Methods and systems for a modulated bleed valve

1. A gas turbine engine, comprising:

a turbine section comprising alternating rows of rotary airfoils and static vanes, the turbine section including a high pressure turbine;

a combustor;

a turbine nozzle coupled to the combustor and disposed forward of the high pressure turbine, the turbine nozzle comprising a nozzle choke area; and

a modulated bleed valve in communication with a controller, wherein:

the modulated bleed valve disposed aft of the nozzle choke area;

the modulated bleed valve is configured to assume, in response to a command by the controller, at least one of an open configuration, a closed configuration, or a partially open configuration ranging between the open configuration and the closed configuration, and when in at least one of the open configuration or the partially open configuration, the modulated bleed valve allows a bleed airflow through the turbine nozzle aft of the nozzle choke area and reroutes the bleed airflow forward to join a nozzle airflow at a point aft of the nozzle choke area and forward of the high pressure turbine; and the bleed airflow is configured to cool the turbine nozzle and rotate the high pressure turbine.

2. The gas turbine engine of claim 1 , wherein the modulated bleed valve comprises a valve actuator configured to move the modulated bleed valve into at least one of the open configuration, the partially open configuration, or the closed configuration in response to the command by the controller.

3. The gas turbine engine of claim 1 , wherein the modulated bleed valve, when in at least one of the open configuration or the partially open configuration, increases the nozzle airflow by 3% to 5% by adding the bleed airflow.

4. The gas turbine engine of claim 3 , wherein a high pressure compressor surge margin increases by greater than 5% from a baseline value.

5. The gas turbine engine of claim 1 , further comprising a tangible, non-transitory memory configured to communicate with the controller, the tangible, non-transitory memory having instructions stored thereon that, in response to execution by the controller, cause the controller to perform operations, comprising:

receiving, by the controller, a first plurality of parameter values from a plurality of parameter sensors under which the gas turbine engine is commanded to operate at a first time;

determining, by the controller, a first desired bleed airflow to flow through the modulated bleed valve in response to the first plurality of parameter values;

commanding, by the controller, the modulated bleed valve to assume at least one of the open configuration, the partially open configuration ranging between the open configuration and the closed configuration, or the closed configuration in response to the determining the first desired bleed airflow.

6. A method of varying bleed airflow in a gas turbine engine, comprising:

receiving, by a controller, a first plurality of parameter values from a plurality of parameter sensors under which the gas turbine engine is commanded to operate at a first time;

determining, by the controller, a first desired bleed airflow through a modulated bleed valve in response to the first plurality of parameter values;

commanding, by the controller, the modulated bleed valve to assume at least one of an open configuration, a closed configuration, or a first partially open configuration ranging between the open configuration and the closed configuration in response to the first desired bleed airflow, wherein, when in at least one of the open configuration or the first partially open configuration, the modulated bleed valve reroutes a bleed airflow forward of the modulated bleed valve to join a nozzle airflow aft of a nozzle choke area and forward of a high pressure turbine, the modulated bleed valve being disposed aft of the nozzle choke area; and

wherein the bleed airflow is used to cool a turbine nozzle and rotate the high pressure turbine.

7. The method of claim 6 , further comprising moving, by a valve actuator, the modulated bleed valve into at least one of the open configuration, the first partially open configuration, or the closed configuration.

8. An article of manufacture including a tangible, non-transitory computer-readable storage medium configured to communicate with a controller, the tangible, non-transitory computer-readable medium having instructions stored thereon that, in response to execution by the controller, cause the controller to perform operations, comprising:

receiving, by the controller, a first plurality of parameter values from a plurality of parameter sensors under which a gas turbine engine is commanded to operate at a first time;

determining, by the controller, a first desired bleed airflow through a modulated bleed valve in response to the first plurality of parameter values;

commanding, by the controller, the modulated bleed valve to assume at least one of an open configuration, or a closed configuration, a first partially open configuration ranging between the open configuration and the closed configuration in response to the first desired bleed airflow, wherein, when in at least one of the open configuration or the first partially open configuration, the modulated bleed valve reroutes a bleed airflow forward of the modulated bleed valve to join a nozzle airflow aft of a nozzle choke area and forward of a high pressure turbine, the modulated bleed valve being disposed aft of the nozzle choke area; and

wherein the bleed airflow is used to cool a turbine nozzle and rotate the high pressure turbine.