Hydrodynamic Force calculation over an axisymmetric auv with constant ocean currents at large range of angles of attack

Abstract

[EN] Mobile robotics has allowed remote exploration of terrestrial, aerial and aquatic environments; environments that present conditions where human could not bear; e.g., extreme temperatures, extremely low or high-pressure and perform surveillance without being detected among others. The incorporation of robots in these activities reduces the risk to which a human would be exposed in these environments. In aquatic environments, specifically in ocean, there are currents that interfere in the development of missions such as data acquisition and structures overhaul, these streams affect robot activities making difficult to maintain a specific position to develop the mission accurately. The application of a control strategy that allows keeping the robot in a specific position requires of the Hydrodynamic Force generated by the marine currents. On the other hand, as the robot moves it is necessary to know the magnitude of the Hydrodynamic Force changes in the new positions. This work was performed on a symmetric Autonomous Underwater Vehicle (AUV) Hull in the X-Y and X-Z planes in a range of attack angles from 0o to 180º. In this article, a series of simulations was developed through Computer Fluid Dynamics (CFD). This method allowed to observe three zones in the graph of the hydrodynamic coefficient (CH) according to the angle of attack (0o ¿ ¿ ¿ 25º, 20o < ¿ ¿ 90º y 90o < ¿ ¿ 180º), for each of these zones a correlation was proposed empirical polynomial of third order to obtain the magnitude of the Hydrodynamic Force (fH). The simulations were performed for a Reynolds number of 1.8 x 106 , based on the diameter of the Hull. This methodology is proposed as a solution to evaluate in an agile and satisfactory way the Hydrodynamic Force for different orientations between the vehicle studied and the flow.