Rolls-royce Corporation

Rolls-royce Deutschland Ltd & Co. Kg

Alastair D Moore

Robert J Telling

Richard Geoffrey Stretton

Marco Rose

Fredi Holste

Frank Arnold

A gas turbine engine generates noise during use, and one particularly important flight condition for noise generation is take-off. A gas turbine engine that has high efficiency provides low noise, in particular from the fan and the turbine that drives the fan. Values are defined for a noise parameter NP that results in a gas turbine engine having reduced combined fan and turbine noise.

Geared gas turbine engine

A gas turbine engine generates noise during use, and one particularly important flight condition for noise generation is take-off. A gas turbine engine is provided that has high efficiency together with low noise, in particular from the jet flow exiting the engine and the turbine. The combined contribution of the jet and the turbine to the Effective Perceived Noise Level (EPNL) at a take-off lateral reference point, defined as the point on a line parallel to and 450 m from the runway centre line where the EPNL is a maximum during take-off, is in the range of from 3 EPNdB and 15 EPNdB lower than the total engine EPNL at the take-off lateral reference point.

Low noise gas turbine engine

A gas turbine engine generates noise during use, and one particularly important flight condition for noise generation is take-off. A gas turbine engine has high efficiency together with low noise, in particular from the bypass flow exiting the engine. The average velocity of the flow at the exit to the bypass duct is in the range of from 200 m/s to 275 m/s at a take-off lateral reference point, defined as the point on a line parallel to and 450 m from the runway centre line where the Effective Perceived Noise Level (EPNL) is a maximum during take-off.

Gas turbine engine with fan, bypass duct, and gearbox and method of operating the gas turbine engine

A gas turbine engine generates noise during use, and one particularly important flight condition for noise generation is take-off. A gas turbine engine has high efficiency together with low noise, in particular the noise emanating from the front of the fan. The contribution of the fan noise emanating from the front of the engine to the Effective Perceived Noise Level (EPNL) at a take-off lateral reference point, defined as the point on a line parallel to and 450 m from the runway centre line where the EPNL is a maximum during take-off, is in the range of from 0 EPNdB and 12 EPNdB lower than the contribution of the fan noise emanating from the rear of the engine to the EPNL at the take-off lateral reference point.

Gas turbine engine

A gas turbine engine generates noise during use, and one particularly important flight condition for noise generation is take-off. A gas turbine engine has high efficiency together with low noise, in particular from the turbine that drives the fan. The contribution of the turbine noise emanating from the rear of the engine to the Effective Perceived Noise Level (EPNL) is in the range of from 7 EPNdB and 30 EPNdB lower at a take-off lateral reference point than at an approach reference point.

Gas turbine engine with differing effective perceived noise levels at differing reference points and methods for operating gas turbine engine

A device for simulating sound produced by certain equipment, for example a rotor-stator arrangement of a turbomachine, or for generation of opposing sound fields for active sound control, including active sound reduction and active sound amplification, comprises flow obstacles () provided in a flow duct () flown by a fluid at which vortices () are shed at a certain frequency depending on the shape and size of the flow obstacles and the velocity of flow. The quantity and spatial arrangement of the flow obstacles is selected such that a periodically spatially and temporally changing pressure field for the excitation of a sound field () of a certain modal content is produced by the entirety of the vortices shed. This sound field reacts synchronizingly on the vortex shedding. The resonant circuit so formed, whose vortex shedding frequency is in the range of the resonant frequency of the sound field to be excited, is the sound source.

Arrangement for the generation of sonic fields of a specific modal composition

An aircraft comprising an aeroengine and a noise reflective surface, the aeroengine capable of generating a hot exhaust jet and noise characterized in that the reflective surface is profiled to reflect noise from the aeroengine into the hot exhaust jet thereby attenuating reflected noise.

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Derby, United Kingdom

Alastair D Moore