Oil–water two-phase flow velocity measurement with continuous wave ultrasound Doppler

•Present a continuous wave ultrasonic Doppler method to measure oil–water two-phase flow velocity.•Velocity profile based theoretical correlations are established for stratified flow and dispersed flow.•Dispersed flow correlations are developed for oil-continuous flow and water-continuous flow.•The stratified flow model is based on the non-axisymmetric velocity profile.

A flow velocity measurement method based on continuous wave ultrasound Doppler (CWUD) and flow profile modeling is presented. A theoretical model is proposed to relate the overall superficial velocity of oil–water two-phase flow with the mean velocity measured in the sensing volume of CWUD, by introducing velocity profile correlation. A CWUD measuring system was built to emit an ultrasonic wave of 1 MHz and collect the frequency shift of the reflected waves. Dynamic experiments were carried out in a horizontal pipe of inner diameter of 50 mm with the CWUD system. Six flow patterns of horizontal oil–water two-phase flow were observed including both the water continuous flow and the oil continuous flow. According to the results, the average frequency shift in oil–water two-phase flow varies with the flow pattern. The flow velocity correlations are separately established for the oil continuous dispersed flow, water continuous dispersed flow and stratified flow, based on the analysis of flow velocity profile correction. The average relative error of the overall superficial velocity is 3.63% with a maximum relative error of 12.22%.

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