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Impeller
 
 
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An impeller is a rotor inside a tube or conduit to increase the pressure and flow of a fluid. mpeller is a rotating component of a centrifugal pump
Centrifugal pump

A centrifugal pump is a rotodynamic pump that uses a rotating impeller to increase the pressure of a fluid. Centrifugal pumps are commonly used to move liquids through a piping system....
, usually made of iron, steel, bronze, brass, aluminum or plastic, which transfers energy
Energy

In physics, energy is a scalar physical quantity that describes the amount of Work_ that can be performed by a force. Energy is an attribute of objects and systems that is subject to a conservation law....
 from the motor
Motor

Motor may refer to:*An engine:**Servo motor, it uses in robots it also haveing a inbuilt rotation sensor***Electric motor, a machine that converts electricity into a mechanical motion...
 that drives the pump to the fluid
Fluid

A fluid is defined as a substance that continually deforms under an applied shear stress. All liquids and all gases are fluids. Fluids are a subset of the Phase and include liquids, gas, Plasma physics and, to some extent, plasticity ....
 being pumped by accelerating the fluid outwards from the center of rotation.






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An impeller is a rotor inside a tube or conduit to increase the pressure and flow of a fluid.
Francis Runner Grandcoulee

Impellers in pumps

An impeller is a rotating component of a centrifugal pump
Centrifugal pump

A centrifugal pump is a rotodynamic pump that uses a rotating impeller to increase the pressure of a fluid. Centrifugal pumps are commonly used to move liquids through a piping system....
, usually made of iron, steel, bronze, brass, aluminum or plastic, which transfers energy
Energy

In physics, energy is a scalar physical quantity that describes the amount of Work_ that can be performed by a force. Energy is an attribute of objects and systems that is subject to a conservation law....
 from the motor
Motor

Motor may refer to:*An engine:**Servo motor, it uses in robots it also haveing a inbuilt rotation sensor***Electric motor, a machine that converts electricity into a mechanical motion...
 that drives the pump to the fluid
Fluid

A fluid is defined as a substance that continually deforms under an applied shear stress. All liquids and all gases are fluids. Fluids are a subset of the Phase and include liquids, gas, Plasma physics and, to some extent, plasticity ....
 being pumped by accelerating the fluid outwards from the center of rotation. The velocity achieved by the impeller transfers into pressure when the outward movement of the fluid is confined by the pump casing. Impellers are usually short cylinders with an open inlet (called an eye) to accept incoming fluid, vanes to push the fluid
Fluid

A fluid is defined as a substance that continually deforms under an applied shear stress. All liquids and all gases are fluids. Fluids are a subset of the Phase and include liquids, gas, Plasma physics and, to some extent, plasticity ....
 radially, and a splined, keyed or threaded bore to accept a driveshaft.

Impellers in water jets

Some impellers are similar to small propeller
Propeller

A propeller is a type of fan which transmits power by converting rotational motion into thrust. It can be used to drive an fixed-wing aircraft, ship, or the fluid within a pump....
s but without the large blades. Among other uses, they are used in water jets to power high speed boats.

Since impellers have no large blades to turn, they can spin at much higher speeds than propellers. The water forced through the impeller is channelled by the housing, creating a water jet that propels the vessel forward. The housing is normally tapered into a nozzle to increase the speed of the water, which also creates a Venturi effect
Venturi effect

The Venturi effect is the reduction in fluid pressure that results when a fluid flows through a constricted section of pipe. The fluid velocity must increase through the constriction to satisfy the Derivation of the Navier?Stokes equations#Conservation of mass, while its pressure must decrease due to conservation of energy: the gain in kin...
 in which low pressure behind the impeller pulls more water towards the blades, tending to increase the speed.

To work efficiently, there must be a close fit between the impeller and the housing. The housing is normally fitted with a replaceable wear ring which tends to wear as sand
Sand

Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.As the term is used by geologists, sand particles range in diameter from 0.0625 to 2 millimeters....
 or other particles are thrown against the housing side by the impeller.

Vessels using impellers are normally steered by changing the direction of the water jet.

Compare to propeller
Propeller

A propeller is a type of fan which transmits power by converting rotational motion into thrust. It can be used to drive an fixed-wing aircraft, ship, or the fluid within a pump....
 and jet
Jet engine

A jet engine is a reaction engine that discharges a fast moving jet of fluid to generate thrust in accordance with Isaac Newton Newton's laws of motion....
 aircraft
Aircraft

An aircraft is a vehicle which is able to flight by being supported by the air, or in general, the atmosphere, of a planet. Examples include balloons, airplanes and helicopters....
 engines.

Impellers in agitated tanks


Impellers in agitated tanks are used to mix fluids or slurry in the tank. This can be used to combine materials; solids, liquids, gas. Mixing the fluids in a tank is very important if there are gradient
Gradient

In vector calculus, the gradient of a scalar field is a vector field which points in the direction of the greatest rate of increase of the scalar field, and whose magnitude is the greatest rate of change....
s in conditions such as temperature or concentration.

There are two types of impellers, depending on the flow regime created (see figure):
  • axial flow impeller
  • radial flow impeller.


Radial flow impellers impose essentially shear stress
Shear stress

File:Shear stress.JPGA shear stress, denoted , is defined as a stress which is applied parallel or tangent to a face of a material, as opposed to a normal stress which is applied perpendicularly....
 to the fluid, and are used, for example, when we need to mix immiscible liquids or in general when there is a deformable interface
Interface (chemistry)

An interface is a surface forming a common boundary among two different phase , such as an insoluble solid and a liquid, two immiscible liquids or a liquid and an insoluble gas....
 to break. Another application of radial flow impellers are the mixing of very viscous fluids.
Axial flow impellers impose essentially bulk motion, and are used on homogenization processes, in which is important to increase fluid volumetric flow rate
Volumetric flow rate

The volumetric flow rate in fluid dynamics and hydrometry, is the volume of fluid which passes through a given surface per unit time Volumetric flow rate should not be confused with volumetric flux, as defined by Darcy's law and represented by the symbol q, with units of m3/, that is, m s-1....
.

Example

If one heats a pot of tomato soup on the stove the pot will develop a temperature gradient, (warmest on the bottom and cooler at the surface). Mild agitation will increase the rate of heating by dissipating the heat through the entire pot. See: Law of cooling
Heat conduction

Heat conduction or thermal conduction is the spontaneous heat transfer through matter, from a region of higher temperature to a region of lower temperature, and acts to equalize temperature differences....
 (which also applies to heating). Severe agitation may however decrease the rate of heating.

Impellers in washing machines


Some constructions of top loading washing machines use impellers to agitate
Agitator (device)

An agitator is a mechanism to put something into Motion by shaking or stirring....
 the laundry during washing.

Firefighting rank badge

Fire services in the United Kingdom
United Kingdom

The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom , the UK or Britain,is a sovereign state located off the northwestern coast of continental Europe....
 and many countries of the Commonwealth
Commonwealth of Nations

The Commonwealth of Nations, also known as the Commonwealth or the British Commonwealth, is an intergovernmental organization of fifty-three independent member states....
 use a stylized depiction of an impeller as a rank badge. Officers wear one or more on their epaulette
Epaulette

Epaulette is a French language word meaning "little shoulder" . Epaulettes are a type of ornamental shoulder piece or decoration used as insignia or military rank by the armed force and other organizations....
s or the collar of their firefighting uniform as an equivalent to the "pips" worn by the army
Army

An army , in the broadest sense, is the land-based armed forces of a nation. It may also include other branches of the military such as an air force....
 and police
Police

Police are agents or agencies, usually of the executive , empowered to enforce the law and to ensure public and social order through the legitimized use of force....
.

Impellers in gas turbine engines (Turboprop
Turboprop

A turboprop engine is a type of aircraft engine that uses a gas turbine to drive a propeller. The gas turbine is designed specifically for this application, with almost all of its output being used to drive the propeller....
)

Some turboprop engines use an impeller instead of an axial compressor. For example the Pratt & Whitney Canada PW100
Pratt & Whitney Canada PW100

Pratt & Whitney Canada's PW100 engine family is a series of 2,000 to 5,000 horsepower turboprops manufactured by Pratt and Whitney's Canadian subsidiary....
 uses a two stage compressor with a low power impeller discharging air pressure on the high power impeller which compresses the air again into the combustion chamber. The fuel is is mixed in at over 200 PSI and the mixture burns in the combustion chamber. The reason for using an impeller instead of an axial compressor is that the engines length can be reduced.