Abstract
In this study, the Reynolds-averaged Navier–Stokes (RANS) method and a model experimental test in a towing tank are used to investigate the unsteady hydrodynamic performance of L-type podded propulsion under different oblique flow angles and advance coefficients. The results show that the load of the operative propeller increases with oblique flow angle and the bracket adds resistance to the pod due to the impact of water flow, leading to a reduced propeller thrust coefficient with increased oblique flow angle. Under a high advance coefficient, the speed of increase of the pressure effect is higher than that of the viscosity effect, and the propeller efficiency increases with the oblique flow angle. The nonuniformity of the inflow results in varying degrees of asymmetry in the horizontal and vertical distributions of the propeller blade pressure. Under high oblique flow angle, relatively strong interference effects are seen between venting vortexes and the cabin after blades, leading to a disorderly venting vortex system after the blade. The numerical simulation results are in good agreement with the experimental values. The study findings provide a foundation for further research on L-type podded propulsors.
Highlights
Podded propulsion can be used to both propel and manipulate a ship, including rotating it horizontally by 360◦
Chicherin et al [4] conducted a preliminary analysis of scale-affected podded propulsors using Reynolds-averaged Navier–Stokes (RANS) equation and investigated the influences of different advance coefficients and Reynolds numbers on pods and struts; their results suggested that the scale factor was a more effective predictor of the resistance performance of propulsors than the shape factor
Palm et al [15] conducted an experimental test and a computational fluid dynamics (CFD) simulation to investigate variations in the hydrodynamic performance of cycloidal and pusher podded propulsors for straight-ahead motion at various draft depths. They discovered that the pusher podded propulsor was influenced to a greater degree by the draft and that the thrust linearly decreased as the draft decreased, whereas only a portion of the cycloidal propeller blades were significantly affected by draft depth
Summary
Podded propulsion can be used to both propel and manipulate a ship, including rotating it horizontally by 360◦. Palm et al [15] conducted an experimental test and a CFD simulation to investigate variations in the hydrodynamic performance of cycloidal and pusher podded propulsors for straight-ahead motion at various draft depths They discovered that the pusher podded propulsor was influenced to a greater degree by the draft and that the thrust linearly decreased as the draft decreased, whereas only a portion of the cycloidal propeller blades were significantly affected by draft depth. In this study, based on the RANS method, the unsteady hydrodynamic performance of L-type podded propulsion under different oblique flow angles and advance coefficients is compared and analyzed by using slide grid technology and adjusting the size and direction of incoming flow. The study findings provide a foundation for further research on L-type podded propulsors
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