Paddle wheel

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A paddle wheel aereator used in an Indonesian shrimp pond Paddlewheel aerator.jpg
A paddle wheel aereator used in an Indonesian shrimp pond

A paddle wheel is a form of waterwheel or impeller in which a number of paddles are set around the periphery of the wheel. It has several uses, some of which are:

Contents

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 enabled ships to travel without needing wind or oars. They were made obsolete by propellers, which had greater propulsion with lower weight and fuel usage. This was demonstrated by a tug-of-war competition in 1845 between HMS Rattler and HMS Alecto with the screw-driven Rattler pulling the paddle steamer Alecto backward at 2.5 knots (4.6 km/h). [2]

Physics

The paddle wheel is a device for converting between rotary motion of a shaft and linear motion 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. This 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 such as an electric motor or steam engine and used to pump a fluid or propel a vehicle such as a paddle-wheel steamer or a steamship.

Related Research Articles

Pump Device that imparts energy to the fluids by mechanical action

A pump is a device that moves fluids, 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 use to move the fluid: direct lift, displacement, and gravity pumps.

Propeller Device that transmits rotational power into linear thrust on a fluid

A propeller, is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral, that, when rotated, exerts linear thrust upon a working fluid, such as water or air. Propellers are used to pump fluid through a pipe or duct, or to create thrust to propel a boat through water or an aircraft through air. The blades are specially shaped so that their rotational motion through the fluid causes a pressure difference between the two surfaces of the blade by Bernoulli's principle which exerts force on the fluid. Most marine propellers are screw propellers with helical blades rotating on a propeller shaft with an approximately horizontal axis.

Pelton wheel Type of turbine

The Pelton wheel or Pelton Turbine is an impulse-type water turbine invented by American inventor Lester Allan Pelton in the 1870s. The Pelton wheel extracts energy from the impulse of moving water, as opposed to water's dead weight like the traditional overshot water wheel. Many earlier variations of impulse turbines existed, but they were less efficient than Pelton's design. Water leaving those wheels typically still had high speed, carrying away much of the dynamic energy brought to the wheels. Pelton's paddle geometry was designed so that when the rim ran at half the speed of the water jet, the water left the wheel with very little speed; thus his design extracted almost all of the water's impulse energy—which made for a very efficient turbine.

Steam engine Heat engine that performs mechanical work using steam as its working fluid

A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a cylinder. This pushing force can be transformed, by a connecting rod and crank, into rotational force for work. The term "steam engine" is generally applied only to reciprocating engines as just described, not to the steam turbine. Steam engines are external combustion engines, where the working fluid is separated from the combustion products. The ideal thermodynamic cycle used to analyze this process is called the Rankine cycle. In general usage, the term steam engine can refer to either complete steam plants, such as railway steam locomotives and portable engines, or may refer to the piston or turbine machinery alone, as in the beam engine and stationary steam engine.

Turbine Rotary mechanical device that extracts energy from a fluid flow

A turbine is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. The work produced by a turbine can be used for generating electrical power when combined with a generator. A turbine is a turbomachine with at least one moving part called a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades so that they move and impart rotational energy to the rotor. Early turbine examples are windmills and waterwheels.

Watermill Structure that uses a water wheel or turbine

A watermill or water mill is a mill that uses hydropower. It is a structure that uses a water wheel or water turbine to drive a mechanical process such as milling (grinding), rolling, or hammering. Such processes are needed in the production of many material goods, including flour, lumber, paper, textiles, and many metal products. These watermills may comprise gristmills, sawmills, paper mills, textile mills, hammermills, trip hammering mills, rolling mills, wire drawing mills.

Water wheel Machine for converting the energy of flowing or falling water into useful forms of power

A water wheel is a machine for converting the energy of flowing or falling water into useful forms of power, often in a watermill. A water wheel consists of a wheel, with a number of blades or buckets arranged on the outside rim forming the driving car. Water wheels were still in commercial use well into the 20th century but they are no longer in common use. Uses included milling flour in gristmills, grinding wood into pulp for papermaking, hammering wrought iron, machining, ore crushing and pounding fibre for use in the manufacture of cloth.

Paddle steamer Steam-powered vessel propelled by paddle wheels

A paddle steamer is a steamship or steamboat powered by a steam engine that drives paddle wheels to propel the craft through the water. In antiquity, paddle wheelers followed the development of poles, oars and sails, where the first uses were wheelers driven by animals or humans.

Steam frigate Type of steam-powered warship

Steam frigates, the larger steam ships of the line and the smaller steam corvettes, steam sloops, steam gunboats and steam schooners, were steam-powered warships that were not meant to stand in the line of battle. The first such ships were paddle steamers. Later on the invention of screw propulsion enabled construction of steam-powered versions of the traditional ships of the line, frigates, corvettes, sloops and gunboats.

Fluid power

Fluid power is the use of fluids under pressure to generate, control, and transmit power. Fluid power is subdivided into hydraulics using a liquid such as mineral oil or water, and pneumatics using a gas such as air or other gases. Compressed-air and water-pressure systems were once used to transmit power from a central source to industrial users over extended geographic areas; fluid power systems today are usually within a single building or mobile machine.

Impeller Rotor used to increase (or decrease in case of turbines) the pressure and flow of a fluid or gas

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.

Turbomachinery

Turbomachinery, in mechanical engineering, describes machines that transfer energy between a rotor and a fluid, including both turbines and compressors. While a turbine transfers energy from a fluid to a rotor, a compressor transfers energy from a rotor to a fluid.

A swimming machine is a resistance swimming apparatus, often self-contained, enabling the swimmer to swim in place. This may be accomplished either by accelerating the water past the swimmer or by supporting the swimmer, either in water or on dry land. The first type, known as a countercurrent swimming machine, usually consists of a water tank at least twice as long and about one and a half times as wide as an average person with the limbs extended. The swimmer swims unrestrained against an adjustable stream of water set in motion by means of mechanical devices, such as jets, propellers or paddle wheels.

Reciprocating motion Repetitive back-and-forth linear motion

Reciprocating motion, also called reciprocation, is a repetitive up-and-down or back-and-forth linear motion. It is found in a wide range of mechanisms, including reciprocating engines and pumps. The two opposite motions that comprise a single reciprocation cycle are called strokes.

Hydraulic motor

A hydraulic motor is a mechanical actuator that converts hydraulic pressure and flow into torque and angular displacement (rotation). The hydraulic motor is the rotary counterpart of the hydraulic cylinder as a linear actuator. Most broadly, the category of devices called hydraulic motors has sometimes included those that run on hydropower but in today's terminology the name usually refers more specifically to motors that use hydraulic fluid as part of closed hydraulic circuits in modern hydraulic machinery.

Marine propulsion Systems for generating thrust for ships and boats on water

Marine propulsion is the mechanism or system used to generate thrust to move a ship or boat across water. While paddles and sails are still used on some smaller boats, most modern ships are propelled by mechanical systems consisting of an electric motor or engine turning a propeller, or less frequently, in pump-jets, an impeller. Marine engineering is the discipline concerned with the engineering design process of marine propulsion systems.

HMS <i>Rattler</i> (1843) Sloop of the Royal Navy

HMS Rattler was a 9-gun steam screw sloop of the Royal Navy, and one of the first British warship to be completed with screw propulsion. She was originally ordered as a paddle wheel 4-gun steam vessel from Sheerness Dockyard on 12 March 1841. She was reordered on 24 February 1842 as a propeller type 9-gun sloop from HM Royal Dockyard, Sheerness as a new vessel. Sir William Symonds had redesigned the ship as a screw propeller driven vessel.

A Water wheel is a machine for converting falling or flowing water into useful power.

Steam-powered vessel Boat using steam pressure for propulsion

Steam-powered vessels include steamboats and steamships. Smaller steamboats were developed first. They were replaced by larger steamships which were often ocean-going. Steamships required a change in propulsion technology from sail to paddlewheel to screw to steam turbines. The latter innovation changed the design of vessels to one that could move faster through the water. Engine propulsion changed to steam turbine in the early 20th century. In the latter part of the 20th century, these, in turn, were replaced by gas turbines.

Cyclorotor Perpendicular axis marine propulsion system

A cyclorotor, cycloidal rotor, cycloidal propeller or cyclogiro, is a fluid propulsion device that converts shaft power into the acceleration of a fluid using a rotating axis perpendicular to the direction of fluid motion. It uses several blades with a spanwise axis parallel to the axis of rotation and perpendicular to the direction of fluid motion. These blades are cyclically pitched twice per revolution to produce force in any direction normal to the axis of rotation. Cyclorotors are used for propulsion, lift, and control on air and water vehicles. An aircraft using cyclorotors as the primary source of lift, propulsion, and control is known as a cyclogyro or cyclocopter. The patented application, used on ships with particular actuation mechanisms both mechanical or hydraulic, is named after the name of the German company Voith Turbo that produces them: Voith Schneider Propellers.

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