US Patent 7775758 Impeller rear cavity thrust adjustor

An apparatus for adjusting a thrust load on a rotor assembly of a gas turbine engine includes an impeller rear cavity defined between a rear face of an impeller of the rotor assembly and a stationary wall spaced axially apart from the rear surface of the impeller. A pressurized air flow with a tangential velocity is introduced into the impeller rear cavity at a tip of the impeller to pressurize the cavity. Means are provided in the cavity for directly interfering with the tangential velocity of the pressurized air flow to affect an average static pressure of the pressurized air flow within the cavity in order to adjust the thrust load on the rotor assembly caused by the average static pressure in the cavity.