Flow characteristics in a heterogeneous bubbly flow associated with a top-submerged lance gas injection

• Heterogeneous and anisotropic TSL flows were characterized by TR-PIV experimental data. • Different TKE transfer behaviors of the TSL flow were clarified. • An inverse energy transfer phenomenon was noticed in the TSL flow. • Insights into the TSL flow characteristics have been provided. Bearing very different flow features to the widely studied homogeneous bubbly flow, the flow formed by top-submerged lance (TSL) gas injection, i.e ., TSL flow, possesses heterogeneous and anisotropic properties. Time-resolved particle imaging velocimetry (TR-PIV) experiments were performed to measure the flow data. The results show that a large vortical region are present in the near-wall, in the near-interface and in the bubbly regions. Besides, small vortical regions are dispersed in the shear dominated region. The probability density function (PDF) profiles of the velocity fluctuations indicate that the TSL flow is clearly anisotropic. The heterogeneous flow regimes result in a different turbulent kinetic energy (TKE) transfer behavior. A f -5/3 scaling and f -3 scaling of the energy spectrum were observed, and the two scalings can coexist in specific flow regimes. In addition, an inverse energy transfer phenomenon characterized by a negative turbulent production was noticed in the TSL flow.