Light weight steam turbine blade

Claim 2

A steam turbine comprising a stationary cylinder for containing a steam flow, and a rotor enclosed by the cylinder, and a row of blades, each of said blades having a root portion attached to said rotor and an airfoil portion, each of said airfoil portions having: a) a base portion and a tip portion defining an airfoil height therebetween; b) a rounded leading edge portion and a trailing edge portion; c) a pressure surface and a generally concave suction surface extending between said rounded leading edge portion and said trailing edge portion and defining a thickness of said airfoil therebetween, (i) each of said airfoils having first, second and third transverse sections disposed radially outward from said root by distances equal to approximately 25%, 50% and 75%, respectively, of said height of said airfoil, a first portion of said airfoil height extending between said first and third sections, and (ii) said pressure surface over at least said first portion of said airfoil height having a curvature undergoing an inflection at a location disposed within said pressure surface, a first portion of said pressure surface extending over said first portion of said airfoil height having a concave curvature and being disposed between said inflection location and said rounded leading edge portion, a second portion of said pressure surface extending over said first portion of said airfoil height having a convex curvature and being disposed between said inflection location and said trailing edge, said concave curvature in said first portion of said pressure surface having a maximum negative value greater than -1.0 mm -1 ×10 -2 , and said convex curvature in said second portion of said pressure surface having a maximum positive value greater than 1.0 mm -1 ×10 -2 .

Claim 3

A steam turbine comprising a stationary cylinder for containing a steam flow, and a rotor enclosed by the cylinder, and a row of blades, each of said blades having a root portion attached to said rotor and an airfoil portion, each of said airfoil portions having: a) a base portion and a tip portion defining an airfoil height therebetween; b) a leading edge portion and a trailing edge portion; c) pressure and suction surfaces extending between said leading edge and trailing edge portions and defining a thickness of said airfoil therebetween, (i) each of said airfoils having first, second and third transverse sections disposed radially outward from said root by distances equal to approximately 25%, 50% and 75%, respectively, of said height of said airfoil, a first portion of said airfoil height extending between said first and third sections, and (ii) said pressure surface over at least said first portion of said airfoil height having a curvature undergoing an inflection at a location thereon, a first portion of said pressure surface disposed upstream of said inflection location and a second portion of said pressure surface disposed downstream of said inflection location, said pressure surface having a concave curvature in said first portion and a convex curvature in said second portion; and d) each of said airfoils being defined by the following parameters having approximately the values indicated below, all angles being expressed in degrees: ______________________________________ 25% 50% 75% Percent Height Section Section Section ______________________________________ Radius (cm) 85.2 87.8 90.4 Width (cm) 3.6 3.2 2.9 Pitch/Width Ratio 1.20 1.39 1.59 Pitch/Cord Ratio 0.69 0.73 0.76 Stagger Angle 53.8 57.7 61.1 Maximum Thickness (mm) 13.6 10.4 7.8 Max Thickness/Cord 0.22 0.17 0.13 Camber Angle 67.9 53.7 42.4 Exit Opening (mm) 10.1 10.7 11.3 Inlet Metal Angle 97.9 112.4 123.8 Inlet Included Angle 67.3 52.1 33.8 Suction Surface 11.2 13.3 14.9 Turning Angle ______________________________________

Claim 4

A steam turbine comprising a stationary cylinder for containing a steam flow, and a rotor enclosed by the cylinder, and a row of blades, each of said blades having a root portion attached to said rotor and an airfoil portion, each of said airfoil portions having: a) a base portion and a tip portion defining an airfoil height therebetween; b) a leading edge portion and a trailing edge portion; c) pressure and suction surfaces extending between said leading edge and trailing edge portions and defining a thickness of said airfoil therebetween, (i) each of said airfoils having first, second and third transverse sections disposed radially outward from said root by distances equal to approximately 25%, 50% and 75%, respectively, of said height of said airfoil, a first portion of said airfoil height extending between said first and third sections, and (ii) said pressure surface over at least said first portion of said airfoil height having a curvature undergoing an inflection at a location thereon, a first portion of said pressure surface disposed upstream of said inflection location and a second portion of said pressure surface disposed downstream of said inflection location, said pressure surface having a concave curvature in said first portion and a convex curvature in said second portion; and d) each of said airfoils being defined by the following parameters having approximately the values indicated below, all angles being expressed in degrees: ______________________________________ 25% 50% 75% Percent Height Section Section Section ______________________________________ Radius (cm) 85.2 87.8 90.4 Width (cm) 3.6 3.2 2.9 Pitch/Width Ratio 1.20 1.39 1.59 Pitch/Cord Ratio 0.69 0.73 0.76 Stagger Angle 53.8 57.7 61.1 Maximum Thickness (mm) 13.6 10.4 7.8 Max Thickness/Cord 0.22 0.17 0.13 Camber Angle 67.9 53.7 42.4 Exit Opening (mm) 10.1 10.7 11.3 Inlet Metal Angle 97.9 112.4 123.8 Inlet Included Angle 67.3 52.1 33.8 Suction Surface 11.2 13.3 14.9 Turning Angle ______________________________________

Claim 5

A steam turbine comprising a stationary cylinder for containing a steam flow, and a rotor enclosed by the cylinder, and a row of blades, each of said blades having a root portion attached to said rotor and an airfoil portion, each of said airfoil portions having: a) a base portion and a tip portion defining an airfoil height therebetween; b) a leading edge portion and a trailing edge portion; c) pressure and suction surfaces extending between said leading edge and trailing edge portions and defining a thickness of said airfoil therebetween, (i) each of said airfoils having first, second and third transverse sections disposed radially outward from said root by distances equal to approximately 25%, 50% and 75%, respectively, of said height of said airfoil, a first portion of said airfoil height extending between said first and third sections, and (ii) said pressure surface over at least said first portion of said airfoil height having a curvature undergoing an inflection at a location thereon, a first portion of said pressure surface disposed upstream of said inflection location and a second portion of said pressure surface disposed downstream of said inflection location, said pressure surface having a concave curvature in said first portion and a convex curvature in said second portion, said pressure surface having a curvature at said first, second and third transverse sections as follows, the locations 0% through 100% referring to distances by which each respective location is displaced from said trailing edge portion along said pressure surface expressed as a percentage of the total distance along said pressure surface from said trailing edge portion to said leading edge portion: ______________________________________ Pressure Surface Curvature, mm.sup.-1 (×10.sup.-2) 25% 50% 75% Location Section Section Section ______________________________________ 0% 0.4 0.5 0.2 10% 0.3 0.5 0.2 20% 0.8 0.7 0.5 30% 1.3 0.9 0.7 40% 1.7 1.1 1.1 50% 1.6 1.4 1.2 60% 1.4 1.6 1.4 70% 1.8 1.6 1.3 80% 2.0 1.4 1.1 90% -1.1 -1.0 -0.3 100% -2.6 -2.5 -1.3 ______________________________________

Claim 6

A steam turbine comprising a stationary cylinder for containing a steam flow, and a rotor enclosed by the cylinder, and a row of blades, each of said blades having a root portion attached to said rotor and an airfoil portion, each of said airfoil portions having: a) a base portion and a tip portion defining an airfoil height therebetween; b) a leading edge portion and a trailing edge portion; c) pressure and suction surfaces extending between said leading edge and trailing edge portions and defining a thickness of said airfoil therebetween, (i) each of said airfoils having first, second and third transverse sections disposed radially outward from said root by distances equal to approximately 25%, 50% and 75%, respectively, of said height of said airfoil, a first portion of said airfoil height extending between said first and third sections, and (ii) said pressure surface over at least said first portion of said airfoil height having a curvature undergoing an inflection at a location thereon, a first portion of said pressure surface disposed upstream of said inflection location and a second portion of said pressure surface disposed downstream of said inflection location, said pressure surface having a concave curvature in said first portion and a convex curvature in said second portion, said pressure surface having a curvature at said first, second and third transverse sections as follows, the locations 0% through 100% referring to distances by which each respective location is displaced from said trailing edge portion along said pressure surface expressed as a percentage of the total distance along said pressure surface from said trailing edge portion to said leading edge portion: ______________________________________ Pressure Surface Curvature, mm.sup.-1 (×10.sup.-2) 25% 50% 75% Location Section Section Section ______________________________________ 0% 0.4 0.5 0.2 10% 0.3 0.5 0.2 20% 0.8 0.7 0.5 30% 1.3 0.9 0.7 40% 1.7 1.1 1.1 50% 1.6 1.4 1.2 60% 1.4 1.6 1.4 70% 1.8 1.6 1.3 80% 2.0 1.4 1.1 90% -1.1 -1.0 -0.3 100% -2.6 -2.5 -1.3 ______________________________________

Claim 7

The steam turbine according to claim 3, wherein said suction surface has a curvature at said first, second and third transverse sections as follows, the locations 0% through 100% referring to distances by which each respective location is displaced from said trailing edge portion along said suction surface expressed as a percentage of the total distance along said suction surface from said trailing edge portion to said leading edge portion: ______________________________________ Suction Surface Curvature, mm.sup.-1 (×10.sup.-2) 25% 50% 75% Location Section Section Section ______________________________________ 0% 0.2 0.2 0.2 10% 0.2 0.2 0.2 20% 0.3 0.2 0.2 30% 0.3 0.3 0.3 40% 0.3 0.3 0.3 50% 1.2 1.1 0.9 60% 1.9 1.7 1.1 70% 4.5 4.1 4.4 80% 6.9 6.0 4.9 90% 7.1 5.9 3.9 100% 1.7 2.2 1.2 ______________________________________

Claim 8

In a steam turbine, a row of blades comprising an airfoil for each blade, each of said airfoils (i) having a base portion and a tip portion defining an airfoil height therebetween, (ii) having transverse sections disposed radially outward from said base by distances equal to 25%, 50% and 75%, respectively, of said height of said airfoil, and (iii) defined by the following parameters having approximately the values indicated below, all angles being expressed in degrees: ______________________________________ 25% 50% 75% Percent Height Section Section Section ______________________________________ Width (cm) 3.6 3.2 2.9 Pitch/Width Ratio 1.20 1.39 1.59 Pitch/Cord Ratio 0.69 0.73 0.76 Stagger Angle 53.8 57.7 61.1 Maximum Thickness (mm) 13.6 10.4 7.8 Max Thickness/Cord 0.22 0.17 0.13 Camber Angle 67.9 53.7 42.4 Exit Opening (mm) 10.1 10.7 11.3 Inlet Metal Angle 97.9 112.4 123.8 Inlet Included Angle 67.3 52.1 33.8 Suction Surface 11.2 13.3 14.9 Turning Angle ______________________________________

Claim 9

In a steam turbine, a row of blades comprising an airfoil for each blade, each of said airfoils (i) having a base portion and a tip portion defining an airfoil height therebetween, (ii) having transverse sections disposed radially outward from said base by distances equal to 25%, 50% and 75%, respectively, of said height of said airfoil, and (iii) defined by the following parameters having approximately the values indicated below, all angles being expressed in degrees: ______________________________________ 25% 50% 75% Percent Height Section Section Section ______________________________________ Width (cm) 3.6 3.2 2.9 Pitch/Width Ratio 1.20 1.39 1.59 Pitch/Cord Ratio 0.69 0.73 0.76 Stagger Angle 53.8 57.7 61.1 Maximum Thickness (mm) 13.6 10.4 7.8 Max Thickness/Cord 0.22 0.17 0.13 Camber Angle 67.9 53.7 42.4 Exit Opening (mm) 10.1 10.7 11.3 Inlet Metal Angle 97.9 112.4 123.8 Inlet Included Angle 67.3 52.1 33.8 Suction Surface 11.2 13.3 14.9 Turning Angle ______________________________________

Claim 10

In a steam turbine, a row of blades, each of said blades having a root portion and an airfoil portion, each of said airfoil portions having (i) a base portion and a tip portion defining an airfoil height therebetween, (ii) a leading edge portion and a trailing edge portion, (iii) pressure and suction surfaces extending between said leading edge and trailing edge portions and defining a thickness of said airfoil therebetween, (iv) transverse sections disposed radially outward from said root by distances equal to 25%, 50% and 75%, respectively, of said height of said airfoil, said pressure surface having a curvature at said base and tip portions and at said 25%, 50% and 75% sections as follows, the locations 0% through 100% referring to distances by which each respective location is displaced from said trailing edge portion along said pressure surface expressed as a percentage of the total distance along said pressure surface from said trailing edge portion to said leading edge portion: ______________________________________ Pressure Surface Curvature, mm.sup.-1 (×10.sup.-2) Base 25% 50% 75% Tip Location Section Section Section Section Section ______________________________________ 0% 1.0 0.4 0.5 0.2 0.2 10% 1.0 0.3 0.5 0.2 0.2 20% 1.2 0.8 0.7 0.5 0.4 30% 1.3 1.3 0.9 0.7 0.5 40% 1.4 1.7 1.1 1.1 0.6 50% 1.6 1.6 1.4 1.2 0.9 60% 1.7 1.4 1.6 1.4 1.1 70% 1.9 1.8 1.6 1.3 1.4 80% 1.0 2.0 1.4 1.1 1.0 90% -0.3 -1.1 -1.0 -0.3 0.5 100% -0.9 -2.6 -2.5 -1.3 0.0 ______________________________________

Claim 11

In a steam turbine, a row of blades, each of said blades having a root portion and an airfoil portion, each of said airfoil portions having (i) a base portion and a tip portion defining an airfoil height therebetween, (ii) a leading edge portion and a trailing edge portion, (iii) pressure and suction surfaces extending between said leading edge and trailing edge portions and defining a thickness of said airfoil therebetween, (iv) transverse sections disposed radially outward from said root by distances equal to 25%, 50% and 75%, respectively, of said height of said airfoil, said pressure surface having a curvature at said base and tip portions and at said 25%, 50% and 75% sections as follows, the locations 0% through 100% referring to distances by which each respective location is displaced from said trailing edge portion along said pressure surface expressed as a percentage of the total distance along said pressure surface from said trailing edge portion to said leading edge portion: ______________________________________ Pressure Surface Curvature, mm.sup.-1 (×10.sup.-2) Base 25% 50% 75% Tip Location Section Section Section Section Section ______________________________________ 0% 1.0 0.4 0.5 0.2 0.2 10% 1.0 0.3 0.5 0.2 0.2 20% 1.2 0.8 0.7 0.5 0.4 30% 1.3 1.3 0.9 0.7 0.5 40% 1.4 1.7 1.1 1.1 0.6 50% 1.6 1.6 1.4 1.2 0.9 60% 1.7 1.4 1.6 1.4 1.1 70% 1.9 1.8 1.6 1.3 1.4 80% 1.0 2.0 1.4 1.1 1.0 90% -0.3 -1.1 -1.0 -0.3 0.5 100% -0.9 -2.6 -2.5 -1.3 0.0 ______________________________________

Claim 12

The row of blades according to claim 6, wherein said suction surface has a curvature at said base and tip portions and at said 25%, 50% and 75% sections as follows, the locations 0% through 100% referring to distances by which each respective location is displaced from said trailing edge portion along said suction surface expressed as a percentage of the total distance along said suction surface from said trailing edge portion to said leading edge portion: ______________________________________ Suction Surface Curvature, mm.sup.-1 (×10.sup.-2) Base 25% 50% 75% Tip Location Section Section Section Section Section ______________________________________ 0% 0.3 0.2 0.2 0.2 0.3 10% 0.3 0.2 0.2 0.2 0.3 20% 0.2 0.3 0.2 0.2 0.3 30% 0.3 0.3 0.3 0.3 0.3 40% 0.7 0.3 0.3 0.3 0.4 50% 1.0 1.2 1.1 0.9 0.5 60% 2.3 1.9 1.7 1.1 1.5 70% 5.8 4.5 4.1 4.4 2.7 80% 7.1 6.9 6.0 4.9 4.1 90% 6.5 7.1 5.9 3.9 3.6 100% 1.5 1.7 2.2 1.2 0.8 ______________________________________