Oil-water two-phase flow velocity measurement based on ultrasonic Doppler and conductance ring

Two-phase flow exists widely in industrial field. Accurate measurement of the process parameters, such as flow velocity, is of great significance for quantifying flow rate and optimizing production process and equipment. A combination of one-side two-chip continuous wave ultrasonic Doppler (CWUD) sensor and conductance ring sensor is applied to measure the velocity in horizontal oil-water two-phase flow. The non-intrusive CWUD sensor consists of two-chip transducer with resonant frequency of 1 MHz, and there is a sound insulation material between the two chips to prevent sound waves from interfering. One chip continuously transmits sound wave to fluid, the other one receives the echo scattered from droplets. Consequently, its sample volume covers the whole radial range of pipe cross-section. The Doppler shift signal collected by CWUD sensor is directly related to the average velocity of dispersed phase within the sample volume. Dynamic experiments were conducted at a horizontal oil-water two-phase flow loop with a diameter of 50 mm. Based on the analysis of average Doppler shift response characteristic, it was found that there are two linear relationships between average Doppler shift and overall superficial flow velocity for different flow conditions, i.e. water and oil continuous flow condition. Hence, according to the electrical sensing principle of conductance ring sensor, a dimensionless voltage parameter is used to discriminate the continuous phase. And then for each experiment point, the corresponding measurement model is chosen to calculate the overall superficial flow velocity. The results show that the root mean square error of measured overall superficial flow velocity is 0.01 m/s and the average relative error is 3.09%. The confidence probability for relative error less than 5% is 70%.