Method of operating adaptive core engines
A method of operating a compressor in an adaptive core engine is disclosed. The method comprises the steps of operating a front block compressor to increase pressure of a fluid to a first pressure ratio in a high-power mode operation; operating a rear block compressor coupled to the front block compressor such that the front block compressor and the rear block compressor operate at the same physical speed; closing a rear block stator vane located axially forward from the rear block compressor such that the flow of the fluid into the rear block compressor is substantially cut off; and keeping a blocker door opened such that substantially all of the fluid pressurized by the front block compressor flows through a bypass passage during the high-power mode operation. The operation may be transitioned from the high-power mode to a low-power mode by opening a rear block stator such that the rear block compressor receives at least a portion of the fluid flowing from the front block compressor and maintains an overall engine pressure ratio.
1. A method of operating a compressor comprising the steps of:
operating a front block compressor of an adaptive core engine to increase pressure of a fluid to a first pressure ratio in a high-power mode operation;
operating a rear block compressor of the adaptive core engine coupled to the front block compressor such that the front block compressor and the rear block compressor operate at the same physical speed;
driving the front and rear block compressors with a high pressure turbine;
closing a rear block stator vane such that flow of the fluid into the rear block compressor is substantially cut off except for a purge flow during a high-power mode operation;
keeping a blocker door opened such that substantially all of the fluid pressurized by the front block compressor flows through a bypass passage during the high-power mode operation; and
flowing all of the fluid from the front and the rear block compressors into a combustor of the adaptive core engine upstream of a high pressure turbine of the adaptive core engine.
2. A method according to claim 1 further comprising the step of keeping a front block compressor stator vane substantially open.
3. A method according to claim 2 wherein the front block compressor stator vanes are scheduled to keep a front block corrected speed of the front block nearly constant.
4. A method according to claim 1 further comprising a step of transitioning the rear block compressor operation from the high-power mode to a low-power mode by opening a rear block stator vane such that the rear block compressor receives at least a portion of the fluid flowing from the front block compressor.
5. A method according to claim 4 wherein the step of transitioning includes substantially closing the blocker door.
6. A method according to claim 5 wherein the blocker door is operated to a closed position such that there is no reversal of flow in a bypass passage.
7. A method according to claim 3 wherein the blocker door is operated to a closed position such that there is no recirculation of flow in the rear block compressor.
8. A method according to claim 5 wherein the blocker door, rear block stator vane and front block stator vane are operated such that an overall pressure ratio in the low-power mode after transition is substantially the same as an overall pressure ratio in the high-power mode before the transition.
9. A method according to claim 4 wherein a variable area turbine nozzle is maintained in a substantially fixed position during the transition from high-power mode to a low-power mode.
10. A method according to claim 5 further comprising a step of reducing an area of a variable area high pressure turbine nozzle located downstream from the rear block compressor, thereby increasing a rear block pressure ratio.
11. A method according to claim 5 further comprising a step of reducing an area of a variable area low pressure turbine nozzle located downstream from the rear block compressor, thereby increasing a rear block pressure ratio.
12. A method according to claim 5 further comprising a step of reducing an area of an exhaust nozzle located downstream from the rear block compressor, thereby increasing a rear block pressure ratio.
13. A method according to claim 1 further comprising a step of opening a safety valve to release a portion of the flow in the bypass passage.