Rolls-Royce

The disclosure relates to bidirectional current limiting circuits for use in aircraft electric power distribution system and methods for operating such bidirectional current limiters. A bidirectional current limiting circuit (400) comprises first and second parallel current paths (401, 402) connected between first and second terminals (403, 404), the first current path (401) comprising a first current limiting device (405) connected in series with a measurement inductor (406), the second current path (402) comprising a damping resistor (407) in series with a second current limiting device (408), wherein the first current limiting device is a first JFET (405), the circuit (400) further comprising a controller (409) connected to a gate of the first JFET (405), the controller (409) connected to receive a voltage measurement across the measurement inductor (406) and provide a first gate voltage to the first JFET (405) to restrict current through the first path (401) if the voltage measurement exceeds a voltage threshold.

This disclosure relates to bidirectional current limiting circuits for use in aircraft electric power distribution systems. Example embodiments include a bidirectional current limiting circuit (500a-c) comprising first and second JFETs (501, 502) connected between first and second terminals (503, 504), wherein: the first terminal (503) is connected to a drain of the first JFET (501) and to a gate of the second JFET (502) via a first biasing element (505, 701); he second terminal (504) is connected to a drain of the second JFET (502) and to a gate of the first JFET (501) via a second biasing element (506, 702); and a source of the first JFET (501) is connected to a source of the second JFET (502).

A method (200) for determining grain structure in a component (102) includes disposing the component (102) on a support platform (110). The method (200) includes generating an imaging beam (106). The method (200) includes rotating and/or revolving an imaging beam source (104) and an imaging beam receiver (108) relative to the support platform (110). The method (200) includes acquiring, during the rotation and/or revolution a plurality of projections (116) each taken at the imaging beam receiver (108). The method (200) includes performing reconstruction, by a processor (114), of first projections (116-1) and second projections (116-2) from the plurality of projections (116) to obtain a first three-dimensional image (120) and at least one second three-dimensional image (122). The first projections (116-1) are acquired in at least one first angular range (AR1) and the second projections (116-2) are acquired in at least one second angular range (AR2).

This disclosure relates to cooling modules for power electronics converters. Example embodiments include a cooling module (100) for a power electronics converter, comprising: first face (101) having a cooling liquid inlet (102); an opposing second face (103) having a cooling liquid outlet (104); a plurality of side walls (105a-d) extending between the first and second faces (101, 103), each side wall (105a-d) being configured for cooling a semiconductor switching device (106<1-6>) of the power electronics converter; and a helical cooling channel (107) extending through the cooling module between the cooling liquid inlet (102) and the cooling liquid outlet (104).

An aircraft gas turbine engine (103) comprises a fuel system comprising a first fuel line (108) configured to provide a first liquid hydrocarbon fuel to a combustor (203) of the gas turbine engine (103), and a second fuel line (109) configured to provide a second fuel, different to the first fuel, to the combustor (203) of the gas turbine engine (103). The gas turbine engine also comprises a hydraulic system configured to be driven by the first fuel during operation of the gas turbine combustor (203) when the gas turbine combustor utilises either or both of the first and second fuel.

A cleaning tool (100) for cleaning a component (50) located within a gas turbine engine (10) is disclosed. The cleaning tool (100) includes a tubular body (102) including: a first open end (104) and a second closed end (106); an engagement portion (108) that is proximal to the second closed end (106) and configured to engage with a support (110) within the gas turbine engine (10); a nozzle aperture (112) disposed between the first open end (104) and the engagement portion (108); and a flow channel (114) extending from the first open end (104) and in fluid communication with the nozzle aperture (112). The flow channel (114) is configured to transport a cleaning fluid (115) from the first open end (104) to the nozzle aperture (112). The cleaning fluid (115) is delivered to the component (50) through the nozzle aperture (112). The tubular body (102) is configured to be inserted through a first port (116) of the gas turbine engine (10) from the second closed end (106), such that the engagement portion (108) engages with the support (110).

An arrangement (1) for an electric machine (2, 2') comprises: a first winding system (WS1) and a second winding system (WS2), wherein at least one electrical conductor (120) of the first winding system (WS1) and at least one electrical conductor (121) of the second winding system (WS2) are at least partially wound around a common winding axis (A), wherein turns of the electrical conductors (120, 121) alternate in a direction of the winding axis (A); an inverter system (13) with a first inverter (134A) for the first winding system (WS1) and a second inverter (134B) for the second winding system (WS2); sensors (133) for sensing at least one electrical parameter of the first winding system (WS1) and at least one electrical parameter of the second winding system (WS2); and a control unit (131) configured to perform a test of the winding systems (WS1, WS2) by: controlling the first inverter (134A) to set the first winding system (WS1) to a first electrical potential (HV+) and/ot to control the second inverter (134B) to set the second winding system (WS2) to a second electrical potential (HV-) to create a potential difference between the winding systems (WS1, WS2); receiving corresponding sensor signals from the sensors (133); and analyzing the sensor signals.

There is disclosed an exhaust nozzle 30 for a gas turbine engine, comprising an exhaust structure 32 and a flap 34 configured to bound a passageway 36 through the exhaust structure. The flap 34 is coupled to the exhaust structure in a linkage arrangement configured to move the flap by compound translation and rotation with a single degree of freedom between a first orientation corresponding to a maximum throat area of the passageway and a second orientation corresponding to a minimum throat area of the passageway.

There is provided a method of monitoring the health of an asset. The method comprises obtaining a measured value of an input parameter representing an operational state of the asset, determining, based on the value, a residual that represents the behaviour of the asset, providing the determined residual to an encoder model to map the determined residual to a data point in a feature space, determining a distance of the data point relative to a cluster of data points in the feature space, wherein the cluster of data points are determined by the encoder based on residuals representing nominally healthy assets, and in response to the determined distance exceeding a predetermined distance threshold, generating an abnormal asset behaviour prediction.

There is provided a method of monitoring the health of an asset. The method comprises providing an input representing the behaviour of the asset to an encoder model to map the input to a data point in a feature space, wherein the encoder model is configured to cause data points relating to measured values of input parameters acquired from the asset at a similar time to cluster in feature space, determining a distance of the data point relative to a cluster of data points in feature space, where the cluster of data points are determined by the encoder based on inputs representing the asset over a first time period, and in response to the determined distance exceeding a predetermined distance threshold, generating an abnormal asset behaviour prediction.