Abstract: An axial flow gas turbine is provided with a shroud ring which is defined by two axially adjacent heat pipes. The radially inner face of the shroud ring has a plurality of axially extending cooling air passages located adjacent to it. Cooling air, which in operation is directed through the passages serves to provide cooling of the shroud ring and the substantial elimination of any radial heat flux in the shroud ring.

Abstract: A gas turbine engine is provided with an annular array of rotor blades which are surrounded by a shroud ring. The shroud ring includes a number of adjacent heat pipes which are of the variable conductance type. The heat pipes each have a portion which is externally of the shroud ring which portion is in turn divided into two parts. The first part is exposed to a flow of cooling air while the second part contains a buffer which operationally varies the conductance of the heat pipe, in accordance with the temperature of air which is tapped from the high pressure compressor of the engine. This serves to ensure that the shroud ring remains substantially isothermal and provides control over the clearance between the tips of the rotary blades and the shroud ring through thermal control of the shroud ring.