Xiaoxiao Dong

Measuring Oil–Water Two-Phase Flow Velocity With Continuous-Wave Ultrasound Doppler Sensor and Drift-Flux Model

Oil-water two-phase flow is the main fluid form in petroleum industry. Since it is associated with safety operation and economic benefit, the flow velocity needs to be measured accurately. A method based on continuous-wave ultrasonic Doppler and drift-flux model is presented to estimate the overall superficial flow velocity of oil-water two-phase flow. A theoretical correlation combining velocity profile and drift-flux model was proposed to relate the measured velocity in the sensing volume of the ultrasonic Doppler sensor with the overall superficial velocity of two-phase flow. The measuring system consists of two piezoceramics ultrasonic transducers with a center frequency of 1 MHz and a PXI-based data acquisition system. Dynamic experiments involving five typical flow patterns were performed in a horizontal Plexiglas pipe with an inner diameter of 50 mm. The results show that the measuring system and the proposed method estimate the overall superficial flow velocity with an average error of 2.27%.

Oil–water two-phase flow measurement with combined ultrasonic transducer and electrical sensors

A combination of ultrasonic transducers operated in continuous mode and a conductance/capacitance sensor (UTCC) is proposed to estimate the individual flow velocities in oil–water two-phase flows. Based on the Doppler effect, the transducers measure the flow velocity and the conductance/capacitance sensor estimates the phase fraction. A set of theoretical correlations based on the boundary layer models of the oil–water two-phase flow was proposed to describe the velocity profile. The models were separately established for the dispersion flow and the separate flow. The superficial flow velocity of each phase is calculated with the velocity measured in the sampling volume of the ultrasonic transducer with the phase fraction through the velocity profile models. The measuring system of the UTCC was designed and experimentally verified on a multiphase flow loop. The results indicate that the proposed system and correlations estimate the overall flow velocity at an uncertainty of U J = 0.038 m s−1, and the water superficial velocity at U Jw = 0.026 m s−1, and oil superficial velocity at U Jo = 0.034 m s−1. The influencing factors of uncertainty were analyzed.

Water continuous oil-water flow velocity measurement based on continuous waves ultrasonic doppler method

A method for water continuous oil-water two-phase flow velocity measurement by using Continuous-Wave Ultrasonic Doppler (CWUD) technique is proposed. Two ultrasonic transducers with a center frequency of 1 MHz were used for emitting and receiving the ultrasound signals. The frequency of received signals changes with flow velocity, and these signals were collected through a PXI based data acquisition system. The acquired signals were transformed from time domain to frequency domain through Fast Fourier Transform (FFT) for obtaining the Doppler frequency shift. Theoretical models were set up to correlate the Doppler frequency shift with mean flow velocity. Experiments in a horizontal pipe were completed. The measured results show good agreement with reference flow velocity.

Gas–Liquid Two-Phase Flow Velocity Measurement With Continuous Wave Ultrasonic Doppler and Conductance Sensor

Flow velocity is an important process parameter that quantifies the volume or mass flow rate as well as monitors the process safety. To nonintrusively measure the flow velocity of horizontal gas–liquid two-phase flow, an ultrasonic Doppler sensor and a conductance sensor with dedicated measurement models are presented. The air superficial flow velocity can be directly obtained and the water superficial flow velocity can be calculated through a two-fluid model for bubble flow and plug flow. For slug flow, a correlation between the phase velocity in slug body and overall superficial flow velocity was built based on a slug closure model. In order to eliminate the influence of the changing velocity profile in the fluid, the sample volume was designed to cover the whole pipe cross section by installing a two-chip piezoelectric transducer with 1-MHz center frequency at the bottom of the pipe. The conductance sensor provided water holdup estimate to compensate the velocity measurement model. Experiments were carried out in a 50-mm inner diameter pipe to verify the proposed sensor and model. Three flow patterns (bubble flow, plug flow, and slug flow) were generated by adjusting the inlet flow rate of the air and the water. The results show that the mean relative error can achieve within 5%.