Fig. 1. Experimental system of gas-liquid two-phase flow

Fig. 2. Full liquid phase pipeline section

Fig. 3. Schematic diagram of ray tracing when there are bubbles in the pipe section

Fig. 4. Comparison of light intensity distributions (e~l) under different bubble phase distribution parameters (a~d). (a) All water; (b) (0,0,1); (c) (0,0,1.5); (d) (0.2,0.2,1.5)

Fig. 5. Schematic diagram of the parameter identification method

Fig. 6. Comparison of prediction results. (a) Single-wavelength; (b) Dual-wavelength

Fig. 7. Experimental setup

Fig. 8. Bubble flow. (a) x position; (b) y position

Fig. 9. Bubble radius distribution