Optimisation of Double Floating Bodies for Small Unmanned Marine Devices Based on a New Hydraulic Flexible WEMP System

Abstract

Low-power, small-size, unoccupied devices are often used in the ocean. However, the requirements for long-distance operation and long-term, high-power supplies have always been difficult technical problems to solve. Wave energy can be effectively used to meet the requirements of a high power supply. Based on a comprehensive analysis of the shortcomings of existing wave energy converters, we present an innovative design for a novel hydraulic flexible wave energy mobile power system and its internal structure. The dynamic model is then simplified into a double-float system, with a spring force from a flexible liquid bag on the upper and lower floating bodies. Furthermore, a model is developed to assess the energy efficiency of the double floating body, and the energy supply strategy and the posture of the double-float system are investigated. The hydrodynamic parameters of three typical axisymmetric rotary floating bodies are analysed using AQWA software, and it is found that the hemispheric-bottomed cylinder (HBC) exhibits superior energy efficiency under the same conditions of space, mass, and drainage volume. Its energy efficiency is mainly reflected in its ability to capture the wave frequency and wave width. HBC floaters perform optimally in both respects. The stability of our design is analysed, and a mathematical relationship between the centroid G and the centre O of the HBC model is developed. The stability of the model is then studied. This study provides a theoretical basis for the provision of low-power, compact, unmanned maritime equipment.

Keywords

• double floating body system
• wave power supply
• flexible liquid capsule
• mobile power
• unoccupied ocean devices