An Unconfined Monocular Stereo-PIV Measurement Method for Gas-Liquid Pipe Flow

Stereo-particle image velocimetry (PIV) encounters intricate challenges in flow measurement, especially accurate target localization and synchronized control of dual cameras. To overcome these obstacles, a comprehensive study delves into gas-liquid two-phase flow utilizing a monocular Stereo-PIV system. To reduce the need for high-precision target localization, a method is proposed that integrates particle features for corner extraction and spatial consistency for precise matching by pyramid up-down sampling. The approach effectively mitigates scale variance-induced mismatches and facilitates accurate spatial plane reconstruction. Validation is conducted utilizing particle simulation to assess the accuracy of feature extraction and matching and their impact on spatial plane reconstruction. Furthermore, optical distortion calibration results derived from gas-liquid two-phase flow are compared with experimental data to investigate the accuracy of real plane reconstruction. The accuracy of 3-D velocities is evaluated across planes with various errors. Finally, 3-D velocity profiles are characterized within slug flow structures, thereby offering insights into velocity variation characteristics.