Hubrid Hull Forms and Drag Reduction for Conceptual High Speed Submersibles

Department of Defense is interested in development of small fighter-like vehicle for combined underwater and surface motions at high speeds. The vehicle requires carry weapons under water. The weapons may generate high additional drag, and drag reductionis the key aspect in design of its hybrid hull. Hydrofoil removes missiles from water at highest speeds, but the problem is to reduce the drag before take off.Our firm proposed to hold weapons within specially generated partial low-drag cavities under the top hydrofoil of a frame-biplane located between the center hull and the struts jointed to side hulls. Phase I has proven possibility hydrofoil drag reductionby partial cavitation with employment of suggested CFD tools for hydrofoil design.Phase II is assigned to find by employment of such CFD tools and experimentally validate: (1) Maximum of possible drag reduction for hydrofoil (with possible increasing of cavity length); (2) Effects of cross-flow on performances of designed low-dragpartially cavitating hydrofoils; (3) Possibility to stabilize low drag of these hydrofoils under sea-induced unsteady perturbations of by developed active flow control systems. A vehicle model towing tank test will be performed to verify model dragreduction by partial cavitation.