Abstract
In the case of using the resistance-type virticai-axis wind rotors as a water wheel, the Savonious rotor shows the worst efficinsy. Then in this paper, the reason of these experimental results is tried to investigate by visualizing flow fields around rotors without a rotation. In the visualization, the smoke of Japanese short piece is used for the reason that the continual time is comparatively long and the smoke is thick. The sharp pictures are obtained and it can be thought from these pictures that the factors affected on the efficiency are not only the flow blown throuth between the blades but also the disturbances created behind the rotors.
