In-Situ and Temporary Augmentation of Ship Hull Forms to Improve Top Speed

U.S. Navy intends to modify transport craft hull forms in-situ in order to reduce hull hydrodynamic drag down to level that allows the 30% increase of their top speed. The project is emphasized on the craft LCU 1600. For such increase, designers must cut roughly a half of the craft total drag. This would require reduce both friction and wave resistance. Mechmath LLC plans achieve the friction reduction by generation of ventilated partial cavities on the craft bottom. Cavitation reduces friction by separating water from a part of the hull, but usually there is a significant drag penalty to create a cavity. This penalty takes place because of flow pulsations caused by reentrant jet in the cavity tail. The pressure gradients generated by specially designed appendages can suppress such jets. Their design will be based on solving nonlinear inverse hydrodynamic problem, but constrains associated with appendage removal and implementation will be imposed on the obtained solutions. Consideration of possible reduction of wave resistance with removable bulbs will also be done. A part of Phase I work consists of planning the Phase II experiments that must be provided with keeping the Froude numbers and cavitation numbers.