Abstract: A method of thermodynamic assessment of flow through a turbomachine having a compressor, comprising: receiving sensor readings from a plurality of acoustic sensors located about an intake for the turbomachine upstream of the compressor; and receiving pressure and stagnation temperature readings for the flow into the intake. A static temperature is determined for the flow into the intake and an average velocity of the flow over a flow area of the intake upstream of the compressor using the acoustic sensor readings. A mass flow rate of the flow through the intake is determined using the average velocity of the flow and the stagnation pressure.

Abstract: A turbofan gas turbine engine having a bypass duct, and a bypass airflow measurement system. The bypass airflow measurement system comprises: at least one acoustic transmitter configured to transmit an acoustic waveform across the bypass duct of the gas turbine engine though which a bypass airflow passes to at least one acoustic receiver; where the at least one acoustic transmitter and the at least one acoustic receiver are located on an axial plane that is substantially perpendicular to the bypass flow. A method of measuring bypass airflow properties of a turbofan gas turbine engine is also described.

Abstract: A flow machine having a flow passage and an air flow measurement system comprising a plurality of acoustic sensors. The acoustic sensors comprise at least one acoustic transmitter configured to transmit an acoustic waveform through the airflow passing through the flow passage to an acoustic receiver. At least one of the acoustic sensors is rotatable relative to one or more other acoustic sensor.

Abstract: A turbomachine having an air flow measurement system. The system comprises a plurality of acoustic sensors upstream of a compressor of the turbomachine. The acoustic sensors are configured to transmit acoustic waveforms through an intake airflow to further acoustic sensors. The acoustic sensors are located in a single plane and mounted at angular spacing about a central axis of an intake.

Abstract: A gas turbine engine comprises a bypass duct and a heat exchanger assembly, the heat exchanger assembly comprising a heat exchanger and a heat exchanger duct having an inlet region, an inflection region and an outlet region. A direction of a centreline of the heat exchanger duct has a tangential component with respect to a principal rotational axis of the gas turbine engine at one or more of the inlet region, the inflection region and the outlet region. The heat exchanger is disposed within the inflection region and configured to transfer heat generated by the gas turbine engine into the flow of air as it passes through the inflection region.

Abstract: A turbomachine having an air flow measurement system. The system comprises a plurality of acoustic sensors upstream a compressor of the turbomachine. The acoustic sensors comprise at least one acoustic transmitter configured to transmit an acoustic waveform through an intake airflow to an acoustic receiver. The acoustic sensors are located in a single plane and mounted at angular spacing about a central axis of an intake.

Abstract: A turbofan gas turbine engine having a bypass duct, and a bypass airflow measurement system. The bypass airflow measurement system comprises: at least one acoustic transmitter configured to transmit an acoustic waveform across the bypass duct of the gas turbine engine though which a bypass airflow passes to at least one acoustic receiver; where the at least one acoustic transmitter and the at least one acoustic receiver are located on an axial plane that is substantially perpendicular to the bypass flow. A method of measuring bypass airflow properties of a turbofan gas turbine engine is also described.

Abstract: A flow machine having a flow passage and an air flow measurement system comprising a plurality of acoustic sensors. The acoustic sensors comprise at least one acoustic transmitter configured to transmit an acoustic waveform through the airflow passing through the flow passage to an acoustic receiver. At least one of the acoustic sensors is rotatable relative to one or more other acoustic sensor.

Abstract: A method of thermodynamic assessment of flow through a turbomachine having a compressor, comprising: receiving sensor readings from a plurality of acoustic sensors located about an intake for the turbomachine upstream of the compressor; and receiving pressure and stagnation temperature readings for the flow into the intake. A static temperature is determined for the flow into the intake and an average velocity of the flow over a flow area of the intake upstream of the compressor using the acoustic sensor readings. A mass flow rate of the flow through the intake is determined using the average velocity of the flow and the stagnation pressure.

Abstract: A control system operable includes a modified primary control parameter for an aircraft, the control system includes: a primary control parameter leg configured to output a demand in an aircraft primary control parameter; a primary control parameter compensation leg configured to receive a change in absolute levels and/or spatial distributions of swirl angle and/or fan pressure at a primary control parameter relative to a reference and convert the change into the primary control parameter; a processor adapted to receive the demand in the primary control parameter output from the primary control parameter leg and the change to the primary control parameter output from the primary control parameter compensation leg; compare the demand in the primary control parameter output from the primary control parameter leg and the change to the primary control parameter output from the primary control parameter compensation leg; and generate a modified primary control parameter for the aircraft.

Abstract: A method of estimating a parameter of a fluid flowing in a passage includes: having a plurality of instruments operable to measure one or more fluid properties flowing in the passage, the plurality of instruments being disposed in the passage and arranged within a common measurement plane; assigning a stream tube to each instrument, each stream tube represents a region of space in the common measurement plane within the passage and each stream tube surrounds one of the plurality of instruments, the stream tubes together correspond to the cross-sectional shape and area of the passage in the common measurement plane; measuring the one or more fluid properties using the instruments to obtain one or more measured values for each stream tube; using the measured value(s) for each stream tube to calculate a derived value for each stream tube; and summing the derived values across all of the stream tubes.

Abstract: A flow sensor rake assembly for taking flow field measurements in flow machine, such as a compressor or turbine of gas turbine engine. Axial flow machine has rotor arranged to rotate about an axis to interact with fluid flow through the rotor in use, and static annular wall surrounding axis. Annular wall is mounted axially upstream or downstream of rotor to be washed by fluid flow in use. Flow sensor rake has elongate stem having first and second ends and plurality of probes depending therefrom at spaced locations along stem. Elongate stem is mounted to annular wall at first end and depending away from annular wall to the second end. Elongate stem is obliquely angled relative to annular wall when viewed in axial direction and second end of elongate stem is offset in circumferential direction relative to first end. Stem is slanted relative to radial direction with respect to axis.

Abstract: A method of estimating a parameter of a fluid flowing in a passage includes: having a plurality of instruments operable to measure one or more fluid properties flowing in the passage, the plurality of instruments being disposed in the passage and arranged within a common measurement plane; assigning a stream tube to each instrument, each stream tube represents a region of space in the common measurement plane within the passage and each stream tube surrounds one of the plurality of instruments, the stream tubes together correspond to the cross-sectional shape and area of the passage in the common measurement plane; measuring the one or more fluid properties using the instruments to obtain one or more measured values for each stream tube; using the measured value(s) for each stream tube to calculate a derived value for each stream tube; and summing the derived values across all of the stream tubes.

Abstract: A control system operable includes a modified primary control parameter for an aircraft, the control system includes: a primary control parameter leg configured to output a demand in an aircraft primary control parameter; a primary control parameter compensation leg configured to receive a change in absolute levels and/or spatial distributions of swirl angle and/or fan pressure at a primary control parameter relative to a reference and convert the change into the primary control parameter; a processor adapted to receive the demand in the primary control parameter output from the primary control parameter leg and the change to the primary control parameter output from the primary control parameter compensation leg; compare the demand in the primary control parameter output from the primary control parameter leg and the change to the primary control parameter output from the primary control parameter compensation leg; and generate a modified primary control parameter for the aircraft.

Abstract: A gas turbine engine arrangement comprising a gas turbine engine and an inlet screen. The gas turbine engine comprises an engine core comprising an inlet having a radial extent extending from an engine longitudinal axis to a first radial position, and a fan duct comprising an inlet having a radial extent extending from the first radial position to a fan casing, the inlet screen comprising an at least part annular porous grid radially extending across at least part of the radial extent of the fan duct inlet, and not extending across any substantial part of the radial extent of the core inlet.

Abstract: A gas turbine engine arrangement comprising a gas turbine engine and an inlet screen. The gas turbine engine comprises an engine core comprising an inlet having a radial extent extending from an engine longitudinal axis to a first radial position, and a fan duct comprising an inlet having a radial extent extending from the first radial position to a fan casing, the inlet screen comprising an at least part annular porous grid radially extending across at least part of the radial extent of the fan duct inlet, and not extending across any substantial part of the radial extent of the core inlet.