Gas turbine engine with differing effective perceived noise levels at differing reference points and methods for operating gas turbine engine
AssigneeROLLS-ROYCE plc
InventorsAlastair D Moore, Robert J Telling
Life of this patent
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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 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.
Claims30
A gas turbine engine for an aircraft, the 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;
- and
- a gearbox that receives an 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 arranged such that, during a noise certification test of an aircraft to which the gas turbine engine is attached,
- contribution of the turbine to Effective Perceived Noise Level (EPNL) at a take-off lateral reference point is in a range of from 7 EPNdB to 30 EPNdB lower than contribution of the turbine to the EPNL at an approach reference noise measurement point.
A method of performing a noise certification test of an aircraft comprising a gas turbine engine that comprises:
- 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;
- and
- a gearbox that receives an 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,
- the method comprising:
- performing a first test at a take-off lateral reference point;
- and
- performing a second test at an approach reference noise measurement point,
- wherein contribution of the turbine to Effective Perceived Noise Level (EPNL) at the take-off lateral reference point is in a range of from 7 EPNdB to 30 EPNdB lower than contribution of the turbine to the EPNL at the approach reference noise measurement point.
A method of operating an aircraft comprising a gas turbine engine that comprises:
- 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;
- and
- a gearbox that receives an 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,
- the method comprising:
- taking off from a runway and landing on a runway with the aircraft so that contribution of the turbine to Effective Perceived Noise Level (EPNL) at a take-off lateral reference point, defined as a point on a line parallel to and 450 m from a runway centre line where the EPNL is a maximum during the take-off, is in a range of from 7 EPNdB to 30 EPNdB lower than contribution of the turbine to the EPNL at a point on the ground that is 120 m directly below a path of the aircraft during the landing.
A method of operating a gas turbine engine attached to 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;
- and
- a gearbox that receives an 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,
- the method comprising:
- using the gas turbine engine to provide thrust to the aircraft for taking off from a runway and landing on a runway so that contribution of the turbine to Effective Perceived Noise Level (EPNL) at a take-off lateral reference point, defined as a point on a line parallel to and 450 m from a runway centre line where the EPNL is a maximum during the take-off, is in a range of from 7 EPNdB to 30 EPNdB lower than contribution of the turbine to the EPNL at a point on the ground that is 120 m directly below a path of the aircraft during the landing.
Dependencies are inferred from the claim text.