Towing Tank Model Tests for Propulsive Performance Analysis of a Waterjet-Propelled Amphibious Vehicle

Abstract

The present study concerns a series of model tests in a towing tank on waterjet propulsive performance. The test model was an armored vehicle consisting of a box-shaped hull, two waterjets, a bow flap, and a trim tab. As per the powering prediction procedure of high-speed vessels, resistance tests, waterjet system tests, and self-propulsion tests were performed. The Froude number based on the characteristic length and advance speed for the model tests ranged from .981 to 1.178. Bollard pull tests were also conducted to investigate the interaction between the hull and two installed waterjets and to validate the flow rate estimation. In the self-propulsion condition, the dry transom and nozzle end modification changed the interaction efficiency. The waterjet reduced the vehicle trim in the self-propulsion condition, owing to the nozzle exit flow onto the trim tab.