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.
In this study, natural frequency characteristics of road mower head system are investigated through experiment and numerical analysis. ANSYS workbench 14.5 is used to calculate the frequency analysis in the mower system. Compared the natural frequency using the modal test and computerized analysis. When compared with the experimental results, a 5% error rate has occurred. Simulation results showed that vibration mode shape has directional characteristics, especially to the right and left. These results will be helpful in optimal design for road mower head systems.
Seawater flow characteristics around deep-sea sediment resuspension system was analyzed using CFD simulation. Seawater flow is influenced by migration velocity of DSSRS and the resuspension system with disturbance device. Especially complicated flow field is generated with discharged flow in the vertical direction, and there is large variation of seawater velocity near the system with vortex flow. Turbulent kinetic energy near the system increases 2～6 times, and its variation is also affected by the operation condition of the disturbance device. The results of this study are expected to be useful in evaluating the environmental effects of the suspended solid matters which are generated in the deep sea sediment disturbance process.
Numerical analysis was performed to analysis the structural characteristics of the head device in the road mower system. The head device connects mower system with the boom of the special vehicle. The system with various road surface conditions is subjected to continuous vibration and repeated load. Especially, the maximum equivalent stress occurs in the pillar of the head device, and the maximum equivalent strain also occurs in the fixed plate that supports the mower system. Fatigue analysis results show that the upper end of the pillar is very vulnerable. This analysis results can be used as basic data for optimal road mower head system design.
CFD(Computational Fluid Dynamics) analysis was carried out to analysis the air flow characteristics of vertical axis wind turbine system with accelerating device. Geometric arc angle of the accelerating device affects the air flow characteristics in the turbine with the effect of Coanda generated from the curved surface. Air velocity distributions with the device angle variation are compared. Flow velocity increases with the device length, and the accelerating device plays a key role in decreasing the air velocity in the wake flow region. Maximum air velocity variation becomes reduced with the accelerating device, and it is largely affected by the arc angle. These results are expected to be utilized in various ways to determine the shape of accelerating device for wind power generation system.
The characteristics of temperature variation for laser diode welding system have been analyzed with numerical investigation. The laser diode is assembled with a cap and stem by projection welding. Resistance heat, in this process, is generated by electric current at the contact surface between cap and stem within a very short time. Temperature variation of laser diode is largely affected by the welding time and the heat generated from the surface. Maximum temperature of each component in the laser diode should be lower than the melting point except for cap and stem in order to prevent welding defect. Temperature distribution of each component in the laser diode is also affected by thermal conduction mechanism. Welding defect near the insulator occurs when the resistance heat is high. Appropriate resistance heat supply to the laser diode was about 400W. The results from this study could be applicable for optimal design of laser diode welding system.
In this study, center marking process is numerically analyzed to investigate the characteristics of deformation of aluminium alloy bracket by the pin load. The proper size of groove which are required for marking system and the pressure of cylinder are predicted through the analyse of stress and strain fields of the plate. The results of this study show that von Mises stress is a maximum when the maximum of reaction force.
In this study, temperature variation characteristics in the stone board cutting device with sheath heater were analyzed through numerical investigation. Four 2kW sheath heaters whose length and diameter are 1800mm, 11mm are installed, and the initial temperature is -5℃. Also Transient condition is used for temperature variations with the operating time of sheath heater. From the analysis, transient temperature variations of cutting device after operating the sheath heater were predicted. Temperature variations were predicted that mainly appears in part contacted with the sheath heater. The result will be helpful in optimal design for various system equipped with sheath heater.