IMPELLER
An impeller is a mechanical device involving curved concentrically arranged blades that function by rotating around an axis to which they are attached in order to convert the gravitational and kinetic energy of moving fluids, such as water and air, into other forms of energy.
Affixed in various numbers to a shaft or rotor, an impeller may look identical to a propeller, but a propeller employs an internal source of energy (as in prop driven aircraft or nuclear submarine) to propel an attached object through a fluid that is discharged behind it. By contrast, impellers in hydroelectic plants simply rotate on a shaft by resisting the direct gravitational descent of water that would otherwise make a waterfall.
Similarly, a wind turbine does not have a propeller, but an impeller. Since the relative motion (of fluids past the blades) is independent of end use, it would be theoretically possible to place a powerful engine inside a cowling affixed to the wind turbine and, on a windless day, propel it free of its pylon. The force generated by reversing the intended use would, as in submarines, be all backward, with no upward component. Read More
An impeller is a mechanical device involving curved concentrically arranged blades that function by rotating around an axis to which they are attached in order to convert the gravitational and kinetic energy of moving fluids, such as water and air, into other forms of energy.
Affixed in various numbers to a shaft or rotor, an impeller may look identical to a propeller, but a propeller employs an internal source of energy (as in prop driven aircraft or nuclear submarine) to propel an attached object through a fluid that is discharged behind it. By contrast, impellers in hydroelectic plants simply rotate on a shaft by resisting the direct gravitational descent of water that would otherwise make a waterfall.
Similarly, a wind turbine does not have a propeller, but an impeller. Since the relative motion (of fluids past the blades) is independent of end use, it would be theoretically possible to place a powerful engine inside a cowling affixed to the wind turbine and, on a windless day, propel it free of its pylon. The force generated by reversing the intended use would, as in submarines, be all backward, with no upward component. Read More