An optical fiber multiphase flow sensor based on identification of bubble collision and bounce

In this paper, we proposed a Fiber Bragg Grating (FBG) based on identification of bubble collision and bounce. The FBG target sensor detects the vibration signal resulting from the multiple rebound motions of the bubble after colliding with the target. The tension, diameter, and velocity of the bubbles are related to the frequency and amplitude of the vibration signal. In the test of a single target sensor, the frequency of air bubbles is measured to be within the range of 80-100 Hz which is higher than the frequency of oil bubbles within the range of 0-10 Hz. An annular sensing array based on a 3D printed structure is also demonstrated for measuring the cross-sectional bubbles passing through the pipeline. The proposed sensor introduces a new multiphase sensing principle, paving a way for optical fiber holdup sensor development.