Gas turbine engine with intercooling turbine section

1. A gas turbine engine comprising:

a combustor section;

a fan section along an engine axis forward of said combustor section;

a low pressure turbine section along said engine axis aft of said combustor section; and

an intercooling turbine section along said engine axis aft of said fan section and forward of said combustor section, said intercooling turbine section including an upstream intercooling turbine variable vane, an intercooling turbine rotor, and a downstream intercooling turbine variable vane, and

wherein said intercooling turbine section is situated in an intermediate flow path that is inboard of an outer bypass flow path, said intermediate flow path splitting downstream from said intercooling turbine section into a second stream bypass flow path and a core flow path, said second stream bypass flow path being inboard of said outer bypass flow path and extending to an exhaust nozzle, said exhaust nozzle being located aft of said low pressure turbine section and inboard of said outer bypass flow path.

2. The gas turbine engine as recited in claim 1 , wherein said fan section includes a bypass fan and a multistage fan.

3. The gas turbine engine as recited in claim 1 , further comprising a low pressure compressor section downstream of said intercooling turbine section.

4. The gas turbine engine as recited in claim 1 , further comprising a high pressure compressor section downstream of said intercooling turbine section and upstream of said combustor section.

5. The gas turbine engine as recited in claim 1 , further comprising a high pressure turbine section downstream of said combustor section and upstream of said low pressure turbine section.

6. The gas turbine engine as recited in claim 1 , wherein said downstream intercooling turbine variable vane is immediately upstream of said split in said intermediate flow path between said second stream bypass flow path and said core flow path.

7. The gas turbine engine as recited in claim 6 , wherein said combustor section is in communication with said core flow path.

8. The gas turbine engine as recited in claim 6 , further comprising a high pressure compressor section and a high pressure turbine section in communication with said core flow path.

9. The gas turbine engine as recited in claim 8 , further comprising a low pressure compressor section downstream of said intercooling turbine section in communication with said core flow path.

10. The gas turbine engine as recited in claim 9 , further comprising an inlet guide vane upstream of said low pressure compressor section and downstream of said intercooling turbine section, said inlet guide vane within said core flow path.

11. The gas turbine engine as recited in claim 1 , wherein said upstream intercooling turbine variable vane and said downstream upstream intercooling turbine variable vane are configured to modulate intercooling turbine expansion pressure ratio responsive to first and second flight conditions.

12. A gas turbine engine comprising:

a combustor section;

a low spool along an engine axis with a fan section and an intercooling turbine section forward of said combustor section; and

a high spool along said engine axis with a high pressure compressor section and a high pressure turbine section, said high pressure compressor section forward of said combustor section and said high pressure turbine section aft of said combustor section, and

wherein said intercooling turbine section includes upstream and downstream intercooling turbine variable vanes configured to modulate intercooling turbine expansion pressure ratio responsive to first and second flight conditions.

13. The gas turbine engine as recited in claim 12 , wherein low spool includes a low pressure compressor section aft of said intercooling turbine section and forward of said combustor section.

14. The gas turbine engine as recited in claim 12 , wherein low spool includes a low pressure turbine section aft of said combustor section.

15. The gas turbine engine as recited in claim 12 , wherein said fan section includes a bypass fan and a multistage fan, said bypass fan driven by said low spool through a geared architecture.

16. The gas turbine engine as recited in claim 15 , wherein said bypass fan communicates with a bypass flow path generally defined by the outer case structure and an intermediate case structure, a second stream bypass flowpath generally defined by said intermediate case structure and an inner case structure, a core flow path defined by said inner case structure such that said second stream bypass flow path is radially inward of said bypass flow path and said core flow path is radially inward of said bypass flowpath.

17. The gas turbine engine as recited in claim 12 , wherein said first flight condition is a takeoff flight condition and said second flight condition is a cruise flight condition.

18. The gas turbine engine as recited in claim 12 , wherein said intercooling turbine section is situated in an intermediate flow path that is inboard of an outer bypass flow path, said intermediate flow path splitting downstream from said intercooling turbine section into a second stream bypass flow path and a core flow path, said second stream bypass flow path being inboard of said outer bypass flow path and extending to an exhaust nozzle, said exhaust nozzle being located aft of said high pressure turbine section and inboard of said outer bypass flow path.

19. A method of operating a gas turbine engine comprising:

modulating a guide vane of an intercooling turbine section forward of a combustor section to reduce the intercooling turbine expansion pressure ratio (ICT PR) during a first flight condition by closing an upstream intercooling turbine variable vane and opening a downstream intercooling turbine variable vane; and

modulating the guide vane of the intercooling turbine section to increase the intercooling turbine expansion pressure ratio (ICT PR) during a second flight condition by opening the upstream intercooling turbine variable vane and closing the downstream intercooling turbine variable vane.

20. The method as recited in claim 19 , wherein the first flight condition is a takeoff flight condition.

21. The method as recited in claim 19 , wherein the second flight condition is a cruise flight condition.

22. The method as recited in claim 19 , wherein modulating the guide vane includes moving the guide vane between a 5%-25% closed position.