A dynamoelectric machine includes a rotor having a plurality of adjacent coils; a spaceblock disposed between adjacent coils to define at least one cavity adjacent the spaceblock and between mutually adjacent coils; and the spaceblock including a body having one of: a substantially T-shaped cross-section, a substantially hexagonal cross-section and a substantially truncated arrow cross-section, the cross-section providing at least one flow deflector structure on at least one cavity facing surface of the spaceblock for intercepting and redirecting circulating coolant flow in the cavity towards a central region of the at least one cavity.