Hydrodynamic characteristics of a hyper-lift otter board with wing-end plates

Abstract

The paper investigates the hydrodynamic characteristics of a hyper-lift trawl door (HLTD), which consists of a cambered plate with two wing-end plates with the leading edge modified into an airfoil shape. Flume experiments were carried out in a circulating water tank using models having a wing area of 625 cm2 and an aspect ratio of 1.0 at camber ratios of 15, 20, and 25 %. To determine the effect of the wing-end plates, models with different size of wing-end plates were tested. Moreover, the effect of heel angle on the hydrodynamic characteristics of the HLTD was also investigated. We concluded that the size of the wing-end plate was significant for h/c = 0.10 (h width of the wing-end plate, c chord length of cambered plate), and the maximum lift coefficients of HLTDs with camber ratios of 15, 20 and 25 % were 2.19, 2.38, and 2.48, respectively, at an attack of angle of 38°. In addition, our findings showed that the effect of the heel angle was very small on the lift, drag and moment coefficients of a HLTD when it slants at heel angles from −20° to 20° during trawling.