Jorge Muract

Comportamiento dinámico no-lineal de una turbina eólica sometida a la acción cargas aerodinámicas periódicas

Revista iberoamericana de ingeniería mecánica, Oct 1, 2013

Resumen -En este trabajo se presenta el desarrollo de simulaciones numéricas que permiten estudia... more Resumen -En este trabajo se presenta el desarrollo de simulaciones numéricas que permiten estudiar los aspectos que caracterizan la respuesta dinámica no-lineal de la estructura de una turbina eólica de eje horizontal sometida a la acción de las cargas aerodinámicas que actúan sobre el rotor. En la primera parte de este trabajo se derivan las ecuaciones de movimiento usando las ecuaciones de Lagrange, considerando restricciones del tipo no-holonómicas que son incorporadas de forma explicita a través de la introducción de multiplicadores de Lagrange. El modelo numérico incluye: (i) las palas que conforman el rotor de la turbina eólica, (ii) la barquilla, y (iii) la torre o estructura portante. Se considera a las palas como un conjunto de múltiples cuerpos rígidos vinculados perfectamente entre sí en el cubo o nariz del rotor. La barquilla y la torre se modelan como cuerpos con parámetros concentrados, incluyéndose la inercia rotacional de estos dos componentes. Las cargas aerodinámicas provenientes de la acción del viento sobre las palas que conforman el rotor se modelan como una carga distribuida de forma espacialmente invariante y con una magnitud variable en el tiempo. Los factores que gobiernan el cambio en magnitud de las cargas aerodinámicas son: (i) la velocidad de rotación del rotor y (ii) la variación de la velocidad del viento en altura por efecto de la rugosidad del terreno (presencia de la capa límite terrestre). Además de las cargas aerodinámicas, se consideran las cargas provenientes del amortiguamiento electromagnético, y de un momento de control proveniente del generador eléctrico. Este último es comúnmente utilizado como parámetro de control de la velocidad de rotación del rotor. Palabras clave -Energía eólica, aerogeneradores, turbinas eólicas, aerodinámica, simulaciones numéricas.

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Acoustic characterization of pneumatic percussion tools

Journal of the Acoustical Society of America, Sep 1, 2005

Pneumatic powered percussion tools are extensively used in construction industry. They are one of... more Pneumatic powered percussion tools are extensively used in construction industry. They are one of the noisiest machines in the construction industry generating noise levels well above 110 dBA which are well beyond the permissible exposure limit (PEL) of 85 dBA. The paper presents comprehensive analysis of the noise generated from these percussion tools. Noise tests were carried out on different percussion tools ranging from small chipping hammers to rock drills from two major construction equipment manufacturing companies. These tests were carried out in an anechoic room as well as in simulated operating conditions to determine the overall sound power levels. A spherical array of microphones was used to obtain an accurate estimate of the overall sound power levels and the directivity. The overall sound power radiation was found to be in the range of 105–115 dBA. An advanced 63 microphone phased array was used to successfully locate and identify the major sources of noise from these tools. The outcome of the tests is illustrated in detail in the paper. Further the paper will suggest noise control methods to reduce overall sound power radiation and discuss potential performance levels.

Hand transmitted vibration measurement using experimentally simulated hand‐arm rig

Journal of the Acoustical Society of America, Sep 1, 2005

Hand transmitted vibration (HTV) is one of the most common hazards faced by workers in the constr... more Hand transmitted vibration (HTV) is one of the most common hazards faced by workers in the construction industry. A major source of HTV is hand held percussion tools, such as pneumatically driven chipping hammers and rock drills. This paper presents a new approach to measuring the vibration from these tools using a mechanically simulated hand arm model to which the tools are attached. The simulated hand-arm model has been designed to have similar dynamic characteristics to that of a human hand-arm system. This approach addresses the issue of repeatability as HTV measurements suffer from variability between cases and from user to user. Different percussion tools ranging from a small chipping hammer to a rock drill, from two major construction equipment manufacturing companies, were used to conduct the vibration tests. The goals of these tests were to measure the vibration levels and to determine the most dominant modes of vibration. Comprehensive data analyses of the tests results are presented. Further, the paper discusses potential vibration control methods and expected performance levels.

Feasibility Study Of Microphone Phased Array Based Machinery Health Monitoring

Mecánica Computacional, 2007

To increase reliability and safety, industrial plant equipment such as compressors, electric moto... more To increase reliability and safety, industrial plant equipment such as compressors, electric motors, gear trains, and so forth are regularly monitored for damage. A traditional approach for monitoring is for a trained technician to make vibration measurements of the equipment. Inspection of the vibration measurements and their comparison to known healthy/damaged data sets allow for assessing the health status of the machines. This process is repeated at regular intervals. However, it is time-consuming and labor-intensive. It would be greatly convenient both in terms of time and cost to develop a remote acoustic based system to detect the health status of industrial equipment. A microphone phased array machine health monitoring system is proposed to remotely identify and classify machine faults. Acoustic spectral signature analysis has existed for many years, and it is similar to vibration analysis using accelerometers with the advantage that nothing must be mounted on the machine. In addition, acoustic imaging systems using microphone phased arrays have also been in existence for many years. The current state-of-the-art, however, requires an expert human operator to interpret the data from these devices, and therefore it is not suitable for automated, online monitoring. The implementation of a microphone phased array approach to monitor equipment faults in a typical industrial environment presents some unique challenges. A typical industrial plant is a highly acoustic reverberant environment that will result in significant reflections and background noise levels. To be effective, the array will need to be able to monitor multiple machines through the plant, simultaneously. To investigate the potential of the proposed approach, a numerical model of the microphone phased array in a large highly reverberant room was developed. The model was then used to investigate several array designs, study the effect of reflections and reverberation, determine the capability of the system to monitor multiple machines and so forth. These numerical studies revealed that the critical concern is that the array signal to noise ratio must be larger than the noise difference between the loudest and quietest machines being monitored. It was also found that the reverberation of typical industrial plants is not important if a sufficient number of microphones is used in the array, e.g. for a plant with an average absorption coefficient of 10% a minimum of 100 microphones is required in the array.

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Feasibility Study Of Microphone Phased Array Based Machinery Health Monitoring

To increase reliability and safety, industrial plant equipment such as compressors, electric moto... more To increase reliability and safety, industrial plant equipment such as compressors, electric motors, gear trains, and so forth are regularly monitored for damage. A traditional approach for monitoring is for a trained technician to make vibration measurements of the equipment. Inspection of the vibration measurements and their comparison to known healthy/damaged data sets allow for assessing the health status of the machines. This process is repeated at regular intervals. However, it is time-consuming and labor-intensive. It would be greatly convenient both in terms of time and cost to develop a remote acoustic based system to detect the health status of industrial equipment. A microphone phased array machine health monitoring system is proposed to remotely identify and classify machine faults. Acoustic spectral signature analysis has existed for many years, and it is similar to vibration analysis using accelerometers with the advantage that nothing must be mounted on the machine. I...

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Comportamiento dinámico no-lineal de una turbina eólica sometida a la acción cargas aerodinámicas periódicas

Revista Iberoamericana De Ingenieria Mecanica, 2013

Resumen -En este trabajo se presenta el desarrollo de simulaciones numéricas que permiten estudia... more Resumen -En este trabajo se presenta el desarrollo de simulaciones numéricas que permiten estudiar los aspectos que caracterizan la respuesta dinámica no-lineal de la estructura de una turbina eólica de eje horizontal sometida a la acción de las cargas aerodinámicas que actúan sobre el rotor. En la primera parte de este trabajo se derivan las ecuaciones de movimiento usando las ecuaciones de Lagrange, considerando restricciones del tipo no-holonómicas que son incorporadas de forma explicita a través de la introducción de multiplicadores de Lagrange. El modelo numérico incluye: (i) las palas que conforman el rotor de la turbina eólica, (ii) la barquilla, y (iii) la torre o estructura portante. Se considera a las palas como un conjunto de múltiples cuerpos rígidos vinculados perfectamente entre sí en el cubo o nariz del rotor. La barquilla y la torre se modelan como cuerpos con parámetros concentrados, incluyéndose la inercia rotacional de estos dos componentes. Las cargas aerodinámicas provenientes de la acción del viento sobre las palas que conforman el rotor se modelan como una carga distribuida de forma espacialmente invariante y con una magnitud variable en el tiempo. Los factores que gobiernan el cambio en magnitud de las cargas aerodinámicas son: (i) la velocidad de rotación del rotor y (ii) la variación de la velocidad del viento en altura por efecto de la rugosidad del terreno (presencia de la capa límite terrestre). Además de las cargas aerodinámicas, se consideran las cargas provenientes del amortiguamiento electromagnético, y de un momento de control proveniente del generador eléctrico. Este último es comúnmente utilizado como parámetro de control de la velocidad de rotación del rotor. Palabras clave -Energía eólica, aerogeneradores, turbinas eólicas, aerodinámica, simulaciones numéricas.

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Modelo analítico para predicción de ruido generado por la banda de rodadura

En vehículos motorizados existen diversas fuentes de ruido. El ruido producido por los vehículos ... more En vehículos motorizados existen diversas fuentes de ruido. El ruido producido por los vehículos puede ser molesto y estresante para los automovilistas y el medioambiente circundante, consecuentemente existe una demanda por vehículos cada vez más silencios. La industria responde a esta necesidad con el desarrollo de nuevas tecnologías para reducir el ruido de vehículos. De esa manera, los métodos de reducción de ruido implementados en los últimos 30 años llevaron a una transformación gradual de las fuentes de ruido dominantes distribuidas en un vehículo moderno. Por ejemplo, el ruido del escape ha sido controlado por la sucesión de simple, doble y triple cámara de expansión, llegando aproximadamente a una reducción de ruido de 6 dB por década. A finales de los 70s y principios de los 80s, la reducción del ruido vehicular se concentró en la unidad de potencia. Es interesante notar que al final de los 80s el neumático se convirtió en la principal fuente de ruido mientras que las otras...

Hand transmitted vibration measurement using experimentally simulated hand-arm rig

The Journal of the Acoustical Society of America, 2005

Hand transmitted vibration (HTV) is one of the most common hazards faced by workers in the constr... more Hand transmitted vibration (HTV) is one of the most common hazards faced by workers in the construction industry. A major source of HTV is hand held percussion tools, such as pneumatically driven chipping hammers and rock drills. This paper presents a new approach to measuring the vibration from these tools using a mechanically simulated hand arm model to which the tools are attached. The simulated hand-arm model has been designed to have similar dynamic characteristics to that of a human hand-arm system. This approach addresses the issue of repeatability as HTV measurements suffer from variability between cases and from user to user. Different percussion tools ranging from a small chipping hammer to a rock drill, from two major construction equipment manufacturing companies, were used to conduct the vibration tests. The goals of these tests were to measure the vibration levels and to determine the most dominant modes of vibration. Comprehensive data analyses of the tests results ar...

Acoustic characterization of pneumatic percussion tools

The Journal of the Acoustical Society of America, 2005

Pneumatic powered percussion tools are extensively used in construction industry. They are one of... more Pneumatic powered percussion tools are extensively used in construction industry. They are one of the noisiest machines in the construction industry generating noise levels well above 110 dBA which are well beyond the permissible exposure limit (PEL) of 85 dBA. The paper presents comprehensive analysis of the noise generated from these percussion tools. Noise tests were carried out on different percussion tools ranging from small chipping hammers to rock drills from two major construction equipment manufacturing companies. These tests were carried out in an anechoic room as well as in simulated operating conditions to determine the overall sound power levels. A spherical array of microphones was used to obtain an accurate estimate of the overall sound power levels and the directivity. The overall sound power radiation was found to be in the range of 105–115 dBA. An advanced 63 microphone phased array was used to successfully locate and identify the major sources of noise from these ...

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