• International Journal of Naval Architecture and Ocean Engineering
• /
• v.9 no.1
• /
• pp.55-65
• /
• 2017

Underwater torpedo has control fin with very low aspect ratio due to launching from limited size of cylindrical torpedo tube. If the aspect ratio of control fin of underwater vehicle is very low three-dimensional flow around control fin largely reduces control forces. In this study, the end plate was applied to reduce the three-dimensional flow effects of partially movable control fin of underwater vehicle. Through numerical simulations the flow field around control fin was examined with and without end plate for different flap angles. The pressure, vorticity, lift and torque on the control fin were analyzed and compared to experiments. The comparison have shown a reasonable agreement between numerical and experimental results and the effect of end plate on a low aspect ratio control fin. When the end plate was attached to the movable control fin, the lift increased and the actuator shaft torque did not significantly change. As this means less consumption of the actuator shaft torque compared to the control fin that has the same control force, the inner actuator capacity can be reduced and energy consumption can be saved. Considering this, it is expected to be effectively applied to the control fin design of underwater vehicles such as torpedoes.

• Journal of the Society of Naval Architects of Korea
• /
• v.37 no.3
• /
• pp.57-68
• /
• 2000

The Power Augmented Ram(PAR) effect, which blows the down stream of the propellers into the underside of the wings and hence increases the pressure between the lower surface of the wings and the sea surface, is known significantly to enhance the performance of the WIG concept by reducing the take-off and landing speeds. The aerodynamic characteristics of a 20 passenger PARWIG are investigated by wind tunnel tests with the 1/20 scale model. The efflux of the forward mounted propellers are simulated by jet flows with a blower and duct system. The lift, drag, and pitch moment of the model with various ground clearances, angles of attack and flap angles are measured for the various jet velocities, jet nozzle angles, horizontal and vertical positions of the nozzle, and the nozzle diameters. The aerodynamic characteristics of the PARWIG due to these parametric changes are compared and pertinent discussions are included. It is shown that the proper use of the PAR can increase the lift coefficient of as much as up to 4.