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US 12,692,823 B2Granted
Geared gas turbine engine with improved noise signature
AssigneeROLLS-ROYCE plc
InventorsAlastair D Moore, Robert J Telling
Life of this patent
Estimating the term…
Abstract
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 fan and the turbine that drives the fan. Values are defined for a combined contribution of the turbine noise and the noise from the fan emanating from the front of the engine to the Effective Perceived Noise Level (EPNL) at take-off to be in the range of from 2 EPNdB and 15 EPNdB lower than the EPNL of the whole engine at take-off.
Claims16
A gas turbine engine for an aircraft, the gas turbine engine comprising:
- an engine core comprising a turbine, a compressor, and a core shaft connecting the turbine to the compressor;
- a fan located upstream of the engine core, the fan comprising a plurality of fan blades;
- a bypass duct defined between an inner flow boundary formed by the engine core and an outer flow boundary formed by a nacelle;
- and
- a gearbox that receives input from the core shaft and outputs drive to the fan so as to drive the fan at a lower rotational speed than the core shaft, wherein:
- the gas turbine engine is configured such that, during a noise certification test of the aircraft, which is taking off from a runway and to which the gas turbine engine is attached, a combined contribution of (i) noise from the turbine and (ii) noise from the fan emanating from a front of the engine to a whole Effective Perceived Noise Level (EPNL) of the gas turbine engine at a take-off lateral reference point, defined as a point on a line parallel to and 450 m from a center line of the runway where the EPNL is a maximum during the take-off of the aircraft, is in a range of from 2 EPNdB and 15 EPNdB lower than the whole EPNL at the take-off lateral reference point;
- a bypass noise attenuation proportion L is defined as:
- L
- =
- J
- +
- H
- 2
-
- G
- where:
- G is an axial length between tips of trailing edges of the fan blades and a trailing edge of the nacelle;
- H is a total axial length of acoustic attenuation material provided to the outer flow boundary of the bypass duct over an axial extent between the tips of the trailing edges of the fan blades and the trailing edge of the nacelle;
- and
- J is a total axial length of acoustic attenuation material provided to the inner flow boundary of the bypass duct over the axial extent between the tips of the trailing edges of the fan blades and the trailing edge of the nacelle;
- an intake noise attenuation proportion K is defined as:
- K
- =
- E
- F
- where:
- E is a total axial length of acoustic attenuation material provided to an intake of the engine;
- and
- F is an axial length of the intake;
- a forward to rearward noise attenuation proportion M is in a range of from 0.8 to 2.5, where:
- M
- =
- K
- L
- ;
- the intake noise attenuation proportion K is in a range of from 0.55 to 0.95;
- a ratio of H/G is in a range of from 0.4 to 0.7;
- and
- a ratio of J/G is in a range of from 0.4 to 0.7.
36 more elements
A method of operating an aircraft comprising a gas turbine engine, the gas turbine engine comprising:
- an engine core comprising a turbine, a compressor, and a core shaft connecting the turbine to the compressor;
- a fan located upstream of the engine core, the fan comprising a plurality of fan blades;
- a bypass duct defined between an inner flow boundary formed by the engine core and an outer flow boundary formed by a nacelle;
- and
- a gearbox that receives input from the core shaft and outputs drive to the fan so as to drive the fan at a lower rotational speed than the core shaft, and the method comprising taking off from a runway during a noise certification test of the aircraft such that a combined contribution of (i) noise from the turbine and (ii) noise from the fan emanating from a front of the engine to a whole Effective Perceived Noise Level (EPNL) of the gas turbine engine at a take-off lateral reference point, defined as a point on a line parallel to and 450 m from a center line of the runway where the EPNL is a maximum during the take-off of the aircraft, is in a range of from 2 EPNdB and 15 EPNdB lower than the whole EPNL at the take-off lateral reference point, wherein:
- a bypass noise attenuation proportion L is defined as:
- L
- =
- J
- +
- H
- 2
-
- G
- where:
- G is an axial length between tips of trailing edges of the fan blades and a trailing edge of the nacelle;
- H is a total axial length of acoustic attenuation material provided to the outer flow boundary of the bypass duct over an axial extent between the tips of the trailing edges of the fan blades and the trailing edge of the nacelle;
- and
- J is a total axial length of acoustic attenuation material provided to the inner flow boundary of the bypass duct over the axial extent between the tips of the trailing edges of the fan blades and the trailing edge of the nacelle;
- an intake noise attenuation proportion K is defined as:
- K
- =
- E
- F
- where:
- E is a total axial length of acoustic attenuation material provided to an intake of the engine;
- and
- F is an axial length of the intake;
- a forward to rearward noise attenuation proportion M is in a range of from 0.8 to 2.5, where:
- M
- =
- K
- L
- ;
- the intake noise attenuation proportion K is in a range of from 0.55 to 0.95;
- a ratio of H/G is in a range of from 0.4 to 0.7;
- and
- a ratio of J/G is in a range of from 0.4 to 0.7.
35 more elements
Dependencies are inferred from the claim text.