The effect of liquid droplets generated from air-assisted atomization on gas flow characteristics was studied experimentally. A phase/Doppler particle analyzer was used to measure velocity and size distributions of continuous and dispersed phases in the droplet-laden two-phase flow. A comparison of mean gas velocity with and without droplets indicates the expected influence of dispersed phase on the carrier phase, i.e., two-way coupling. The flow characterization result shows the presence of liquid droplets contributes to the increase of gas-phase flow velocity in the spray field. The effect of liquid droplets on gas-phase turbulence is manifested in three ways. First, the presence of droplets leads to the increase in fluctuation velocity of gas-phase flow. Subsequently, it is observed that the range of fluctuation velocities in the gas phase is expanded in two-phase flow compared with single-phase flow. In the region characterized by a steep velocity gradient, the initial gas fluctuation velocities in two-phase flow demonstrate a notable enhancement of 20% compared with single-phase flow. Furthermore, the presence of droplets induces axial stretching within the shear region of the gas phase, and this stretching effect is particularly pronounced in cases of higher fuel-injection durations, primarily due to the influence of droplet gravity. The data obtained from the analysis of velocity gradient and fluctuation velocity within the two-phase flow field reveal a distinct segmental linear relationship, deviating from previous findings reported in the literature and highlighting a deeper understanding of the underlying mechanisms in current two-phase flow systems.
Bibliographical noteKAUST Repository Item: Exported on 2023-09-11
Acknowledgements: The authors would like to acknowledge the research grant received from the National Natural Science Foundation of China (Grants No. 12072194 and No. 51806013), foundation research funds of the Ministry of Industry and Information Technology (Grant No. JCKY2019602D018), and Beijing Institute of Technology Research Fund Program for Young Scholars (Grant No. 2020CX04047). In addition, the authors appreciate the experimental facilities and necessary help provided by the State Key Laboratory of High Temperature Gas Dynamics of the Institute of Mechanics (CAS).