Abstract: Apparatus and methods for reactance measurements are disclosed. The apparatus and methods are particularly suitable for eddy current proximity sensors in turbo-machine assemblies. In one arrangement, there is provided an apparatus comprising a circuit for receiving a sensing component of a sensor. The circuit has a unit having fixed reactance. An electrical source is provided for driving an alternating current through the circuit. An analysis unit measures the phase of a signal in the circuit that is dependent on the reactance of the sensing component. A measure of the reactance of the sensing component is output based on the measured phase.

Abstract: A multi-mode sensor includes an inductive sensor module configured to measure a first physical quantity based on magnetic induction. The inductive sensor module includes a coil wound around a coil axis. A non-inductive sensor module is provided to measure a second physical quantity using a non-inductive sensing mode. A portion of the non-inductive sensor module is radially inward of a portion of the coil relative to the coil axis.

Abstract: The invention relates generating timing signals registering the passage of a component past a sensor. The invention relates particularly to the generation of timing signals in real time for health monitoring of a mechanical system, for example for detecting excessive distortion or vibration of rotor blades in a turbine.

Abstract: The invention relates to detecting a composition of a sample or contamination in liquids by detecting corresponding changes in their thermal properties. In a disclosed arrangement, an apparatus is provided comprising a first probe element configured to provide a first surface in direct contact with the sample and a second surface that is not in direct contact with the sample. A measurement system measures a rate of heat transfer through the first surface. A processing unit analyses the measured rate of heat transfer in order to detect a heat transfer characteristic of the sample that is indicative of a composition of the sample.

Abstract: The invention relates generating timing signals registering the passage of a component past a sensor. The invention relates particularly to the generation of timing signals in real time for health monitoring of a mechanical system, for example for detecting excessive distortion or vibration of rotor blades in a turbine.

Abstract: The invention relates to a rotor assembly having a sealing system for sealing at apexes or faces of the rotor. In a disclosed arrangement the apex seal or the face seal comprises a compliant member that is configured such that the shape or orientation of the compliant member can change in use in response to a change in the speed of rotation of the rotor, a change in the pressurisation across the compliant member, or a change in clearance between the sealing surface and a mounting element to which the compliant member is mounted, to deflect towards or away from the sealing surface.

Abstract: Methods and apparatus for measuring the position of an object relative to a reference are disclosed. In an arrangement, a pressurized fluid is used to drive rotation of a cylinder around a piston and to bias the cylinder longitudinally. Ducts are provided in the cylinder and arranged so at to provide pulses of the fluid out of the cylinder through a reading port, the pulses being such as to uniquely identify the position of the cylinder relative to the piston and thereby of the object relative to the reference.

Abstract: The invention relates to a method of measuring turbulence in a high temperature fluid flow, comprising: applying different levels of cooling at different times to a region of a substrate in the high temperature fluid flow; and/or applying different levels of cooling at the same time to different regions of a substrate in the high temperature fluid flow and/or to regions on different substrates in the high temperature fluid flow, wherein the method further comprises: measuring fluctuations in the temperature of the region or regions of the substrate or substrates at each of the different levels of cooling; and using the measured fluctuations to determining an amount of turbulence in the high temperature fluid flow and/or the size of temperature fluctuations in the high temperature fluid flow.

Abstract: A method for monitoring local defects in a rotating engine component such as a gear uses one or more eddy current sensor(s) arranged to interact with the engine component as it is rotating during service. The eddy current sensor(s) may be carried by one or more teeth of a monitoring gear. A device is arranged to measure an output signal from the eddy current sensor(s) resulting from interaction with the rotating engine component. The output signal is processed so as to detect a change in shape of the output signal indicative of a local defect.

Abstract: The clearance between a stationary object (such as a gas turbine engine casing) and one or more moving objects (such as the blades of a rotating turbine) is measured using a pair of electrical proximity sensors mounted on the stationary object with their sensitive fields directed towards the path of the moving object(s) and at angle to each other. The clearance is calculated by deriving a time interval between interceptions of the respective moving object with the sensitive fields of the two sensors and from the geometry of the set up.

Abstract: An eddy current sensor for use as a dynamic proximity sensor, particularly for monitoring of blade tip timing and clearance in turbomachinery, has a common coil for use in both generating a magnetic field in a proximate region and detecting the effect of eddy currents generated by said field in electrically conductive objects passing through that region. The coil is wound on a rectangular or other elongate former so that the coil is itself elongate in section. This can improve the resolution of the device when used for sensing the passage of objects of elongate section (such as a turbine blade tip when the sensor coil is oriented with its shorter cross-sectional dimension aligned with the shorter cross-sectional dimension of the respective object. Also described is a method of processing a signal wave form from such devices to derive ‘trigger’ points for blade tip timing.

Abstract: A fluid temperature measurement probe, particularly for total temperature measurements in high temperature unsteady gas flows, such as in gas turbine engines. A pair of thin film resistance thermometers are deposited on the probe to sense its surface temperature at respective locations and the structure of the probe is configured such that the regions into which heat diffuses from the respective locations have different thermal products. In this way the thin film elements experience different heat transfer rates when exposed to the same fluid temperature. In one embodiment this is achieved by applying one of the elements to the surface of a solid rod of glass or ceramic and the other element to a portion which has been machined to leave an air pocket under a thin cylindrical wall of the rod material. In use the probe is exposed only temporarily to the high temperature fluid and withdrawn again before reaching its softening temperature.