Measurement of Multiphase Flow by Tilted Optical Fiber Bragg Grating Sensor

Measuring multiphase flows is essential in the oil and gas industry and medicine, as well as to microfluidic-based analyses. This article presents an optical fiber sensor for assessing the speed of two-phase flows based on tilted fiber Bragg grating (TFBG). As the dispersed slugs pass by the grating, resonance dips of cladding modes shift and work like a notch filter for a given wavelength; therefore, the TBFG can be interrogated in real-time according to an intensity-based, single-wavelength setup. The system is validated for samples comprised of water, oil, and air, yielding maximum relative error of 4.4% for speed measurements, whereas the sensor response can be tailored for different fluids by choosing the wavelength of the input light.