Numerical study on influence of hydrofoil clearance towards total drag reduction on winged air induction pipe for air lubrication

A new device for air lubrication called the Winged Air Induction Pipe (WAIP) is studied in the present work. The device, which consists of an angled hydrofoil, uses the low-pressure region produced above the hydrofoil as a ship moves forward. The low pressure drives the atmospheric air into the water at certain velocities when the pressure is negative compared to atmospheric pressure. A computational fluid dynamics approach is presented in the study of the effect of the hydrofoil clearance of the Winged Air Induction Pipe on the drag reduction experienced by the plate to which the WAIP is attached. The well-known 'volume of fluid' model and k-SST (shear stress transport) turbulence closure model were used in the 2D numerical simulation in ANSYS Fluent. The numerical simulation was conducted with different hydrofoil clearance and angle of attack configurations, and the effects of these parameters on total drag force and drag reduction are reported. The reduction of drag force is found to increase by about 10% compared to the bare plate configuration.