Rolls-Royce Corporation

Brian Barry

David W Artt

Susan M Allen

Christopher Freeman

John H Sadler

In order to combat flutter in rotor blades rotating within a duct bounded by a duct wall, the duct wall incorporates cavities tuned for resonance to a known flutter frequency. The cavities, which may comprise tubes immediately underlying a facing sheet of the duct wall, are arrayed around the circumference of the duct wall and communicate with the duct through openings in the duct wall near the tips of the blades. Flutter energy from the blades is transferred directly to the cavities by pressure waves and produces resonance in the cavities so that the flutter is damped aerodynamically. The invention is applicable to fans in turbofan engines.

Aerodynamic damping of vibrations in rotor blades

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.

Gas turbine engine

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.

Isothermal aerofoil with insulated internal passageway

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.

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Duffield, United Kingdom

Brian Barry