 120.

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