Design and Experimental Identification of the Main Hydrodynamic Parameters for an Open-Frame ROV to the Peruvian Scallops Stock Assessment

Abstract

Abstract This work presents the design and the experimental methods to identify the main hydrodynamic parameters for an open-frame underwater vehicle for the stock assessment of the Peruvian scallops. The added mass was determined from free oscillation tests in the surge, sway and heave directions with the reduced prototype model submerged in water and supported by springs. The acceleration data collected during the oscillations demonstrated that the equation of damped natural frequency gave a better approximation of added mass because of the fluid damping. The drag parameters in the directions of surge, sway, and heave were determined by two experimental methods in which the prototype was moved with constant velocities. In the first method, the prototype moved attached to a towing carriage through a water channel, and the second method consisted of applying different forces using the vehicle's thrusters that let it move. In both methods, the vehicle's velocity and force were known. The data collected led to determine the linear and quadratic drag parameters using the least square method. The results of the self-propelled tests were slightly different from those obtained in the towing tank because the thrust was not measured with the thruster installed in the prototype, being this in motion, confirming the importance of quantifying the interactions thruster- thruster and thruster-frame and the loss of force due to the vehicle's motion.