Duct assembly including helicoidal structure and gas turbine combustor including the same
A helicoidal structure promotes cooling of a liner applied in an annular space of a double-shell structure formed of the liner and a flow sleeve to cool a duct assembly, by increasing the residence time and cooling area of cooling compressed air on the surface of the liner. The helicoidal structure includes a helicoidal rib protruding from a surface of the liner to guide the cooling compressed air at a predetermined angle with respect to an axial direction of the liner, the helicoidal rib having cooling holes and forming a first cooling passage along which main-cooling compressed air flows and a second cooling passage along which auxiliary-cooling compressed air flows. The second cooling passage induces a flow of the auxiliary-cooling compressed air through the cooling holes, and the flow of the auxiliary-cooling compressed air is derived from a flow of the main-cooling compressed air in the first cooling passage.
1. A helicoidal structure for promoting cooling of a liner applied in an annular space of a double-shell structure formed of the liner and a flow sleeve, the helicoidal structure comprising:
a helicoidal rib including a continuous wall forming a first cooling passage along which main-cooling compressed air flows, the continuous wall comprising:
an upper edge forming an upper junction with an inner circumferential surface of the flow sleeve,
a lower edge forming a lower junction with an outer circumferential surface of the liner, and
a plurality of cooling holes formed in at least one of the upper and lower edges of the continuous wall, each of the plurality of cooling holes extending only part way from one of the upper and lower edges to the other of the upper and lower edges,
wherein the helicoidal rib is configured to guide the main-cooling compressed air at a predetermined angle with respect to an axial direction of the liner, and
wherein the plurality of cooling holes form a second cooling passage extending in the axial direction, the second cooling passage inducing a flow of an he auxiliary-cooling compressed air through the plurality of cooling holes, the flow of the auxiliary-cooling compressed air is derived from a flow of the main-cooling compressed air in the first cooling passage.
2. The helicoidal structure according to claim 1 , wherein the plurality of cooling holes are formed in each of the upper and lower edges of the continuous wall of the helicoidal rib.
3. The helicoidal structure according to claim 1 , wherein the plurality of cooling holes are alternately formed in the upper and lower edges of the continuous wall of the helicoidal rib along the axial direction.
4. The helicoidal structure according to claim 2 , wherein the plurality of cooling holes are formed at misaligned positions in respective portions of the continuous wall of the helicoidal rib with respect to the axial direction.
5. The helicoidal structure according to claim 1 , wherein the plurality of cooling holes are formed at positions spaced apart from each other by a predetermined distance along the continuous wall of the helicoidal rib.
6. The helicoidal structure according to claim 5 , wherein the plurality of cooling holes are alternately formed in the upper and lower edges of the continuous wall of the helicoidal rib along the axial direction.
7. The helicoidal structure according to claim 1 , wherein the continuous wall of the helicoidal rib is formed with constant width and height and formed to coil of the liner at least two times, so that the second cooling passage passes through the continuous wall of the helicoidal rib at least two times.
8. The helicoidal structure according to claim 1 , wherein each of the plurality of cooling holes has a semi-circular shape.
9. A combustor for a gas turbine, comprising:
a transition piece;
a liner coupled with the transition piece;
a flow sleeve configured to enclose a periphery of the transition piece and the liner; and
a helicoidal rib including a continuous wall forming a first cooling passage along which main-cooling compressed air flows, the continuous wall comprising:
an upper edge forming an upper junction with an inner circumferential surface of the flow sleeve,
a lower edge forming a lower junction with an outer circumferential surface of the liner, and
a plurality of cooling holes formed in at least one of the upper and lower edges of the continuous wall, each of the plurality of cooling holes extending only part way from one of the upper and lower edges to the other of the upper and lower edges,
wherein the helicoidal rib is configured to guide the main-cooling compressed air at a predetermined angle with respect to an axial direction of the liner, and
wherein the plurality of cooling holes form a second cooling passage extending in the axial direction, the second cooling passage inducing a flow of an he auxiliary-cooling compressed air through the plurality of cooling holes, the flow of the auxiliary-cooling compressed air is derived from a flow of the main-cooling compressed air in the first cooling passage.
10. The combustor according to claim 9 , wherein the plurality of cooling holes are formed in each of the upper and lower edges of the continuous wall of the helicoidal rib.
11. The combustor according to claim 10 , wherein the plurality of cooling holes are alternately formed in the upper and lower edges of the continuous wall of the helicoidal rib along the axial direction.
12. The combustor according to claim 10 , wherein the plurality of cooling holes are formed at misaligned positions in respective portions of the continuous wall of the helicoidal rib with respect to the axial direction.
13. The combustor according to claim 9 , wherein the plurality of cooling holes are formed at positions spaced apart from each other by a predetermined distance along the continuous wall of the helicoidal rib.
14. The combustor according to claim 13 , wherein the plurality of cooling holes are alternately formed in the upper and lower edges of the continuous wall of the helicoidal rib along the axial direction.
15. The combustor according to claim 9 , wherein the continuous wall of the helicoidal rib is formed with constant width and height and formed to coil of the liner at least two times, so that the second cooling passage passes through the continuous wall of the helicoidal rib at least two times.
16. The combustor according to claim 9 , wherein each of the plurality of cooling holes has a semi-circular shape.
17. A gas turbine for generating power, comprising a combustor comprising:
a transition piece;
a liner coupled with the transition piece;
a flow sleeve configured to enclose a periphery of the transition piece and the liner; and
a helicoidal rib including a continuous wall forming a first cooling passage along which main-cooling compressed air flows, the continuous wall comprising:
an upper edge forming an upper junction with an inner circumferential surface of the flow sleeve,
a lower edge forming a lower junction with an outer circumferential surface of the liner, and
a plurality of cooling holes formed in at least one of the upper and lower edges of the continuous wall, each of the plurality of cooling holes extending only part way from one of the upper and lower edges to the other of the upper and lower edges,
wherein the helicoidal rib is configured to guide the main-cooling compressed air at a predetermined angle with respect to an axial direction of the liner, and
wherein the plurality of cooling holes form a second cooling passage extending in the axial direction, the second cooling passage inducing a flow of an auxiliary-cooling compressed air through the plurality of cooling holes, the flow of the auxiliary-cooling compressed air is derived from a flow of the main-cooling compressed air in the first cooling passage.
18. The gas turbine according to claim 17 , wherein the plurality of cooling holes are formed in each of the upper and lower edges of the continuous wall of the helicoidal rib.
19. The gas turbine according to claim 18 , wherein the plurality of cooling holes are alternately formed in the upper and lower edges of the continuous wall of the helicoidal rib along the axial direction.
20. The gas turbine according to claim 18 , wherein the plurality of cooling holes are formed at misaligned positions in respective portions of the continuous wall of the helicoidal rib with respect to the axial direction.