Numerical analysis has been carried out to analyze seawater flow field and power generation characteristics of the tidal current power generation system for various multi channel shroud systems. Geometrical multi channel arrangement largely affects the flow field characteristics in the shroud system which power generation performance through turbine blade depends on. Sectional averaged velocity in front of the turbine blade which increases more than 2 times compared with channel inlet is much influenced as well as the flow from the rear with curl. And flow variation results in high inlet velocity in horizontal arrangements of multi channels with mechanical output of the turbine. These results are expected to be used as applicable data for the development of the tidal power generation system with shrouds.

Numerical analysis has been carried out to investigate seawater flow field characteristics with various current directions near the manganese nodule mining device. Seawater flow near the collecting device is largely influenced by the sea current direction, especially along the downstream of the rear system. Predicted flow velocity distributions are analyzed with turbulent kinetic energy and drag force. There is big flow field variation when the direction angle between the mining device and seawater current flow approaches to 30°~ 120°, and flow velocity along the rear region of 60° becomes faster than 180°. Averaged turbulent kinetic energy at 180° also becomes low, about 57% higher at 60°. These results from the study can be applicable to the optimum design of manganese nodule collecting system in the deep seawater flow.

Numerical simulation has been carried out to analyze seawater flow characteristics for shroud geometry variations with tidal current generation turbine. Seawater flow field characteristics in the turbine system are largely influenced by the shroud geometry. The vortex flow area in the diffuser part of the shroud gradually grows with the increase of shroud angle, but its recirculation velocity gets smaller. The centerline velocity of shroud increases with the length of cylinder part when diffuser part length and angle are constant(2.5m, 0.733rad) for the cylinder-diffuser type shroud system. Seawater velocity on the tip of turbine blade is pretty high, and as radial distance increases from the turbine axis, there is more gap between the fluid velocity isolines. These results in this study will be applicable for optimal design of tidal current generation system.