Abstract: A heat pipe, which may for instance be in the form of an aerofoil blade for a gas turbine engine, is provided with capillary means which is in two different forms. One form is constituted by a porous material and the other constituted by grooves formed in the surface of the internal wall of the heat pipe.

Abstract: A gas turbine engine has a turbine which includes an annular array of rotary aerofoil blades surrounded by an annular shroud member. All or a major portion of the annular shroud member is constituted by a heat pipe. A distance measuring device is provided to measure the clearance between the tips of the rotary aerofoil blades and the shroud member and its output is monitored by a control unit. The control unit is adapted to control a valve which regulates the flow rate of cooling air directed onto the heat pipe. The arrangement is such that the temperature of the heat pipe is maintained at a level which is consistent with the clearance between the rotary aerofoil blade tips and the annular shroud member being within a predetermined range of values.

Abstract: An aerofoil blade for a gas turbine engine is in the form of a heat pipe. The aerofoil blade has an internal passageway adapted to contain a secondary structure and to thermally insulate that secondary structure from the remainder of the aerofoil blade by, for instance, the provision of a cooling air passage between the internal passageway and secondary structure.

Abstract: A stator aerofoil blade for a gas turbine engine is manufactured in the form of a heat pipe so that during engine operation, the blade remains substantially isothermal. Localized thermal gradients within the blade are minimized thereby reducing the possibility of blade distortion or cracking.A shroud ring for a gas turbine engine is manufactured in the form of a heat pipe so that during engine operation, the ring remains substantially isothermal. Localized thermal gradients within the ring are minimized, thereby reducing the possibility of ring distortion occurring.