COOLED STATOR HEAT SHIELD
The present invention provides a stator heat shield for a gas turbine. The gas turbine includes a rotor defining an axis of rotation. The stator heat shield includes a plurality of cooling units disposed in array along the axis of rotation. Each of the cooling units includes an outside part facing hot gas path of the gas turbine, and an inside plate positioned on the outside part and exposed to cooling air, wherein the inside plate comprises a plurality of inlet openings formed through the inside plate to introduce the cooling air into the outside part and thereby impingement cooling of the hot gas washed wall of the outside part. The outside part includes a cooling air channel formed therein with a first central portion to receive the cooling air, and a second spiral portion around the first central portion to convey the cooling air outward to a cooling air outlet of the second spiral portion. Initial investigation of the proposed cooling scheme in the present invention shows that the cooling air saving of 40% is expected compared to the common design.
1 . A cooled stator heat shield for a gas turbine, the gas turbine having a rotor defining an axis of rotation, the stator heat shield comprising a plurality of cooling units disposed in array substantially along the axis of rotation and covering the whole hot gas exposed surface of the heat shield, wherein each of the cooling units comprises an outside part facing hot gas path of the gas turbine, and an inside plate positioned on the outside part and exposed to cooling air, and
wherein the inside plate comprises a plurality of inlet openings formed through the inside plate to introduce the cooling air into the outside part, thereby impingement cooling of the outside part,
the outside part comprises a cooling air channel formed therein with a first central portion to receive the cooling air and a second spiral portion around the first central portion to convey the cooling air outward to a cooling air outlet of the second spiral portion.
2 . The stator heat shield according to claim 1 , wherein in the cooling units positioned near the leading edge and trailing edge regions of the stator heat shield, the cooling air outlet is formed as a plurality of discharge holes through the undersurface of the outside part to feed the cooling air into the hot gas path.
3 . The stator heat shield according to claim 1 , wherein in the cooling units positioned near the leading edge and trailing edge regions of the stator heat shield, the cooling air outlet is formed as a plurality of film cooling holes through the undersurface of the outside part.
4 . The stator heat shield according to any of claim 1 , wherein a plurality of flow barrier elements are disposed inside the cooling air channel.
5 . The stator heat shield segment according to claim 4 , wherein the flow barrier elements are selected from the group consisting of plain ribs, V shaped ribs, W shaped ribs, pins, vortex generators and dimples.
6 . The stator heat shield according to any of claim 1 , wherein the stator heat shield is manufactured by casting or additive manufacturing method.
7 . The stator heat shield segment according to claim 6 , wherein the additive manufacturing method includes selective laser melting.
8 . A gas turbine comprising the stator heat shield according to claim 1 .