Experimental Hydrodynamic Parameters Identification for an Open Frame ROV used in the Stock Assessment of Scallops
This work addresses the experimental identification of the main hydrodynamic parameters of a remotely operated vehicle (ROV) used for the stock assessment of scallops on the north coast of Peru. The propulsion system, structural configuration, instrumentation, and communication system are described. The work is composed of four papers, three of which have already been published, and the last is the results obtained from the article sent to a scientific journal. The tests in the first article consisted of moving the ROV through a water channel with the vehicle attached to a towing carriage at constant velocities in surge, sway, and heave directions, considering one direction at a time. Then, the linear and quadratic drag coefficients were determined by the least square method. In the second article, the vehicle moved through a pool using its propulsion system. The vehicle individually moved in each of its degrees of freedom, surge, sway, heave, roll, pitch, and yaw at constant velocities. Afterward, the linear and quadratic drag coefficients were determined using the least square method. The third article determined the added masses in surge, sway, and heave directions through damped free oscillation tests in a water tank. The tests consisted of supporting a 1:3 scale model of the ROV in a fixed structure through springs and made it oscillate free and damply in still water in 1-DOF from different initial amplitudes and equivalent stiffnesses. Then, the added mass was determined using the damped natural frequency equation for a 1-DOF mass-spring-damper system. Finally, the fourth article determined the inertia and drag coefficients in the heave oscillatory motion of the ROV through free oscillation tests with springs. The least square method determined the hydrodynamic coefficients using the acceleration signal and three motion equations with different damping models. Then, the simulated response obtained with the Runge Kutta integration algorithm was compared with the experimental response to find the damping model that better described the system. The Reynolds numbers range tested was between and and Keulegan Carpenter in the range of 0.5 to 2. The values of drag coefficients, added masses, and hydrodynamic coefficients obtained from the different experimental tests in this work were compared with those by other researchers using ROVs with open frames. The results were coherent, and the procedures followed for each experimental test were validated.