Study of board bending degree on hydrodynamic performances of a single-layer cambered otter-board

Lei Wang,Lu Min Wang,Wen Wen Yu,Yong Li Liu,Yong Jin Wang,Xun Zhang,Rong Jun Zhang,Guang Rui Qi,Z.B Xu,J.Y Liu,D.Q Chen

doi:10.1051/e3sconf/201913101120

Abstract

The effect of board bending degree on hydrodynamic performances of a single-layer cambered otter-board was investigated using engineering models in a wind tunnel. Three different bending degree boards 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 , over a range of angle of attack (0° to 70°). These coefficients were used in analyzing the differences in the performance among the three otter-board models. Results showed that the bending of the board(No. 2, No. 3) increased the water resistance of the otter-board, and improved the lift coefficient of the otter-board in the small angle of attack (0°<α≤20 °) ; the maximum lift coefficients Cy of otter-board model (No. 1) was higher (1.680, α = 25°). the maximum lift–drag ratios of models (No. 1, No. 2 and No. 3) are 6.822 (α = 7.5 °), 6.533 (α = 2.5 °) and 6.384 (α = 5.0°), which showed that the board bending reduces the lift-to-drag ratio of the otter-board.The stability of the No. 3 model was better than those two models (No. 1, No. 2) in most range of attack angle, but No. 1 otter-board model had a better stability in roll of otter-board. The findings of this study can offer useful reference data for the structural optimization of otter-boards for trawling.

Highlights

The merits of the hydrodynamic performance of otterboard what is the important part of fishing gear for spreading the trawl mouth can be measured on the basis of the lift coefficient of the otter-board, the drag coefficient of the otter-board, the pitching moment coefficient, and the center of pressure coefficient of the otter-board [1]
We describe an experiment using otter-board models (n=3 designs) in a wind tunnel in which we measured various hydrodynamic coefficients for a range of angles of attack
The lift– drag ratio was computed (Cy / Cx), which is an important factor for determining the merits of the hydrodynamic performance of otter-boards

Summary

Introduction

The merits of the hydrodynamic performance of otterboard what is the important part of fishing gear for spreading the trawl mouth can be measured on the basis of the lift coefficient of the otter-board, the drag coefficient of the otter-board, the pitching moment coefficient, and the center of pressure coefficient of the otter-board [1]. Optimizing the structure of otter-boards may improve the hydrodynamic performance of the otter-board [2-13]. Improvements in the hydrodynamic performance of otter-boards has become a major research interest as the development of offshore trawler fleets increasing globally in recent decades. The following study investigates the importance of the board bending degree within the otter-board. We describe an experiment using otter-board models (n=3 designs) in a wind tunnel in which we measured various hydrodynamic coefficients for a range of angles of attack. The results are relevant as a reference for the study of the structural parameters of the board bending degree of otter-boards

Methods

Results

Conclusion