| 摘要 |
PROBLEM TO BE SOLVED: To provide a propeller capable of achieving a high lift coefficient. SOLUTION: This propeller including one or multiple blades fitted to a shaft to be different in center generates free vortex in a fluid by dynamically changing a blade pitch. In the case of fetching energy of a moving fluid, while a fluid flow working on the blade rotates the propeller, a pitch change produces a fluid flow pattern known as Karman vortex street. The time average flow field resulting away from the propeller is a trailing field, and the energy of a fluid flow can be efficiently converted to the rotation of a shaft driving device. In the case of propulsion, the given shaft rotation and the dynamic pitch change in the fluid are joined to produce a flow pattern reverse to Karman vortex street. The propeller is suitable especially for a low flow velocity in terms of utilization of energy or propulsion. In the low flow velocity, owing to an effect of separation of flow caused by a low Reynolds number on the blade, it is inefficient in the other propeller. COPYRIGHT: (C)2007,JPO&INPIT
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