Patent ID: 7396205
Filing Date: 2008-07-08
Classification: F01D,F05D,Y02T,Y10S

Abstract:
1. A rotor blade for a rotary machine having a flowpath for working medium gases, the rotor blade having an axis Ar and a tip region having a laterally extending seal land, which comprises: an airfoil having a stacking line which extends radially and a plurality of airfoil sections perpendicular to the stacking line which define the shape of the airfoil, each airfoil section having a leading edge, a trailing edge spaced chordwise from the leading edge, a leading edge region, a trailing edge region, a suction side, and a pressure side each extending from the leading edge to the trailing edge; and a tip shroud having a suction side wing and a pressure side wing extending from the sides of the airfoils, each wing having a side which generally faces in the lateral direction, and a beam having laterally facing sides which carries the seal land, the seal land extending radially outwardly from the beam, the beam being integral with the wings and extending between the wings to divide each wing into a front portion and a rear portion; and a transition zone which extends from the sides of the airfoil to provide a flow path surface of the shroud and to provide a transition from the material of the airfoil to the material of the shroud; wherein the rotor blade has a reference normal sectioning plane P passing through a point at the junction of the transition zone to the airfoil that contains a first line perpendicular to the side of the airfoil section at that junction point and a second line passing through that junction point that is perpendicular to the first line and parallel to the stacking line of the airfoil; wherein a transition line is the line of intersection of the plane P with the transition zone at a junction point and defines the surface contour of the transition zone at a particular location; wherein each transition line has an offset distance A from the airfoil which is the distance of the projection of the transition line along the first line of the Plane P perpendicular to the side of the airfoil section, has an offset distance B from the shroud which is the distance of the projection of the transition line along the second line of the sectioning plane parallel to the stacking line, and has an offset ratio which is the ratio of the offset distance A from the airfoil divided by the offset distance B from the shroud; wherein the transition zone covers over ninety-five (95) percent of the flow path area of the portions of the wines that are located between the leading edge region and the trailing edge region such that the transition zone over substantially all of its extent between the leading edge region and the trailing edge region extends to the sides of the wings with a cross-sectional shape at a location along a normal sectioning plane that is spanwisely tapered under a wing to the side of the wing and that is spanwisely tapered under the beam at least as far as the side of the immediately adjacent portion of the wing; wherein the cross-sectional shape of the transition zone has more than one type of curvature to reduce stresses in the rotor blade as compared to transition zones having one type of curvature for the transition zone and at least a portion of the transition zone extending to the rear portion of the wing on the suction side of the airfoil and on the pressure side of the airfoil changes to a location rearward of the beam at which the surface of the transition zone at a particular transition line has an offset ratio R rounded to the nearest hundredth that lies in a range of ninety-nine one hundredths to one hundred and three hundredths (0.99≦R≦1.03) such that the degree of being circular for the transition line includes circular and nearly circular configurations for the transition line.