A Comparative Study on Hydrodynamic Performance of Double Deflector Rectangular Cambered Otter Board

Abstract

In the present work, the hydrodynamic performance of the double deflector rectangular cambered otter board was studied using wind tunnel experiment, flume tank experiment and numerical simulation. Results showed that the otter board had a good hydrodynamic performance with the maximum lift-to-drag ratio (KMAX = 3.70). The flow separation occurred when the angle of attack (AOA) was at 45°, which revealed that the double deflector structure of the otter board can delay the flow separation. Numerical simulation results showed a good agreement with experiment ones, and could predict the critical AOA, which showed that it can be used to study the hydrodynamic performance of the otter board with the advantage of flow visualization. However, the drag coefficient in flume tank was much higher than that in wind tunnel, which resulted in a lower lift-to-drag ratio. These may be due to different fluid media between flume tank and wind tunnel, which result in the big difference of the vortexes around the otter board. Given the otter boards are operated in water, it was suggested to apply both flume tank experiment and numerical simulation to study the hydrodynamic performance of otter board.