Nonlinear dynamics of towed underwater vehicles - numerical modelling and experimental validation

摘要

Controllable towed underwater vehicles are used as carrier systems in a wide range of maritime applications. The quality and accuracy of the registered multimedia seabed and subsoil data depends on the dynamic behaviour and stability of the towed sensor carrier as well as on the transmission of wave induced motions along the submarine umbilical. This paper presents a comprehensive numerical and experimental analysis of the dynamic behaviour of towed systems, taking into account the nonlinear characteristics of drag and lift coefficients as well as the non-linear dynamic cable force. It is proved that ship motions are inducing substantial cable oscillations resulting in significant excitation of the towed body. A computer program is developed to determine the cable curvature for stationary conditions as well as the dynamic response of the towed body due to ship oscillations. The numerical model is validated by towing tests, performed at the TU Berlin in one of the world largest cavitation and circulation tunnels with free surface.