要素移動モデルを用いた潮流発電用相反転方式プロペラの流体解析

抄録

Tidal stream power generation as renewable energy is one of the energy-source candidates for realizing sustainable society. Counter-rotating-type propellers are utilized in the conversion of tidal stream kinetic energy to electric energy. In this type of propeller, the rotational torques of the front and rear propeller are counter-balanced, thus they have no reaction force. This feature enables to moor a power unit with a cable from a floating or sea-bed base. The posture and performance of a moored power unit is easily affected by tidal stream condition. To evaluate precisely the performance in such power unit, unsteady flow simulation using a propeller rotating model is studied. As a first step, the flow simulations were carried out under the condition that the power unit axis was aligned with the flow direction. Moving element model was employed as a propeller rotating model. At first, the grid convergence in the simulations was confirmed. Second, the rotational speeds of the front and rear propeller under the torque equilibrium were examined. Finally, the power coefficient was evaluated at various rotational speeds. The output ratios were calculated from the obtained power coefficients and were compared with Lee’s wind tunnel test results. The numerical output ratios almost agreed with the experimental ones.