FEASIBILITY STUDY AND HYDRODYNAMICS OF TRANSFORMABLE SUBMERSIBLE HYDROFOIL TRIMARAN

Abstract

It has been the endeavor of naval architects to design innovative hull forms to address the political, socio-economic climate and sustainability around the world. It is imperative that countries be able to protect their sea lanes and coastal zones from surveillance and infiltration from hostile foreign entities. Hence there is a need to develop radically different hull form, which possess the elusive ability and are capable of high-speed. In order to fulfill the idea, the hypothesis envisioned in this thesis is: the Transformable Submersible Hydrofoil Trimaran (TSHT) as an innovative and ground breaking hull form would address the feasibility of exhibiting low resistance and improved trim and sinkage characteristics when traversing on the surface and operate as a regular submarine underwater. This thesis attempts to illustrate a preliminary structural configuration, hydrofoil selection, and analysis along with numerical validation so as to address the hypothesis. The thesis attempts to illustrate the development of an innovative high-speed marine vehicle which can operate both undersea and on the surface. The vehicle is based on a patent “Body-variable three-body water wing combined diving boat” (CN104787275 B). The new vehicle (Transformable Submersible Hydrofoil Trimaran, TSHT) combines the characteristics of a submarine, hydrofoil craft, and trimaran. This paper will make a preliminary study of its feasibility addressing aspects such as surface resistance and undersea resistance. This paper will also compare these characteristics against data available from trimaran and mono-hull ship studies of similar displacement. Research at Florida Institute of Technology's Underwater Technology Laboratory is currently underway to implement a unified approach to develop autonomous systems that can remain underwater, navigate coastal regions, collect data, and selectively search for specific physical and chemical aspects observed in the coastal environment. The project undertaken in this thesis will attempt to carry out numerical simulations to determine the hydrodynamic characteristics of TSHT (490 t fully submerged). The simulations include the calm water resistance on the surface and undersea for Froude Numbers between 0.1 to 1.3 with different foil angles of attack and the trim and sinkage characteristics. Finally, the hypothesis illustrated earlier would be presented sequentially in various chapters so as to adequately address through numerous numerical and analytical procedures. The thesis successfully addresses the hypotheses in proving that resistance and power characteristics of TSHT are significantly lower than a comparable trimaran while traveling on the surface. Its resistance and power characteristics also show improvement over “SUBOFF” when compared with established methods and numerical simulation. Through numerical analysis, it has also been shown that TSHT has better trim and sinkage characteristics than a similar conventional trimaran. Thus it would be fair to state that the objectives of this thesis have been addressed and results show a high degree of confidence regarding the feasibility of such a hull form.