Turbine bucket for control of wheelspace purge air

A turbine bucket comprising:

• a platform portion;
• a shank portion extending radially inward from the platform portion and at least one angel wing extending axially from a face of the shank portion;
• an airfoil extending radially outward from the platform portion;
• an arcuate platform lip extending axially from the platform portion, the arcuate platform lip extending outward toward the airfoil to an upturned distal end;
• a plurality of column members disposed in spaced relationship along the upturned distal end of the platform lip, wherein each column member consists of a top and four walls joined to the top, and wherein adjacent pairs of the plurality of column members define a plurality of voids therebetween;
• the plurality of voids extending to a substantially uniform depth across the walls of the column members that define the voids in circumferential and axial directions;
• wherein each wall is substantially perpendicular to the upturned distal end;
• and
• wherein, in an operative state, the plurality of voids is adapted to change a swirl velocity of purge air between the platform lip and the at least one angel wing.