Re-entrant spaceblock configuration for enhancing cavity flow in rotor endwinding of electric power generator

A gas cooled dynamoelectric machine, comprising:

• a rotor having a spindle and a body portion;
• a rotor winding comprising axially extending coils disposed on said body portion and spaced, concentric endwindings extending axially beyond at least one end of said body portion, said endwindings and said spindle defining an annular space therebetween;
• a plurality of spaceblocks located between adjacent ones of said endwindings thereby to define a plurality of cavities, each bounded by adjacent spaceblocks and adjacent endwindings and open to said annular space;
• and
• each said spaceblock having first and second side walls engaging said adjacent endwindings, an upstream wall, and a downstream wall, said downstream wall of at least one of said spaceblocks having a non-planar contour to lower a suction pressure developed adjacent a trailing edge of the spaceblock to enhance cooling flow, wherein said non-planar downstream wall has a re-entrant contour to enhance rotating cavity cooling flow, wherein said non-planar downstream wall is defined as a generally part circular concave curve.