Performance envelope extension method for a gas turbine engine
First Claim
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1. A method of uniformly cooling a gas turbine engine having a spool, comprising the steps of:
- determining when the engine is shutdown;
turning on an auxiliary motor to rotate the spool after the engine is shutdown;
determining if an external force in preventing the auxiliary motor form rotating the spool;
turning off the auxiliary motor if such an external force is detected and allowing the external force to rotate the spool;
determining when a predetermining time period after turbine shutdown has elapsed; and
turning the auxiliary motor off after the time period has elapsed if the auxiliary motor is on at that time.
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Abstract
The present invention relates to a device for extending the performance life of a gas turbine engine by rotating the turbine after shutdown to achieve uniform cooling. The apparatus includes a motor, a high ratio gearset engaged with the motor, an overridable coupling means engaging the gearset with an accessory shaft of the turbine, and a logic circuit. The circuit determines when the engine has been shut down and continues to rotate the turbine for a predetermined period of time. If an external force interferes with the post-shutdown turning, the circuit will sense that force and compensate for it.
67 Citations
13 Claims
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1. A method of uniformly cooling a gas turbine engine having a spool, comprising the steps of:
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determining when the engine is shutdown; turning on an auxiliary motor to rotate the spool after the engine is shutdown; determining if an external force in preventing the auxiliary motor form rotating the spool; turning off the auxiliary motor if such an external force is detected and allowing the external force to rotate the spool; determining when a predetermining time period after turbine shutdown has elapsed; and
turning the auxiliary motor off after the time period has elapsed if the auxiliary motor is on at that time. - View Dependent Claims (2, 3)
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4. A method of uniformly cooling a gas turbine engine having a spool, comprising the steps of:
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determining when the engine is shutdown; rotating the spool after the engine is shutdown by means of an auxiliary motor; determining when a predetermined time period after turbine shutdown has elapsed; ceasing rotation of the spool after the predetermined time period has elapsed; monitoring the engine to determine of an external force is preventing the auxiliary motor from rotating the spool during the predetermined time period; and turning off the auxiliary motor if such an external force is detected and allowing the external force to rotate the spool. - View Dependent Claims (5, 6, 7)
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8. A method of uniformly cooling a gas turbine engine, comprising the steps of:
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monitoring the speed of the engine to determine if the engine speed has exceeded a first predetermined speed and then subsequently slowed below a second predetermined speed; activating an auxiliary motor to continue rotating the engine when the engine speed has slowed below the second predetermined speed after previously exceeding the first predetermined speed; and deactivating the auxiliary motor after a predetermined period of time after the activation of the auxiliary motor. - View Dependent Claims (9, 10, 11, 12, 13)
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Specification