Improving the efficiency of the trawl fishing system by improving hydrodynamic quality of flexible trawl kites
The catchability of the trawl is ensured by its design, the speed of trawling, horizontal and vertical opening of the mouth of the trawl. Vertical opening is provided by equipping the headline with hydrodynamic kites, the lower one with loading. The problems of increasing the efficiency of the trawl system by providing the necessary opening of the mouth of the trawl with the help of lifting hydrodynamic means - a flexible trawl kites are considered. The improvement of the design of the trawl kite should be aimed at improving its hydrodynamic quality - reducing the resistance to movement and increasing the lifting force, which should ensure the opening of the mouth of the trawl by lifting the upper pick-up. Since it is difficult to conduct full-scale tests, the shield model was tested in the experimental pool while ensuring kinematic and dynamic similarity of the model and full-scale shield. Experimental work carried out in an experimental pool with models of kites made it possible to improve experimental equipment, in which refined hydrodynamic coefficients Cx and Cz were obtained depending on the angles of the flap in the water flow. In addition, a new design of the trawl shield has been developed, for which it is necessary to determine the hydrodynamic characteristics. The increase in hydrodynamic quality is achieved by the fact that the flexible plate is made with an air cavity along the entire leading edge. In this paper, the results of testing models of kites are presented, a range of angles of attack at which the lifting force takes maximum values is obtained, as well as a range of angles at which the greatest hydrodynamic quality of flaps is observed. It is necessary to continue experimental work with the experimental shield and compare the obtained coefficients Cx and Cz with the data of the trawl kite.