Design Procedures for Low Speed Waterjets Suitable for Application in Amphibious Vehicles

摘要

The U.S. Marine Corps is supporting an effort to increase the efficiency of waterjet propulsion units in existing amphibious vehicles. A previous report details the design of three axial-flow pumps, including one for an existing LVTP-7A1 which runs at speeds below 8 miles per hour. The other two pumps were designed to provide cavitation-free performance at propulsive coefficients in the region of 40-45% at a vehicle water speed of 20 mph. State-of-the art composite material technology was used wherever possible to reduce weight. Next, a manned testcraft was constructed to evaluate a 14-in diameter waterjet unit at vehicle speeds up to 25 mph in water. Trials performance of an axial flow pump, used for waterjet propulsion in a manned testcraft, was analyzed, compared to design predictions, and then used to modify pump design procedures as appropriate. Performance estimates have been made for a new waterjet unit for the testcraft, and also for a larger unit which could be used in a prototype high-speed amphibious vehicle.