PIV measurement of turbulent bubbly mixing layer

Based on the particle imaging velocimetry (PIV) measurement of single-phase mixing layer flow, the gas-liquid two-phase bubbly mixing layer with the velocity ratio 4:1 was experimentally investigated with PIV. The Reynolds number based on the velocity difference of two streams and hydraulic diameter of the channel ranged from 4400 to 158400. It was found that the bubbles injection could enhance the instantaneous velocity fluctuation when Reynolds number was small, but it would depress the instantaneous velocity fluctuation when Reynolds number was large. Afterwards the distributions of statistical Reynolds stress were obtained. Reynolds stress existed only in a very narrow region downstream of the mixing layer and increased with increasing Reynolds number. The distribution of Reynolds stress on the downstream cross-section showed that mean Reynolds stress value would decrease with bubble injection and there would be fluctuations on the same cross-section compared with the single-phase case.