Simulating eddy current sensor outputs for blade tip timing

Blade tip timing is a contactless method used to monitor the vibration of blades in rotating machinery. Blade vibration and clearance are important diagnostic features for condition monitoring, including the detection of blade cracks. Eddy current sensors are a practical choice for blade tip timing and have been used extensively. As the data requirements from the timing measurement become more stringent and the systems become more complicated, including the use of multiple sensors, the ability to fully understand and optimize the measurement system becomes more important. This requires detailed modeling of eddy current sensors in the blade tip timing application; the current approaches often rely on experimental trials. Existing simulations for eddy current sensors have not considered the particular case of a blade rotating past the sensor. Hence, the novel aspect of this article is the development of a detailed quasi-static finite element model of the electro-magnetic field to simulate the integrated measured output of the sensor. This model is demonstrated by simulating the effect of tip clearance, blade geometry, and blade velocity on the output of the eddy current sensor. This allows an understanding of the sources of error in the blade time of arrival estimate and hence insight into the accuracy of the blade vibration measurement

Accuracy Characterization of a MEMS Accelerometer for Vibration Monitoring in a Rotating Framework

Active and passive vibration control systems are of paramount importance in many engineering applications. If an external load excites a structure’s resonance and the damping is too low, detrimental events, such as crack initiation, growth and, in the worst case, fatigue failure, can be entailed. Damping systems can be commonly found in applications such as industrial machines, vehicles, buildings, turbomachinery blades, and so forth. Active control systems usually achieve higher damping effectiveness than passive ones, but they need a sensor to detect the working conditions that require damping system activation. Recently, the development of such systems in rotating structures has received considerable interest among designers. As a result, the development of vibration monitoring equipment in rotating structures is also a topic of particular interest. In this respect, a reliable, inexpensive and wireless monitoring system is of utmost importance. Typically, optical systems are used to measure vibrations, but they are expensive and require rather complex processing algorithms. In this paper, a wireless system based on a commercial MEMS accelerometer is developed for rotating blade vibration monitoring. The proposed system measurement accuracy was assessed by means of comparison with a reference wired measurement setup based on a mini integrated circuit piezoelectric (ICP) accelerometer adapted for data acquisition in a rotating frame. Both the accelerometers were mounted on the tip of the blade and, in order to test the structure under different conditions, the first four blade resonances were excited by means of piezoelectric actuators, embedded in a novel experimental setup. The frequency and amplitude of acceleration, simultaneously measured by the reference and MEMS sensors, were compared with each other in order to investigate the viability and accuracy of the proposed wireless monitoring system. The rotor angular speed was varied from 0 to 300 rpm, and the data acquisitions were repeated six times for each considered condition. The outcomes reveal that the wireless measurement system may be successfully used for vibration monitoring in rotating blades

Advanced photonic sensors for industrial applications

380 p.En esta tesis se han desarrollado diversos sensores basados en fibra óptica cuya finalidad es ofrecer una alternativa o solución a las necesidades particulares de la industria. En este contexto, las fibras ópticas y la fotónica en general son especialmente atractivas gracias a características intrínsecas que poseen, como su pequeño tamaño y alta sensibilidad, por ejemplo, lo que ha aumentado el interés por parte del sector industrial en esta tecnología.En la primera parte de la tesis, se describe el proceso llevado a cabo para el diseño y fabricación de sensores ópticos para la medida sin contacto del parámetro llamado Tip Clearance (TC) en motores aeronáuticos. El TC consiste en medir la distancia (del orden de micrómetros) entre los álabes que están girando a altas revoluciones y la carcasa del motor, y, por tanto, es un parámetro de suma importancia para la industria aeronáutica tanto a nivel de seguridad como de eficiencia del motor. Dichos sensores fueron puestos a pruebas en el túnel de viento del Centro de Tecnologías Aeronáutcas (Zamudio, Bizkaia) con buenos resultados.En la segunda parte de la tesis se han diseñado y fabricado sensores basados en fibra multinúcleo particularizados específicamente para la medida de diversos parámetros como la temperatura,vibraciones, curvatura, bending, etc. que son de interés para la industria. Dichos sensores mostraron una alta sensibilidad, lo que unido a su simplicidad y pequeño tamaño los convierte en una alternativa interesante tanto para su integración en cadenas de producción como para su uso en test de validación

Advanced photonic sensors for industrial applications

380 p.En esta tesis se han desarrollado diversos sensores basados en fibra óptica cuya finalidad es ofrecer una alternativa o solución a las necesidades particulares de la industria. En este contexto, las fibras ópticas y la fotónica en general son especialmente atractivas gracias a características intrínsecas que poseen, como su pequeño tamaño y alta sensibilidad, por ejemplo, lo que ha aumentado el interés por parte del sector industrial en esta tecnología.En la primera parte de la tesis, se describe el proceso llevado a cabo para el diseño y fabricación de sensores ópticos para la medida sin contacto del parámetro llamado Tip Clearance (TC) en motores aeronáuticos. El TC consiste en medir la distancia (del orden de micrómetros) entre los álabes que están girando a altas revoluciones y la carcasa del motor, y, por tanto, es un parámetro de suma importancia para la industria aeronáutica tanto a nivel de seguridad como de eficiencia del motor. Dichos sensores fueron puestos a pruebas en el túnel de viento del Centro de Tecnologías Aeronáutcas (Zamudio, Bizkaia) con buenos resultados.En la segunda parte de la tesis se han diseñado y fabricado sensores basados en fibra multinúcleo particularizados específicamente para la medida de diversos parámetros como la temperatura,vibraciones, curvatura, bending, etc. que son de interés para la industria. Dichos sensores mostraron una alta sensibilidad, lo que unido a su simplicidad y pequeño tamaño los convierte en una alternativa interesante tanto para su integración en cadenas de producción como para su uso en test de validación

Study of the turbocharger shaft motion by means of infrared sensors

This work describes a technique for measuring the precession movement of the shaft of small automotive turbochargers. The main novelty is that the technique is based on infrared light diode sensors. With presented technique it is possible to perform secure mounting of electronics and also to measure, with good accuracy, far enough from the turbocharger shaft. Both advantages allow applying it even in critical lubrication conditions and when blade contact occurs. The technique's main difficulties arise from the small size of the turbocharger shaft and the high precession movement in critical conditions. In order to generate the optimum albedo reflection for infrared measurement, a special cylindrical nut with larger diameter than the original one is assembled at the shaft tip in the compressor side. Following, shaft balancing, the calibration of the sensors and the compensation of errors from different sources are needed steps before the method is able to identify the main frequencies of shaft motion. Once synchronous and sub-synchronous frequencies have been obtained it is possible to reconstruct the instantaneous position of the shaft to determine its precession movement.This research has also been partially supported by the Programa de Desarrollo del Talento Humano de la Secretaria Nacional de Educacion Superior, Ciencia, Tecnologia e Innovacion del Gobierno Ecuatoriano No. 20100289.Serrano Cruz, JR.; Guardiola, C.; Dolz García, VM.; López, M.; Bouffaud, F. (2015). Study of the turbocharger shaft motion by means of infrared sensors. Mechanical Systems and Signal Processing. 56-57:246-258. https://doi.org/10.1016/j.ymssp.2014.11.006S24625856-5

Sensing Applications in Aircrafts Using Polymer Optical Fibres

We report on recent advances in the use of inexpensive polymer optical fibres (POFs) for sensing applications in avionics. The sensors analysed in this manuscript take advantage of the unique properties of polymers, such as high flexibility, elasticity, and sensitivity, and they range from strain, elongation, and vibration interrogators to level and temperature meters, leading to cost-effective techniques for structural health monitoring in aircraft structures. We also highlight recent power-supply methods using Power-over-POF in order to feed sensors remotely, and we discuss the constraints imposed by connectors on the performance of POF networks in aircrafts

Unsteady Aerodynamics and Blade-Row Interactions in the Embedded Stage of an Axial Compressor

In a mature engineering field like compressor aerodynamics, the most accessible advances in machine technology, translating to performance and efficiency, have been discovered and have found industry design applications. As the community continues to make progress, increasingly challenging aspects of the involved physics must be exploited. Modern turbomachinery operates with larger bypass ratios, smaller cores, and lighter, thinner, and more flexible materials resulting in the maintenance of higher operating pressures and temperatures. As the performance and efficiency of these machines continues to climb, the same technological advances reinforce challenges like forced-response vibration, high-cycle fatigue of engine components, and large relative tip clearances in an engine core. Accounting for these challenges increasingly depends on the investigation of the unsteady domain for solutions. Tools at the disposal of the designer include progressively improving computational simulations through both computational resources and attainable model fidelity. As essential as these tools are for modern turbomachinery design, the confidence in their results is only as good as the experimental data used to validate them. The objective of this research is the experimental investigation and characterization of the transient aerodynamics and blade-row interactions near forced-response resonant vibratory operating conditions in a multi-stage environment. Experimental methods are focused on fast-response pressure transducers with the high frequency response capable of capturing the unsteady pressure fluctuations associated with the high-speed rotation and blade-pass frequency of a modern high-pressure core axial compressor. Investigation is centered on an engine-representative embedded rear stage, with adjacent stages establishing realistic flow conditions and resulting boundary conditions for model comparison. Aerodynamic characterization of several flow conditions and the examination of the effect of a reduced vane-count stator configuration upstream of the embedded stage are performed with measurements of the embedded rotor at the casing endwall and rotor exit plane, as well as within a passage of the embedded stator. Circumferential vane traverse around stationary instrumentation provide a full vane passage of phase-locked, time-resolved pressure measurements of the rotor aerodynamics and the unsteady loading of the embedded stator is distinguished for a single vane position. Results from this investigation identify and describe the inception and trajectory of tip clearance flows, including the tip leakage vortex and double-leakage tip clearance flow. Evidence of an upstream vane wake interaction with the rotor occurs for limited regions of vane passage positions. Spectral analyses and pressure unsteadiness provide further insight into the blade-row interactions

Development and Testing of Propulsion Health Management

An Integrated Vehicle Health Management system aims to maintain vehicle health through detection, diagnostics, state awareness, prognostics, and lastly, mitigation of detrimental situations for each of the vehicle subsystems and throughout the vehicle as a whole. This paper discusses efforts to advance Propulsion Health Management technology for in-flight applications to provide improved propulsion sensors measuring a range of parameters, improve ease of propulsion sensor implementation, and to assess and manage the health of gas turbine engine flow-path components. This combined work is intended to enable real-time propulsion state assessments to accurately determine the vehicle health, reduce loss of control, and to improve operator situational awareness. A unique aspect of this work is demonstration of these maturing technologies on an operational engine

Manufacturing Metrology

Metrology is the science of measurement, which can be divided into three overlapping activities: (1) the definition of units of measurement, (2) the realization of units of measurement, and (3) the traceability of measurement units. Manufacturing metrology originally implicates the measurement of components and inputs for a manufacturing process to assure they are within specification requirements. It can also be extended to indicate the performance measurement of manufacturing equipment. This Special Issue covers papers revealing novel measurement methodologies and instrumentations for manufacturing metrology from the conventional industry to the frontier of the advanced hi-tech industry. Twenty-five papers are included in this Special Issue. These published papers can be categorized into four main groups, as follows: Length measurement: covering new designs, from micro/nanogap measurement with laser triangulation sensors and laser interferometers to very-long-distance, newly developed mode-locked femtosecond lasers. Surface profile and form measurements: covering technologies with new confocal sensors and imagine sensors: in situ and on-machine measurements. Angle measurements: these include a new 2D precision level design, a review of angle measurement with mode-locked femtosecond lasers, and multi-axis machine tool squareness measurement. Other laboratory systems: these include a water cooling temperature control system and a computer-aided inspection framework for CMM performance evaluation