Interfacial Dynamics Around a Swirling Roller in the Presence of Oppositely Imposed Horizontal Crossflows

Abstract

The behavior of interfacial dynamics around a swirling circular drum is reported in the presence of horizontal crossflows of gaseous phase. A constant submergence ratio of the rotary drum is considered throughout this work. Forward and reverse crossflows are defined based on the direction of rotation of drum. A clockwise rotation is imposed on the drum and the rotation direction remains fixed throughout the present investigation. The pattern of film flow and cusp entrainment is observed thoroughly by considering rotational speed (ω) and strength of crossflow as influencing parameters. Strength of crossflow of gaseous phase is calibrated using flow Reynolds number based on roller diameter (Reflow=ρgUD/μg). Subsequently, we characterized the coated film thickness (h*=h/D) and cusp width (H*=H/D) by varying ω and Reflow. Furthermore, efforts are made to observe the influence of gravitational pull (calibrated using Archimedes number, Ar) and viscous drag (determined using Morton number, Mo) on interfacial morphology. The interfacial structures respond more to the rotational inertia compared to crossflow with the continuous increase of Mo. Again, the trailing end of cusp gets widened for the case of forward crossflow, whereas the cusp growth is obstructed in the presence of reverse crossflow, which is visualized using velocity vectors. We have also predicted appropriate correlations for film thickness (h*), cusp width (H*), and steady cusp length (θs*) in the presence of forward as well as reverse crossflow of air stream. Lastly, a theoretical framework is also developed to estimate film thickness and cusp width for both cases of crossflows and this framework agrees well with the simulated predictions.