Last Stage Blade Design to Reduce Turndown Vibration
OwnerAlan Donn Maddausinventor
Life of this patent
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Abstract
A turbine bucket includes a bucket airfoil having a cross-section in an airfoil shape. The bucket is twisted from a root end to a tip end. A degree of twist defines an accumulated angular offset of the tip end in a range of 10-15° relative to a tangential direction, thereby reducing excess negative incidence by 15-20° relative to the tangential direction.
Claims18
A turbine bucket including a bucket airfoil having a cross-section in an airfoil shape, the turbine bucket being twisted from a root end to a tip end, wherein a degree of twist defines an accumulated angular offset of the tip end in a range of 10-15° relative to a tangential direction, thereby reducing excess negative incidence by 15-20° relative to the tangential direction.
A turbine comprising:
- a rotor;
- a rotatable shaft that rotates with the rotor;
- and
- a turbine coupled with the rotatable shaft and the rotor, the turbine including a plurality of axially spaced rotor wheels, wherein a plurality of buckets are coupled with each rotor wheel, each of the buckets having a cross-section in an airfoil shape, wherein a last stage bucket is twisted from a root end to a tip end, and wherein a degree of twist defines an accumulated angular offset of the tip end in a range of 10-15° relative to a tangential direction, thereby reducing excess negative incidence by 15-20° relative to the tangential direction.
A method of reducing flow induced vibration in a last stage turbine bucket, the turbine bucket being twisted from a root end to a tip end, the method comprising twisting the turbine bucket to a degree that defines an accumulated angular offset of the tip end in a range of 10-15° relative to a tangential direction, thereby reducing excess negative incidence by 15-20° relative to the tangential direction.
Dependencies are inferred from the claim text.