Injection cooled cooling air system for a gas turbine engine

1. A gas turbine engine comprising:

an engine core having a compressor section, a combustor section fluidly connected to the compressor section, and a turbine section fluidly connected to the combustor section;

at least one compressor bleed connecting a compressor flowpath with a first cooled cooling air path, the at least one compressor bleed including a first compressor bleed disposed at a compressor outlet;

the first cooled cooling air path including a supplementary coolant injector connected to a supplementary coolant supply and configured to inject a supplementary coolant into the first cooled cooling air path, the first cooled cooling air path including a portion exterior to the engine core,

wherein the first cooled cooling air path ducts bleed air to an input port at, or near, a last stage of the compressor section; and

the supplementary coolant contained in said supplementary coolant supply comprises at least one of liquid nitrogen, liquid CO2 and liquid air.

2. The gas turbine engine of claim 1 , wherein the supplementary coolant injector is exterior to the engine core.

3. The gas turbine engine of claim 1 , wherein at least a second compressor bleed of the at least one compressor bleed is disposed at a mid-compressor stage.

4. The gas turbine engine of claim 1 , wherein the supplementary coolant is configured to cool coolant in said first cooled cooling air path at least partially via expansion of the supplementary coolant.

5. The gas turbine engine of claim 1 , wherein the supplementary coolant injector comprises a plurality of supplementary coolant ports, each supplementary coolant port in said plurality of supplementary coolant ports being configured to inject a portion of the supplementary coolant into the first cooled cooling air path.

6. The gas turbine engine of claim 1 , wherein the at least one compressor bleed comprises at least the first compressor bleed connected to the first cooled cooling air path and a second compressor bleed connected to a second cooled cooling air path, and wherein the supplementary coolant connected to the first cooled cooling air path is a liquid, and a second supplementary coolant connected to the second cooled cooling air path is a compressed gas.

7. The gas turbine engine of claim 6 , wherein the supplementary coolant is configured to cool coolant in said first cooled cooling air path at least partially via a state change of the supplementary coolant.

8. The gas turbine engine of claim 1 , further comprising an engine controller controllably coupled to said supplementary coolant injector and configured to control injection of the supplementary coolant in the supplementary coolant supply through the supplementary coolant injector.

9. The gas turbine engine of claim 8 , wherein the controller includes a memory storing instructions configured to cause the controller to operate the supplementary coolant injector at a first injection level during a first mode of engine operations, and at a second injection level during a second mode of engine operations.

10. The gas turbine engine of claim 1 , wherein the first cooled cooling air path includes a heat exchanger configured to cool bleed air passing through the first cooled cooling air path.

11. The gas turbine engine of claim 1 , wherein the supplementary coolant supply is distinct from the compressor.

12. The gas turbine engine of claim 1 , wherein the supplementary coolant supply is a supplementary coolant reservoir.

13. The gas turbine engine of claim 1 , wherein the supplementary coolant supply includes a first supplementary coolant reservoir and a second supplementary coolant reservoir distinct from the first supplementary coolant reservoir.

14. The gas turbine engine of claim 13 , wherein a first coolant contained in the first supplementary coolant reservoir is a distinct coolant from a second coolant contained in the second supplementary coolant reservoir.