Compartment cooling for a gas turbine engine
A gas turbine engine includes a first pump driven by a spool, an air-oil cooler downstream of the first pump. A second pump driven by the spool and an air-air precooler downstream of the second pump, the air-air precooler downstream of the air-oil cooler. A compartment is downstream of the precooler to receive a cooling air from the precooler.
1. A gas turbine engine comprising:
a spool;
a first pump driven by said spool;
an air-oil cooler downstream of said first pump;
a second pump driven by said spool, wherein said first pump and said second pump are driven by said spool through a constant speed transmission;
an air-air precooler downstream of said second pump, said air-air precooler downstream of said air-oil cooler; and
a compartment downstream of said precooler to receive a cooling air from said air-air precooler.
2. The gas turbine engine as recited in claim 1 , wherein said compartment is a bearing compartment.
3. The gas turbine engine as recited in claim 1 , wherein said compartment is adjacent to a turbine section.
4. The gas turbine engine as recited in claim 1 , wherein said cooling air is at approximately 50 psi.
5. The gas turbine engine as recited in claim 1 , wherein said cooling air is less than 450 F.
6. The gas turbine engine as recited in claim 1 , wherein said spool is a low spool.
7. The gas turbine engine as recited in claim 1 , wherein said precooler ejects a hot air into an annular bypass flow path to provide thrust recovery.
8. The gas turbine engine as recited in claim 1 , wherein said constant speed transmission is driven by a towershaft geared to said spool.
9. The gas turbine engine as recited in claim 1 , wherein said spool operates at speed excursions of up to 80% between a first operating condition and a second operating condition.
10. The gas turbine engine as recited in claim 1 , wherein said spool drives a fan through a geared architecture.
11. The gas turbine engine as recited in claim 1 , wherein said compartment is within a mid-turbine frame.
12. The gas turbine engine as recited in claim 11 , wherein said cooling air is communicated through tubing external to an engine case to said compartment.
13. The gas turbine engine as recited in claim 1 , wherein said first pump and said second pump are in fluid communication with an annular fan bypass.
14. The gas turbine engine as recited in claim 13 , wherein said air-air precooler exhausts into said annular fan bypass to provide thrust recovery.
15. A method of thermal control for a gas turbine engine comprising:
selectively communicating either a fan bypass flow from an annular bypass flow path or a bleed flow from a low pressure compressor to an Air-Oil Cooler and an Air-Air PreCooler, the Air-Air PreCooler immediately downstream of the Air-Oil Cooler, wherein the Air-Oil Cooler is downstream of a first pump and the Air-Air PreCooler is downstream of a second pump and the first pump and the second pump are driven by a spool through a constant speed transmission; and
communicating a cooling air from the Air-Air Precooler to a compartment downstream of the Air-Air Precooler.
16. The method as recited in claim 15 , further comprising pumping from the fan bypass flow.
17. The method as recited in claim 15 , further comprising pumping the bleed flow.
18. The method as recited in claim 15 , further comprising communicating the cooling air through tubing external to an engine case.
19. The method as recited in claim 15 , further comprising exhausting the air-air precooler into the annular bypass flow path to provide thrust recovery.