A paddle wheel is a form of waterwheel or

impeller An impeller or impellor is a rotor used to increase the pressure and flow of a fluid. It is the opposite of a turbine, which extracts energy from, and reduces the pressure of, a flowing fluid. In pumps An impeller is a rotating componen ...

in which a number of paddles are set around the periphery of the wheel. It has several uses, of which some are: * Very low-lift

water pump A pump is a device that moves fluids (liquids or gases), or sometimes slurries, by mechanical action, typically converted from electrical energy into hydraulic energy. Pumps can be classified into three major groups according to the method they ...

ing, such as flooding paddy fields at no more than about height above the water source. * To move and mix algae culture in the raceway ponds used for

algaculture Algaculture is a form of aquaculture involving the farming of species of algae. The majority of algae that are intentionally cultivated fall into the category of microalgae (also referred to as phytoplankton, microphytes, or planktonic algae). Mac ...

. * Propulsion of watercraft (as a paddlewheel) * Low head hydro power (as a waterwheel) * Flow sensors * Aerators The paddle wheel is an ancient invention but is still used today in a wide range of industrial and agriculture applications.

Ship propulsion

Paddle wheels would enable ships to travel without needing wind or oars. They were made obsolete by

propellers A propeller (colloquially often called a screw if on a ship or an airscrew if on an aircraft) is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon ...

, which had greater propulsion with lower weight and fuel usage. This was demonstrated by an 1845 tug-of-war competition between and with the screw-driven ''Rattler'' pulling the paddle steamer ''Alecto'' backward at .Propeller versus Paddle: The Tug of War between HMS Rattler and the Alecto
Bow Creek to Anatahan.

Physics

The paddle wheel is a device for converting between

rotary motion Rotation around a fixed axis is a special case of rotational motion. The fixed-axis hypothesis excludes the possibility of an axis changing its orientation and cannot describe such phenomena as wobbling or precession. According to Euler's rot ...

of a shaft and

linear motion Linear motion, also called rectilinear motion, is one-dimensional motion along a straight line, and can therefore be described mathematically using only one spatial dimension. The linear motion can be of two types: uniform linear motion, with co ...

of a fluid. In the linear-to-rotary direction, it is placed in a fluid stream to convert the linear motion of the fluid into rotation of the wheel. Such a rotation can be used as a source of power, or as an indication of the speed of flow. In the rotary-to-linear direction, it is driven by a

prime mover Prime mover may refer to: Philosophy *Unmoved mover, a concept in Aristotle's writings Engineering * Prime mover (engine), motor, a machine that converts various other forms of energy (chemical, electrical, fluid pressure/flow, etc) into energy ...

such as an

electric motor An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate for ...

or steam engine and used to pump a fluid or propel a vehicle such as a paddle-wheel steamer or a steamship.

References

{{reflist Watermills Pumps