INTERCOOLED COOLING AIR USING EXISTING HEAT EXCHANGER

1 . A gas turbine engine comprising;

a main compressor section having a high pressure compressor with a downstream discharge, and upstream locations;

a turbine section having a high pressure turbine;

a tap tapping air from at least one of the more upstream locations in the main compressor section, the tap passing the tapped air through a heat exchanger and then to a cooling compressor compressing air downstream of the heat exchanger, the cooling compressor delivering compressed air into the turbine section; and

an accessory gear box driving the cooling compressor.

2 . The gas turbine engine as set forth in claim 1 , a tower shaft driven by the main compressor section, the tower shaft driving the accessory gearbox.

3 . The gas turbine engine as set forth in claim 2 , wherein the tower shaft is driven by the high pressure compressor section.

4 . The gas turbine engine as set forth in claim 1 , wherein the accessory gearbox drives at least one component different than the cooling compressor.

5 . The gas turbine engine as set forth in claim 4 , wherein the at least one component different than the cooling compressor comprises one of a fuel pump, oil pump and generator.

6 . The gas turbine engine as set forth in claim 4 , wherein the accessory gearbox includes pads defining mounting locations for accessory components and the cooling compressor is mounted to one of the pads of the accessory gearbox.

7 . The gas turbine engine as set forth in claim 2 , wherein the cooling compressor includes a centrifugal compressor impeller.

8 . The gas turbine engine as set forth in claim 7 , wherein the accessory gearbox includes a gear ratio such that the impeller of the cooling compressor rotates at a speed different than the tower shaft.

9 . The gas turbine engine as set forth in claim 1 , wherein an air temperature at the downstream discharge of the high pressure compressor is greater than or equal to about 1350° F.

10 . The gas turbine engine as set forth in claim 1 , wherein cooling air output from the cooling compressor is delivered into the high pressure turbine.

11 . The gas turbine engine as set forth in claim 1 , wherein the tap comprises an outlet from the high pressure compressor through which airflow is directed to the heat exchanger.

12 . The gas turbine engine as set forth in claim 1 , including a main fan delivering bypass air into a bypass duct and into the main compressor section with the heat exchanger positioned within the bypass duct for cooling air tapped from the main compressor section.

13 . An intercooling system for a gas turbine engine comprising:

a heat exchanger for cooling air drawn from a portion of a main compressor section at a first temperature and pressure for cooling the air to a second temperature cooler than the first temperature;

a cooling compressor compressing air communicated from the heat exchanger to a second pressure greater than the first pressure and communicating the compressed air to a portion of a turbine section; and

the cooling compressor mounted to an accessory gearbox.

14 . The intercooling system as set forth in claim 13 , including a tower shaft driven by the main compressor section, the tower shaft driving the accessory gearbox.

15 . The intercooling system as set forth in claim 14 , wherein the accessory gearbox drives at least one component different than cooling compressor.

16 . The intercooling system as set forth in claim 14 , wherein the cooling compressor includes a centrifugal compressor impeller.

17 . The intercooling system as set forth in claim 16 , wherein the accessory gearbox includes a gear ratio such that the impeller of the cooling compressor rotates at a speed different than the tower shaft.

18 . A gas turbine engine comprising;

a main compressor section having a high pressure compressor with a downstream discharge, and more upstream locations, a low pressure compressor providing some of said more upstream locations;

a turbine section having at least two turbine rotors, with a first being at a higher pressure than a second; and

a tap tapping air from at least one of said more upstream locations in said compressor section, passing said tapped air through a heat exchanger and then to a cooling compressor, said cooling compressor compressing air downstream of said heat exchanger, and delivering air to said first turbine rotor; and

an accessory gearbox with a plurality of mounting locations for accessory components, wherein the cooling compressor is mounted to one of the plurality of mounting locations.