Abstract
The authors have invented a unique counter-rotating type tidal stream power unit composed of tandem propellers and a double rotational armature type peculiar generator without the traditional stator. The front and the rear propellers counter-drive the inner and the outer armatures of the peculiar generator, respectively. The unit has the fruitful advantages that not only the output is sufficiently higher, but also the rotational moment hardly act on the pillar because the rotational torque of both propellers/armatures are counter-balanced in the unit. This paper discusses experimentally the performances of the power unit and the effects of the propeller rotation on the force acting on the pillar. The axial force acting on the pillar increases with the increase of not only the stream velocity but also the drag of the tandem propellers.
