流れ場に応じて独立に回転する2台のサボニウス型回転装置周りの流れの数値シミュレーション

抄録

In this study, we investigate the flows around two Savonius turbines that rotate independently by numerical simulation considering the application to ocean current power generation. In general, when analyzing the flow around a rotating object, a rotational coordinate system is often used. However, it is difficult to calculate with such coordinate system when two objects rotate in the reverse direction independently. Therefore, we use the overset grid that consists of two rotational coordinates for each turbine immersed in a steady coordinate to calculate this turbines’ system. The basic equations are the incompressible Navier-Stokes equations expressed by the both rotational and steady coordinate systems. The nonlinear terms of the basic equations are approximated by the third order upwind difference in order to perform stable calculations even at high Reynolds number. The fractional step method is employed to solve the basic equations. In this study, the torque acting on the device is calculated from the flow field, and the equation of motion of rotation is solved using the torque, and the flow is simulated even when the rotation speed changes with time.