Experimental demonstration of 4D imaging in two-phase flows based on computed tomography at 5 kHz.

Turbulent flows inherently feature 3D spatial structures and temporal dynamics. As a result, 4D experimental techniques have been long desired to fully resolve turbulent flows in all three spatial directions and time. This work describes the demonstration of such 4D measurements in two-phase flows using computed tomography and Mie scattering. Demonstration measurements were performed in airflows seeded with water droplets at a 5 kHz frame rate, with an exposure time of 0.2 ms and a measurement volume of 85  mm×85  mm×85  mm discretized into 128×128×128 voxels. Experimental and computational studies have been conducted, with a focus on comparison and validation of the 3D reconstructions against experiments performed in flows with recognizable patterns.