The movement of a radar platform in complex marine environment will affect the radar operational efficiency and personnel safety. In this paper, the structure of a semi-submersible radar platform is optimized based on its hydrodynamics to reduce the environment effect. The hydrodynamics of the semi-submersible radar platform was studied in the frequency domain using ANSYS Workbench software. The structure parameters were optimized to maximize the maneuverability of the platform. A detailed relationship between each hydrodynamic parameter and the wave frequency was established to supplement the hydrodynamic database. Because of the difference between the bow and stern of the buoy, the first-order wave excitation force and motion response of the platform will be different. The analysis results showed that the variation of the pitch motion of the platform was obvious. Lastly, the habitability of the semi-submersible radar platform was evaluated according to human physiological tolerance. In general, the optimized semi-submersible radar platform has better hydrodynamic performance.
Offshore platforms typically operate in harsh marine environments, subject to not only hydrostatic pressure, buoyancy and gravity, but also environmental loads such as wind, waves and currents (Wang, S., Cao, Y., Fu, Q., & Li, H., 2015). Many researches have been addressed structural optimization and hydrodynamic analysis of offshore platforms. Birk and Clauss et al. (2001) studied the heave response of a semi-submersible platform shape optimization scheme. They optimized the shape of the buoy by increasing the volume of the buoy part at the connection between the pillar and the buoy and reducing the volume in the middle of the buoy to reduce the heave motion excitation while keeping the displacement unchanged. The results showed that the hydrodynamic performance was improved. Cermelli et al. (2004) studied the structural optimization by adding a heave plate to the bottom of the platform column, which increased the additional mass and damping coefficient of the platform itself, thus greatly improving the performance of heave motion. Huang and Mansour (2007) designed an H-shaped buoy structure, which added connected auxiliary buoy between two buoys of the conventional semi-submersible platform. The results showed that the heave and pitch motion in the regular wave period were reduced obviously. Lai et al. (2013) used numerical simulation method to study the hydrodynamic performance of a new-type semi-submersible support. Deep-draft buoys structures were used to resist the wave forces on the floating offshore, while damping structures were used to enhance the stability of wind turbine and reduce the heave amplitude. It was showed that the designed semi-submersible platform had excellent hydrodynamic performance. Garrido-mendoza et al. (2014) proposed a new-type heave plate on the semi-submersible fan platform and calculated its additional mass parameters. They found that the heave response of the platform was effectively suppressed. Domala et al. (2014) used the numerical simulation method to explore the optimal parameters affecting the hydrodynamic response, such as the main scale and the structural layout of the platform. Wang et al. (2015) designed a new-type semi-submersible lifting platform with asymmetric buoy and no transverse brace. The platform was more efficient in conventional sea conditions, but due to the asymmetric buoy arrangement there were obvious heave-roll and heave-pitch coupling responses near the natural period of heave. Jiang et al. (2016) used HydroStar software to quantitatively analyze the influence of different shapes such as column, brace and buoy on the heave motion and average drift force of the semi-submersible platform. Wu et al. (2017) developed a simplified algorithm for evaluating the hydrodynamic performance of mobile offshore bases (MOBs) in the preliminary design stage based on the assumptions of no navigational velocity and only random and irregular wave forces at high sea states. This study provided significant support for the evaluation of the hydrodynamic performances of very large modular semi-submersible structures. Gao et al. (2018) conducted numerical and experimental studies on the hydrodynamic performance of a new multiple column platform (MCP) with a center column and middle pontoon. Numerical simulations were conducted in both the frequency and time domains based on three dimensional (3D) potential theory. Moreover, a comparative study on MCP and two conventional semi-submersibles were carried out by using numerical simulation. Goncalves et al. (2018) studied the effect of vortex motion caused by section shape and surface roughness on hydrodynamic performance by pool test.
