Study on the Effect of Flap Parameters on Hydrodynamic Characteristics of Marine Flap Rudder

By tweaking the flap’s deflection angle, the flap rudder significantly enhances the hydrodynamic performance. This study investigates the influence of the location of the flap rotation axis and the size of the flap’s deflection affect how well the rudder performs in the water, using computer simulations to obtain high-resolution flow-field data. The results demonstrate that the flap rudder consistently generates more lift than your standard rudder. Prior to stall, pushing the flap rotation axis further back results in less lift, but also less drag. For maximum lift at small or moderate angles of attack, a rotation axis located at 0.75 c provides the highest lift coefficient, whereas the 0.85 c configuration combined with δ = 25° offers the best compromise between postponed stall and maintained lift-to-drag ratio. Put the pivot at 85% chord and set the flap deflection to 25 degrees, and an optimal configuration is achieved in terms of lift and drag. The configuration yields a stall angle pushed out to 16 degrees and a maximum lift coefficient that jumps to 3.86. That’s a significant increase of 15.77 % over what you’d get with 15° flap deflection. Ultimately, this research lays the groundwork for designing better flap rudders and gives us some serious pointers on how to increase the performance of ship rudders in the real world.