A gas turbine engine includes a turbine section that has a disk rotatable about an axis. The disk has circumferentially-spaced blade mounting features and radially outer rim surfaces extending circumferentially between the blade mounting features. Turbine blades are mounted circumferentially around the disk in the blade mounting features. Seals are arranged radially outwards of the disk adjacent the radially outer rim surfaces such that there are respective passages between the seals and the radially outer rim surfaces. The radially outer rim surfaces include radially-extending protrusions that extend into the respective passages.