A turbine blade includes an airfoil and a shroud coupled to a tip of the airfoil. The shroud includes a mid portion positioned directly above the tip of the airfoil. The mid portion includes a ramped radially outer surface extending from a first edge to a second edge in the direction from a pressure
A turbine blade includes an airfoil and a shroud coupled to a tip of the airfoil. The shroud includes a mid portion positioned directly above the tip of the airfoil. The mid portion includes a ramped radially outer surface extending from a first edge to a second edge in the direction from a pressure side toward a suction side of the airfoil, the second edge being positioned further radially inward than the first edge. In a first aspect, the shroud may include a curved pressure side portion positioned upstream of the pressure side of the airfoil, the pressure side portion being curved radially inward. In a second aspect, the shroud may include a curved suction side portion positioned downstream of the suction side of the airfoil, the suction side portion being curved radially outward.
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1. A turbine blade comprising: a generally elongated airfoil having a leading edge, a trailing edge, a pressure side and a suction side on a side opposite to the pressure side,a shroud coupled to a tip of the airfoil at a radially outer end of the airfoil, wherein the shroud extends in a direction g
1. A turbine blade comprising: a generally elongated airfoil having a leading edge, a trailing edge, a pressure side and a suction side on a side opposite to the pressure side,a shroud coupled to a tip of the airfoil at a radially outer end of the airfoil, wherein the shroud extends in a direction generally from the pressure side toward the suction side and extends circumferentially in a turbine engine, wherein a knife edge seal extends radially outward from the shroud,the shroud comprising: a mid portion positioned directly over the tip of the airfoil and comprising a ramped radially outer surface extending from a first edge to a second edge in the direction from the pressure side toward the suction side, the second edge being positioned further radially inward than the first edge, anda pressure side portion positioned upstream of the pressure side of the airfoil and extending from the first edge to a pressure side edge of the shroud, the pressure side portion being curved radially inward, wherein a radially inner surface of the pressure side portion forms a concave surface and a radially outer surface of the pressure side portion forms a convex surface, the pressure side edge being positioned further radially inward than the first edge. 2. The turbine blade according to claim 1, wherein a plurality of coolant ejection holes are positioned on the ramped radially outer surface of the mid portion, the plurality of coolant ejection holes being connected fluidically to an interior of the airfoil. 3. The turbine blade according to claim 1, wherein the mid portion is formed by a cutout defining a region of reduced mass of the shroud over the tip of the airfoil. 4. The turbine blade according to claim 1, wherein the second edge is generally aligned with a contour of the suction side at the tip of the airfoil, and the first edge is generally aligned with a contour of the pressure side at the tip of the airfoil. 5. The turbine blade according to claim 1, wherein the radially inner surface and the radially outer surface of the pressure side portion are connected at the pressure side edge of the shroud. 6. The turbine blade according to claim 1, wherein the shroud has a forward section extending from the knife edge seal toward the leading edge and an aft section extending from the knife edge seal toward the trailing edge, wherein the mid portion and the pressure side portion are positioned at the forward section of the shroud. 7. The turbine blade according to claim 1, wherein the mid portion of the shroud further includes a wall surface extending radially outward from the second edge to a third edge. 8. The turbine blade according to claim 7, wherein the ramped radially outer surface makes an angle with the wall surface, the angle varying in a direction from the leading edge to the trailing edge as a function of a profile of the airfoil at the tip. 9. The turbine blade according to claim 7, wherein the shroud further comprises a suction side portion positioned downstream of the suction side of the airfoil, the suction side portion extending from the third edge to a suction side edge of the shroud, the suction side portion being curved radially outward, wherein a radially inner surface of the suction side portion forms a convex surface and a radially outer surface of the suction side portion forms a concave surface, the suction side edge being positioned further radially outward than the third edge. 10. A turbine blade comprising: a generally elongated airfoil having a leading edge, a trailing edge, a pressure side and a suction side on a side opposite to the pressure side,a shroud coupled to a tip of the airfoil at a radially outer end of the airfoil, wherein the shroud extends in a direction generally from the pressure side toward the suction side and extends circumferentially in a turbine engine, wherein a knife edge seal extends radially outward from the shroud,the shroud comprising: a mid portion positioned directly over the tip of the airfoil and comprising a ramped radially outer surface extending from a first edge to a second edge in the direction from the pressure side toward the suction side, the second edge being positioned further radially inward than the first edge, the mid portion further including a wall surface extending radially outward from the second edge to a third edge, anda suction side portion positioned downstream of the suction side of the airfoil, the suction side portion extending from the third edge to a suction side edge of the shroud, the suction side portion being curved radially outward, wherein a radially inner surface of the suction side portion forms a convex surface and a radially outer surface of the suction side portion forms a concave surface, the suction side edge being positioned further radially outward than the third edge. 11. The turbine blade according to claim 10, wherein a plurality of coolant ejection holes are positioned on the ramped radially outer surface of the mid portion, the plurality of coolant ejection holes being connected fluidically to an interior of the airfoil. 12. The turbine blade according to claim 10, wherein the mid portion is formed by a cutout defining a region of reduced mass of the shroud over the tip of the airfoil. 13. The turbine blade according to claim 10, wherein the second edge is generally aligned with a contour of the suction side at the tip of the airfoil, and the first edge is generally aligned with a contour of the pressure side at the tip of the airfoil. 14. The turbine blade according to claim 10, wherein the radially inner surface and the radially outer surface of the suction side portion are connected at the suction side edge of the shroud. 15. The turbine blade according to claim 10, wherein the shroud has a forward section extending from the knife edge seal toward the leading edge and an aft section extending from the knife edge seal toward the trailing edge, wherein the mid portion and the suction side portion are positioned at the forward section of the shroud. 16. The turbine blade according to claim 10, wherein the ramped radially outer surface makes an angle with the wall surface, the angle varying in a direction from the leading edge to the trailing edge as a function of a profile of the airfoil at the tip. 17. The turbine blade according to claim 10, wherein the suction side edge of the shroud intersects the knife edge seal at 40-60% of a radial height of the knife edge seal. 18. A turbine stage comprising: a row of turbine blades arranged circumferentially spaced apart to define respective passages therebetween for channeling a main gas flow,each turbine blade comprising: a generally elongated airfoil having a leading edge, a trailing edge, a pressure side and a suction side on a side opposite to the pressure side,a shroud coupled to a tip of the airfoil at a radially outer end of the airfoil, wherein the shroud extends in a direction generally from the pressure side toward the suction side and extends circumferentially in the turbine stage, wherein a knife edge seal extends radially outward from the shroud,the shroud of each blade comprising: a mid portion positioned directly over the tip of the airfoil and comprising a ramped radially outer surface extending from a first edge to a second edge in the direction from the pressure side toward the suction side, the second edge being positioned further radially inward than the first edge, the mid portion further including a wall surface extending radially outward from the second edge to a third edge,a pressure side portion positioned upstream of the pressure side of the airfoil and extending from the first edge to a pressure side shroud edge, the pressure side portion being curved radially inward, wherein a radially inner surface of the pressure side portion forms a concave surface and a radially outer surface of the pressure side portion forms a convex surface, the pressure side shroud edge being positioned further radially inward than the first edge, anda suction side portion positioned downstream of the suction side of the airfoil and extending from the third edge to a suction side shroud edge, the suction side portion being curved radially outward, wherein a radially inner surface of the suction side portion forms a convex surface and a radially outer surface of the suction side portion forms a concave surface, the suction side shroud edge being positioned further radially outward than the third edge,wherein a circumferential gap is defined between the suction side shroud edge of a first turbine blade and the pressure side shroud edge of a circumferentially adjacent second turbine blade. 19. The turbine stage according to claim 18, wherein a plurality of coolant ejection holes are positioned on the ramped radially outer surface of the mid portion of each shroud, the plurality of coolant ejection holes being connected fluidically to an interior of the airfoil. 20. The turbine stage according to claim 18, wherein each shroud has a forward section extending from the knife edge seal toward the leading edge of the respective airfoil and an aft section extending from the knife edge seal toward the trailing edge of the respective airfoil, wherein the mid portion, pressure side portion and the suction side portion of each shroud are positioned at the forward section of the respective shroud.
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Cabra, Henry; Thomas, Sylvia W., Mini notched turbine generator.
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