Bulletin of the American Physical Society
77th Annual Meeting of the Division of Fluid Dynamics
Sunday–Tuesday, November 24–26, 2024; Salt Lake City, Utah
Session J14: General Fluid Dynamics: Rotating Flows |
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Chair: Mustafa Usta, Cleveland State University Room: 155 D |
Sunday, November 24, 2024 5:50PM - 6:03PM |
J14.00001: Characterizing flow and pressure dynamics of annulus flow between two rotating permeable discs Mertcan Samgar, Cosan Daskiran, Mustafa Usta This study investigates the hydrodynamics of incompressible annular flow between two uniformly rotating, porous discs, in contrast to previous research focused on impermeable discs. The porous nature of these discs introduces no-slip but selectively permeable boundary conditions, significantly modifying the velocity and shear profiles. Through highly resolved laminar and LES simulations, we examine the effects of mass transfer through the porous medium on bulk flow dynamics, with flow rates through the discs reaching up to 50% of the inlet flow. Our findings reveal that the formation of Ekman layers, characterized by high peak velocities near the walls, plays a crucial role in determining the wall shear stress distribution and influencing the advective behavior of species near the wall. Additionally, the combined effects of rotation-induced centrifugal force and wall flux reduce the bulk flow rate, profoundly affecting the radial pressure distribution. Understanding these pressure dynamics is essential, as they are key drivers of the pressure-driven separation process by impacting local flux. Overall, this study aims to show how these altered flow dynamics theoretically influence the conditions that affect species transport, leading to accumulation along the porous surfaces. By characterizing pressure dynamics and shear profiles under varying rotation rates, flow rates, and flux rates, we aim to optimize separation efficiency in pressure-driven systems. |
Sunday, November 24, 2024 6:03PM - 6:16PM |
J14.00002: "Changing gears:" flow-mediated coupling of spinning cylinders Jesse Smith, Leif Ristroph, Jun Zhang Solid body interactions mediated by a flow are ubiquitous in the natural world. Flow-mediated interactions between spinning degrees of freedom play a basic role in more complicated fluid-structure interactions and have been variously studied in active matter, mixing, and renewable energy contexts. To bring these disparate experiments into a canonical fluid-dynamical setting, we study the interactions of two immersed cylinders at intermediate Taylor number. Inspired by mechanical gears, one of the cylinders is driven to rotate while the other can passively respond with rotation of its own. Unlike mechanical gears which rotate in opposite directions, we find that the passive cylinder can rotate in either direction relative to the active cylinder. We demonstrate that this bifurcation is caused by a three-dimensional Taylor instability between the cylinders. We also find that confining boundaries have a strong effect on the phase space of these spin-switching bifurcations, suggesting new directions in the geometric control of flow-coupled interaction. |
Sunday, November 24, 2024 6:16PM - 6:29PM |
J14.00003: Experimental investigation on the liquid flows induced in a rotating drum Daeun Lee, Jaebeen Lee, Seok Min Choi, Sangtak Lee, Hyungmin Park The rotating drum (circular cylindrical chamber with a short aspect ratio) aligned horizontally, whether it is fully or partially filled with liquid and/or solid particles, is encountered in many engineering applications for mixing, drying, coating, and cleaning. In the present study, the liquid flow induced in a rotating drum is investigated with different fill ratios. For each fill ratio, controlled by varying the water height, we measure the velocity fields at different cross-sectional planes with particle image velocimetry while varying the rotational speed of the drum. We compare the flow structure developed in the partially filled conditions with the condition of a fill ratio of 1.0, in which the liquid inside the drum rotates forming a large-scale organized flow structure. In addition to the mean flow structure, we examine the fluctuating velocity fields together with the dynamics of the free surface. Depending on fill ratio (< 1.0) and rotational speed, it is found that the counter-acting effects by the centrifugal (viscous) and gravitational forces cause quite complicated flow structures inside the drum. We also report the differences between the liquid flow and granular (particle) flow in a partially filled drum. |
Sunday, November 24, 2024 6:29PM - 6:42PM |
J14.00004: Reduced order model to predict volute tongue-induced unsteady loading on a radial turbine blade Chhote Lal Shah, Daniel J Bodony Turbochargers (T/Cs) are extensively utilized in the automotive industry due to their ability to augment the output of an internal combustion engine without necessitating an increase in cylinder capacity. In aviation, turbochargers adapted from ground-based applications are frequently employed in intermittent combustion engines to enhance efficiency and performance. However, these turbochargers often operate under off-design conditions and are susceptible to blade failures caused by aerodynamic-induced resonances. In this study, a one-dimensional (1D) methodology is employed to model the T/C turbine, integrating a T/C dynamic model with a flow model to simulate unsteady loading within the turbine. The model resolves the turbine volute flow using 1D viscous equations, taking into account the volute curvature and the circumferentially continuous flow exiting at the volute outlet. The turbine rotor is modeled using a meanline approach. This model is adept at predicting tongue-induced unsteady loading and provides the necessary parameters for subsequent three-dimensional simulations. The 1D results are currently compared with those obtained from three-dimensional unsteady simulations. This comparison aims to validate the 1D model's capability in accurately predicting unsteady loading on the T/C radial turbine blade. |
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