Session: 06-12-02 Ship Hydromechanics II

Paper Number: 80248

80248 - Kinetic Characteristics and Hydrodynamic Forces on Semi-Planing Typed High-Speed Vehicle by Model Test and RANS Simulation 

This paper aims to understand the kinetic characteristics and the hydrodynamic forces on a semi-planing typed high-speed vehicle during moving straight in calm water and in waves. The authors have been developing a simulator for evaluating the maneuverability, safety, and mobility of various vehicles under diverse environment, on the land, water including shallow water. The motion calculation of vehicles in this simulator is based on MMG (Maneuvering Mathematical Modeling Group) model which is a mathematical model for ship maneuvering motion proposed in Japan.

This study focuses on semi-planing typed high-speed vehicles. The semi-planing typed high-speed vehicle targeted in this study has a box-shaped hull with a flat bottom and flaps on the front and the rear part of the hull, which utilizes the lift force acting on the bottom and the flaps for decreasing the submerged volume and the wetted surface area to achieve high water speed. One of the features of this vehicle is considerable variation in its attitude due to the changes in the resistance value and propulsion performance associated with the change in the water speed of the vehicle, and no reliable method has been established to evaluate this feature in advance. Therefore, the authors conducted free towing tests using a scale model of the vehicle with free heaving and pitching to understand the equilibrium attitude and the kinetic characteristics of the model in calm water and in waves. As a result, the mean values and the variation amount of the equilibrium attitude and the hydrodynamic force corresponding to the Froude number of 0.03-1.8 were obtained. On the basis of the above results, we measured the hydrodynamic forces in a wide range covering the equilibrium attitude of the model by captive towing tests in calm water. The results show that the vehicle can move straight stably without unstable vibration even at high water speed. In addition, the authors performed 3D unsteady RANS (Reynolds-Averaged Navier-Stokes equation) simulation for the vehicle with the Froude number of 1.8 in calm water and found that the experimental result can be relatively well reproduced with respect to the vehicle’s attitude, the drag coefficient, and the free surface shape around the vehicle.

Considering the actual operation of the vehicle at sea, future work on its maneuverability and shallow water effect is needed to establish our simulator. Furthermore, since the increase in the exposure of the vehicle to the air increases the influence of the wind on the vehicle, it is important to evaluate the wind load when moving at high water speed in the future.

Presenting Author: Kenta Hasegawa National Maritime Research Institute, National Institute of Maritime, Port and Aviation Technology

Authors:

Kenta Hasegawa National Maritime Research Institute, National Institute of Maritime, Port and Aviation Technology
Motoki Araki National Maritime Research Institute, National Institute of Maritime, Port and Aviation Technology
Kei Ishida National Maritime Research Institute, National Institute of Maritime, Port and Aviation Technology
Kazuhiro Yukawa National Maritime Research Institute, National Institute of Maritime, Port and Aviation Technology
Shota Saito Ground Systems Research Center, Acquisition, Technology & Logistics Agency, Ministry of Defense
Ryoya Sano Ground Systems Research Center, Acquisition, Technology & Logistics Agency, Ministry of Defense
Keisuke Uemura Ground Systems Research Center, Acquisition, Technology & Logistics Agency, Ministry of Defense