The oil-water two-phase flow experiment was carried out in a vertical upward pipe to study the responses of the pulsed ultrasonic sensor and vertical multiple electrode array sensor. Based on the finite element calculation, it is found that the calculated ultrasonic levels are very sensitive to the concentration variations of dispersed oil phase, and the oil droplet diameter can affect the ultrasonic field. Moreover, the technique of symbolic dynamic filtering is used to analyze the ultrasonic fluctuating signals, and extract the anomaly flow measure from the signals of ultrasonic sensor. The results show that, the anomaly flow measure linearly increases when the oil volume fraction y(o) is lower than 0.35. However, for higher oil volume fraction (y(o) > 0.35) the variation of flow measure presents an irregular distribution with the change of oil volume fraction. These interesting and significant findings suggest that the pulsed ultrasonic technique can potentially be a powerful tool for measuring the high water volume fraction of dispersed oil-in-water two-phase flows. (c) 2013 Elsevier Ltd. All rights reserved.