286 research outputs found
Experimental investigations of two-phase flow measurement using ultrasonic sensors
This thesis presents the investigations conducted in the use of ultrasonic
technology to measure two-phase flow in both horizontal and vertical pipe flows
which is important for the petroleum industry. However, there are still key
challenges to measure parameters of the multiphase flow accurately. Four
methods of ultrasonic technologies were explored.
The Hilbert-Huang transform (HHT) was first applied to the ultrasound signals of
air-water flow on horizontal flow for measurement of the parameters of the two-
phase slug flow. The use of the HHT technique is sensitive enough to detect the
hydrodynamics of the slug flow. The results of the experiments are compared
with correlations in the literature and are in good agreement.
Next, experimental data of air-water two-phase flow under slug, elongated
bubble, stratified-wavy and stratified flow regimes were used to develop an
objective flow regime classification of two-phase flow using the ultrasonic
Doppler sensor and artificial neural network (ANN). The classifications using the
power spectral density (PSD) and discrete wavelet transform (DWT) features
have accuracies of 87% and 95.6% respectively. This is considerably more
promising as it uses non-invasive and non-radioactive sensors.
Moreover, ultrasonic pulse wave transducers with centre frequencies of 1MHz
and 7.5MHz were used to measure two-phase flow both in horizontal and
vertical flow pipes. The liquid level measurement was compared with the
conductivity probes technique and agreed qualitatively. However, in the vertical
with a gas volume fraction (GVF) higher than 20%, the ultrasound signals were
attenuated.
Furthermore, gas-liquid and oil-water two-phase flow rates in a vertical upward
flow were measured using a combination of an ultrasound Doppler sensor and
gamma densitometer. The results showed that the flow gas and liquid flow rates
measured are within ±10% for low void fraction tests, water-cut measurements
are within ±10%, densities within ±5%, and void fractions within ±10%. These
findings are good results for a relatively fast flowing multiphase flow
The characterisation of multicomponent (liquid) flows using scattered ultrasound.
The aim of this work is to determine the applicability of ultrasonic techniques to developing a non invasive flow meter capable of characterising multicomponent (liquid) flows. The possibility of detecting flow parameters such as velocity distributions, droplet/particle size distributions, spatial distribution and void fraction of the discontinuous phase has been investigated.
An early consideration of the likely applications of this meter, revealed that an ultrasonic technique would be the most versatile and suitable. Consequently, a theoretical study of the interaction of an ultrasonic wave and a disperse system has been carried out, as well as a study of the possible regimes where these principles may be applied.
The work begins from first principles, studying both experimentally and theoretically the interaction of an acoustic wave with a single particle. This is then extended to characterising a flowing multicomponent system on a larger scale.
The nature of complex flows was then investigated from the point of view of a chaotic dynamical system. Both theoretical and experimental methods show this to be a valid approach to understanding the flow of mixtures.PhD in Engineerin
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National laboratories` capabilities summaries for the DOE Virtual Center for Multiphase Dynamics (VCMD)
The Virtual Center For Multiphase Dynamics (VCMD) integrates and develops the resources of industry, government, academia, and professional societies to enable reliable analysis in multiphase computational fluid dynamics. The primary means of the VCMD focus will be by the creation, support, and validation of a computerized simulation capability for multiphase flow and multiphase flow applications. This paper briefly describes the capabilities of the National Laboratories in this effort
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