September 23, 2013
Dr. Len Imas of the Department of Civil, Environmental and Ocean Engineering at Stevens Institute of Technology has been awarded a grant from the Office of Naval Research (ONR) for the investigation of ultra-deep vee planing hull hydrodynamics. This research will entail numerical simulation and comparison of computational results to measurement from full-scale sea trials to improve the understanding of the fluid dynamics of planing boats with an ultra-deep vee hull, which provides strong riding and handling capabilities in a sea-way.
“The engineering of more agile and efficient hulls can provide tremendous advantages for Navy and civilian vessels, giving them enhanced capabilities to maintain control at high speeds in severe conditions,” says Dr. Michael Bruno, Dean of the Charles V. Schaefer, Jr. School of Engineering and Science. “Continued innovation requires profound understanding of the various forces acting upon a ship in water, and experts in computational dynamics like Dr. Imas are providing transformative insights.”
Planing boats have hulls that take advantage of hydrodynamic lift. At low speeds, buoyancy is the dominant upward force opposing gravity that allows a vessel to float. Once a vessel with a planing hull achieves enough speed, the water pushes against it with a high enough pressure resulting in a force known as hydrodynamic lift. When such a lift force is the dominant upward force, the role buoyancy plays in keeping the hull afloat is reduced. As speeds increase, the vessel rises further in the water and minimizes resistance, enabling rapid and efficient travel through calm water. One problem with this design has been that a substantial seaway can make it difficult to maintain directional stability, so a planing boat may need to operate more slowly in rough conditions. The deep vee hull is a variation on this design with a wide, V-shaped rear converging at a forward point. This design helps balance the concerns of drag reduction and handling capability, with a front that “cuts” through the waves in order to maintain control and minimize drag, as well as a flatter rear section that enables planing.
Although the deep vee design has provided substantial benefits, it still has its disadvantages, one of which being that it takes more power from the engine to achieve planing. According to Dr. Alan Blumberg, Director of the Davidson Laboratory, “Researchers must improve the understanding of the relationship between hull geometry and the hydrodynamic behavior of ultra-deep vee hulls in order to help drive further design innovation. Dr. Imas’ methodology of combining computational hydrodynamics with data collected from prototype sea trials could be crucial to the improved understanding of fluid dynamics around unconventional high speed surface craft concepts based on this important design.”
Len Imas, Associate Professor of Ocean Engineering, holds a BS and MEng. in Aeronautical Engineering from Rensselaer Polytechnic Institute, and a PhD. in Numerical Hydrodynamics from Massachusetts Institute of Technology . His interests are in basic and applied research involving hydrodynamics and computational fluid mechanics related to topics ranging from nonlinear free-surface turbulent flows, to vortex induced vibrations, to high-speed surface and sub-surface marine vehicles, and to high-performance racing yachts. His specialization is in the development and utilization of computational fluid mechanics and optimization methods in design analysis applications involving marine hydrodynamics and low speed aerodynamics.
The Davidson Laboratory at Stevens was founded in 1935 and remains one of the world’s leading facilities for naval architecture research. The laboratory's renowned towing tank complex is 320 feet long, 16 feet wide and 8 feet deep. With recently upgraded instrumentation, glass walls for viewing and photography, and public access improvements, the facility is vital to the Laboratory's contributions to fundamental and applied research in ship design, hydrodynamics and ocean engineering.
About the Davidson Laboratory
The Davidson Laboratory at Stevens Institute of Technology works to preserve and secure U.S. maritime resources and assets through collaborative knowledge development, innovation and invention, and education and training. Composed of four integrated laboratory activities and three support groups, it has become the world’s leader in delivering new knowledge, advanced technology, and education in support of the maritime community. It uniquely integrates the fields of naval architecture, coastal and ocean engineering, physical oceanography, marine hydrodynamics and maritime security to create a trans-disciplinary enterprise that can address both the highly-specialized issues confronting each discipline, as well as the more complex, integrated issues facing natural and man-made maritime systems.
Learn More: http://www.stevens.edu/ses/cms/