Influence of main-panel angle on the hydrodynamic performance of a single-slotted cambered otter-board

The effect of the main-panel angle of a single-slotted cambered otter-board was investigated using engineering models in a wind tunnel. Three different angles (0°, 6°, and 12°) were evaluated at a wind speed of 28 m/s. Parameters measured included: drag coefficient Cx, lift coefficient Cy, pitch moment coefficient Cm, center of pressure coefficient Cp, and the lift-drag ratio Cy/Cx, over a range of angle of attack (0°-70°). These coefficients were used in analyzing the differences in the performance among the three otter-board models. Results showed that the maximum lift coefficient Cy of the otter-board model with a main-panel angle of 0° was highest (1.875 at α = 25°). However, when the angle of attack was smaller (0 < α < 22.5°), the lift coefficient of the otter-board increased as the angle of the main-panel increased. The maximum Cy/Cx of the otter-board with a main-panel angle of 12° was highest (7.417 at α = 2.5°), and the lift-drag ratio increased when the angle of the main-panel increased within the angle of attack at small angles (0 < α < 12.5°). A comparative analysis of Cm and Cp showed that the stability of the otter-board with a main-panel angle of 0° is better than those of the other models. Therefore, the comparative analysis of Cm and Cp, shows that a larger angle of the main-panel can reduce the stability of single-slotted otter-board. The findings of this study offer useful reference data for the structural optimization of otter-boards for trawling.