A turbomachine includes a rotor assembly including a wheel member. The wheel member includes a first portion that extends to a second portion through an intermediate portion. The intermediate portion partially defines a first wheel space and a second wheel space. The wheel member further includes a rotor inertia belt member arranged at the second portion. The rotor inertia belt member includes an extraction air cavity. The extraction air cavity includes an inlet, a first plurality of extraction air passages each including an inlet section and an outlet section, the outlet section leading into the first wheel space, and a second plurality of extraction air passages each including an inlet portion and an outlet portion, the outlet portion leading into the second wheel space.