To study the effectiveness of stern appendages (Cruciform & X Shaped configurations) for maneuverability of autonomous underwater vessel using computational fluid dynamics

Abstract

Maneuverability is one of the main aspects to be considered during the early design stage of Autonomous Underwater Vehicles. Several captive tests such as Planar Motion Mechanism (PMM), Oblique towing test, and Rotating Arm tests were conducted to obtain the hydrodynamic derivatives of the Autonomous Underwater Vehicle (AUV). In this research, the effectiveness of control surfaces with Cruciform and X configurations has been predicted for the maneuverability of the DARPA SUBOFF model. Computational Fluid Dynamics (CFD) technique was applied and the k- ω turbulence model was used to estimate the flow characteristics in the boundary layer region. The Straight-Line Towing Tank test has been used to calculate the hydrodynamic derivatives due to linear velocity, while the Rotating Arm test with a moving reference frame has been used to estimate the hydrodynamic derivatives. All the tests were conducted at a speed of 6.5 knots and three angles of incidence (10,30,50) for Straight-Line motion and three radii (13m,18m,24m) for Rotating Arm test were adopted. The simulation results of hydrodynamic coefficients have been compared with experimental results for the Cruciform configuration and the error was below 15%. So, the same procedure was adopted for the X-form configuration, and the stability index was calculated for both configurations.