Impeller rear cavity thrust adjustor
View Patent ↗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.
1. An apparatus for adjusting a thrust load on a rotor assembly of a gas turbine engine, the rotor assembly including a compressor having an impeller for pressurizing air in the engine, the apparatus comprising:
an impeller rear cavity defined between a rear face of the impeller and a stationary wall spaced axially apart from the rear face of the impeller, the impeller rear cavity being in fluid communication at a tip of the impeller with pressurized air from the impeller tip to introduce a pressurized air flow with a tangential velocity from the impeller tip into the impeller rear cavity; and
a plurality of circumferentially spaced interfering members affixed within the impeller rear cavity and protruding from the stationary wall into the impeller rear 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 impeller rear cavity.
2. The apparatus as defined in claim 1 wherein the interfering members are located radially adjacent to the impeller tip in the impeller rear cavity.
3. The apparatus as defined in claim 1 wherein the interfering members each extend radially.
4. The apparatus as defined in claim 1 wherein the impeller rear cavity is in fluid communication at a location radially, inwardly away from the impeller tip, with a low pressure region for extracting an air flow from the impeller cavity.
5. A gas turbine engine comprising:
a rotor assembly including a shaft, a turbine and a compressor affixed to the shaft, the compressor having an impeller for pressurizing air in the engine;
a combustion section in fluid communication with pressurized air from the compressor;
a cavity defined between a rear face of the impeller and a stationary wall spaced axially apart from the rear face of the impeller, the cavity being in fluid communication at a tip of the impeller with pressurized air from the impeller tip to introduce a pressurized air flow with a tangential velocity from the impeller tip into the cavity, the cavity being in fluid communication at a location radially, inwardly away from the impeller tip with a low pressure region for extracting an air flow from the cavity; and
a plurality of holes extending axially and tangentially through the stationary wall and being in fluid communication with the combustion section for directing a pressurized air flow from the combustion section into the cavity in a direction substantially opposite to the tangential velocity of the pressurized air flow from the impeller tip into the cavity to reduce the tangential velocity of the pressurized air flow within the cavity.
6. The gas turbine engine as defined in claim 5 therein the holes are circumferentially spaced apart one from another.
7. The gas turbine engine as defined in claim 5 wherein the holes are located radially adjacent to the impeller tip.
8. A method for adjusting a thrust load on a rotor assembly of a gas turbine engine, the rotor assembly including a compressor having an impeller for pressurizing air in the engine, the compressor defining a cavity between a rear face of the impeller and a stationary wall spaced axially apart from the rear face of the impeller, to introduce a pressurized air flow with a tangential velocity from the impeller tip into the cavity, the method comprising a step of injecting a high pressure air flow through at least one opening in the stationary wall into the cavity in a direction selected to be substantially the same as or opposite to a direction of the tangential velocity of the pressurized air flow introduced from the impeller tip into the cavity, depending on a desired adjustment result of the thrust load.
9. The method as defined in claim 8 wherein the selected direction is substantially the same as the direction of the tangential velocity of the pressurized air flow introduced from the impeller tip into the cavity in order to decrease the thrust load on the rotor assembly.
10. The method as defined in claim 8 wherein the selected direction is substantially opposite to the direction of the tangential velocity of the pressurized air flow introduced from the impeller tip into the cavity in order to increase the thrust load on the rotor assembly.