Gas turbine engine case counterflow thermal control

Abstract

A thermal control apparatus is provided for gas turbine engine cases and particularly for thermal control of clearances between turbine rotors and surrounding shrouds. Thermal control of an annular case section or ring is provided by counterflowing two heat transfer fluid flowpaths in heat transfer communication with the section of engine casing. The flowpaths may be in parallel or series such that there is substantially no circumferential gradient in the mass flowrate weighted average temperature of the heat transfer fluid supplied by the two counterflowing fluid flowpaths. One embodiment provides forward and aft rings cooled by three spray tubes in each of two 180.degree. sectors whereby the forward and aft spray tubes flow thermal control air flowing in one circumferential direction and the middle spray tubes flows thermal control air in an opposite circumferential direction.

Dependencies are inferred from the claim text.