This work shows the application of an ultrasonic multiple-scattering sensor for monitoring water-in-petroleum emulsions. The sensor consists of a commercial ultrasonic transducer with an array of cylindrical scatterers placed in the near field. The scatterers are thin metal bars arranged in rows in front of the transducer. The backscattering signals were analyzed by calculating the wave energy and by a cross-correlation between signal segments; they were also used to determine the propagation velocity in the emulsions. The tests performed used emulsions with water volume concentrations from 0 to 50%. The results showed that both the signal energy and propagation velocity strongly depended on the concentration of water in the emulsion. Therefore, the ultrasonic multiple-scattering sensor can be used for on-line and real-time monitoring of the water content in water-in-crude-oil emulsions.
This work proposes the slope of the phase spectrum as a signal processing parameter for the ultrasonic monitoring of the water content of water-in-crude oil emulsions. Experimental measurements, with water volume fractions from 0 to 0.48 and test temperatures of 20 °C, 25 °C, and 30 °C, were carried out using ultrasonic measurement devices operating in transmission–reception and backscattering modes. The results show the phase slope depends on the water volume fraction and, to a lesser extent, on the size of the emulsion droplets, leading to a stable behavior over time. Conversely, the behavior of the phase slope as a function of the volume fraction is monotonic with low dispersion. Fitting a power function to the experimental data provides calibration curves that can be used to determine the water content with percentage relative error up to 70% for a water volume fraction of 0.06, but less than 10% for water volume fractions greater than 0.06. Furthermore, the methodology works over a wide range of volume fractions.
Este trabalho apresenta um algoritmo implementado em GPU, para calcular o campo acústico produzido por um transdutor ultrassônico com excitação contínua, emitindo em água. A pressão acústica em um ponto do espaço, na frente do transdutor, é calculada mediante a integral de Rayleigh, a qual utiliza o princípio de Huygens para considerar o campo de pressão como a soma da contribuição de um número infinito de fontes pontuais. Dado que a pressão em cada ponto do espaço pode ser calculada de forma independente, o algoritmo pode ser executado em paralelo, aproveitando a vantagem dos núcleos da GPU. Foi analisado o desempenho do algoritmo proposto realizando alguns testes na faixa de frequência de 0,25 a 5,0 MHz. A superfície de emissão foi discretizada com a finalidade de obter um determinado número de elementos finitos de área. Foi possível validar os campos acústicos simulados usando o valor teórico da pressão ao longo do eixo de simetria do transdutor. Adicionalmente, a análise de desempenho mostrou que a GPU foi 50 vezes mais rápida que a CPU, para os problemas mais demandantes.
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