A rotational duct blocker for a gas turbine engine includes a duct blocker rotor and a duct blocker stator. The duct blocker rotor includes a plurality of first vane segments that extend radially between an inner rotor platform and an outer rotor platform, and a plurality of first flow apertures that extend axially through the duct blocker rotor. Each first flow aperture also extends circumferentially between respective adjacent first vane segments. The duct blocker stator includes a plurality of second vane segments that extend radially between an inner stator platform and an outer stator platform, and a plurality of second flow apertures that extend axially through the duct blocker stator. Each second flow aperture also extends circumferentially between respective adjacent second vane segments. The first vane segments move circumferentially relative to the second vane segments to regulate fluid flowing between the first flow apertures and the second flow apertures.