Rolls-royce Corporation

Nigel H S Smith

Mark J Wilson

Benedict R Phelps

Gabriel Gonzalez-Gutierrez

Marco Barale

Kashmir S Johal

Craig W Bemment

Stephane M M Baralon

Peter J G Schwaller

A gas turbine engineis provided in a fan root to tip pressure ratio, defined as the ratio of the mean total pressure of the flow at the fan exit that subsequently flows through the engine core (P) to the mean total pressure of the flow at the fan exit that subsequently flows through the bypass duct (P), is no greater than a certain value. The gas turbine enginemay provide improved efficiency when compared with conventional engines, whilst retaining an acceptable flutter margin.

Pressure ratio distributions for a gas turbine engine

A gas turbine engineis provided in which a fan having fan blades in which the camber distribution along the span allows the gas turbine engine to operate with improved efficiency when compared with conventional engines, whilst retaining an acceptable flutter margin.

Gas turbine engine

A fan blade is provided with an aerofoil portion for which, for cross-sections through the aerofoil portion at radii between 15% and 25% of the blade span from the root radius, the average leading edge thickness is greater than the leading edge thickness at the tip. The geometry of the fan blade may result in a lower susceptibility to flutter.

Gas turbine engine fan blade

A fan blade is provided with an aerofoil portion for which, at radii between 20% and 40% of the blade span, the location of the position of maximum thickness along the camber line is at less than a defined percentage of the total length of the camber line. For all cross-sections through the aerofoil portion at radii greater than 70% of the blade span, the location of the position of maximum thickness along the camber line is at more than a defined percentage of the total length of the camber line. The geometry of the fan blade may result in a lower susceptibility to flutter.

Noise control with respect to rotating machinery such as gas turbine engines is important to meet acceptable operational and environmental constraints. Buzz-saw noise in particular is due to differences in blade to blade geometries both as assembled and due to blade manufacturing tolerance variations. Generally, a plurality of blades rotate within a duct and some noise propagates forwards of the blade assembly. In order to abate such noise an acoustic lining is provided. By consideration of the acoustic attenuation effects of that lining, it is possible to rearrange the blades within the blade assembly such that the overall noise attenuation effects are improved. Thus, the blade assembly may be rearranged such that there is a reduction in the Fourier coefficients at harmonics above and below the harmonics most attenuated by the acoustic attenuation treatment or lining or alternatively the effect of that lining maximized by rearrangement of the blades to shift the harmonics to those most attenuated by the acoustic treatment.

Growing community of inventors

Derby, United Kingdom

Nigel H S Smith