Disclosed herein is a method of automatically determining an operating condition of at least part of a gas turbine engine 10 for an aircraft, the method comprising: measuring one or more gas pressure waves by a gas pressure detector 401, wherein the gas pressure detector 401 is located in the gas turbine engine 10; and automatically determining, by a computing system, an operating condition of at least part of a gas turbine engine 10 in dependence on an output signal of the gas pressure detector 401.

A method of designing a gas turbine engine comprises the steps of including a fan section with a fan. A turbine section is included having a first turbine and a high pressure turbine. A gear reduction is included between the fan and the first turbine, the gear reduction being configured to receive an input from the first turbine and to turn the fan at a lower speed than the first turbine in operation. The first turbine is designed to include a number of turbine blades in each of a plurality of rows of the first turbine, the first turbine blades operating at least some of the time at a rotational speed, and the number of blades and the rotational speed being such that the following formula holds true for at least one of the blade rows of the first turbine: (number of bladesspeed)/605500.

A system and method for meeting take off noise requirements in a gas turbine engine with a multi-stage fan, comprising an inlet passage, a core passage, a bypass passage and a mid-stage offtake passage; the core passage comprising a core inlet, high pressure compressor, combustor, high pressure turbine, low pressure turbine and a core exhaust; the bypass passage comprising a primary bypass inlet and a primary bypass exit; the mid-stage offtake passage comprising an offtake inlet and offtake exit; a first stage comprising a first rotor, and a second stage comprising a second rotor; and a variable guide vane located axially between the first rotor and the second rotor; an actuator coupled to and selectively varying the variable guide vane between two or more orientations; a variable offtake exit thrust nozzle; and, wherein a gas stream exiting the inlet passage enters one of the core, bypass or mid-stage off take passages as a function of the two or more orientations.

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 fan. The fan tip relative Mach Number at take-off 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 below 1.09. This results in low fan noise, along with optionally enabling a reduction in noise attenuation material.

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.

A method for actively damping oscillations in a compression process, the method being performed by a controller. The method includes acquiring process data from a compression process, performing oscillation frequency estimation of any detected oscillations in the process data, generating a damping signal based on the oscillation frequency estimation, and providing the damping signal to an electrical drive of the compression process.

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.

A gas turbine engine includes a fan and an engine core that includes a compressor, a combustor, and a turbine. The fan and the compressor include variable pitch geometry. The gas turbine engine further includes a control system configured to adjust the variable pitch geometry of the fan and the compressor to optimize a performance characteristic of 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 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.

An electric machine coupled to rotating machinery includes a rotor and a stator, and the method of control of an electric machine and an electric machine control system. The method includes sensing one or more parameters indicative of one or more resonance conditions of the rotating machinery, and comparing the sensed parameter to a predetermined threshold to determine whether the rotating machinery is operating at the resonance condition. Where the rotating machinery is determined to be operating at the resonance condition, adjusting a magnetic field of one or both of the rotor and the stator to provide a predetermined torque to the rotating machine, to modulate the stiffness of the rotational machinery, and thereby move the resonance condition away from the current rotating machinery conditions.