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Archimedes' screw

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An Archimedes' screw is a hydraulic machine used to move liquids from one place to another. It consists of an outer cylinder and an inner cylinder containing helical blades. These blades are shaped like a continuous spiral around a central shaft. This machine is highly versatile because it can function as a pump or a power generator. It is also used for drainage and sewage management.

Archimedes Schraube
Archimedes Schraube

By moving water efficiently, it helps manage land and water systems across the world.

The mechanism of the screw relies on rotation to transport liquid. To use it as a pump, the screw is turned by manual labor, animals, or a motor. As the central shaft turns, the bottom end of the screw scoops up a volume of water. The rotating helical blades then push this water up through the tube. The water continues to rise until it pours out from the top of the cylinder.

Water screw by Vitruvius
Water screw by Vitruvius

Interestingly, the machine can also work in reverse to create energy. If water is poured into the top, the weight of the falling water forces the screw to rotate. This spinning motion can drive an electric generator to produce power.

There are several distinct types of Archimedes' screw designs. Spiral screws consist of small closed tubes wrapped around a larger tube. Trough screws use helical blades wrapped around a central tube within a U-shaped trough. Tube screws feature helical blades inside a central tube that is enclosed in a cylinder. Finally, casing tube screws have blades attached to an enclosed cylinder, causing the entire structure to rotate.

Mähdrescher Schnecke
Mähdrescher Schnecke

Manufacturers often avoid spiral, tube, or casing designs because they can trap air or have poor ventilation.

The exact origins of the water screw remain a subject of historical debate. Archimedes of Syracuse is traditionally credited with its invention. Some historians believe he invented it after seeing a water wheel in Egypt between 283 and 246 BC. However, other scholars argue that Egyptians were already using the device. Assyriologist Stephanie Dalley suggests bronze screws were used to irrigate the Hanging Gardens of Babylon.

Water screw by Vitruvius
Water screw by Vitruvius

Archaeological remains show the screw spread through the Roman Empire in places like Spain and Italy. It fell out of use in Europe by the third century AD, but it later resurfaced during the Renaissance.

During the Renaissance, the screw saw a major revival in scientific study. Engineers like Leonardo da Vinci and Agostino Ramelli documented the machine in their works. In the Netherlands, windmill-powered screws were essential during the Dutch Golden Age for land drainage. These machines could move large amounts of water even in low heads. In 1991, Karl-August Radlik filed a patent for the Archimedes screw turbine (AST). Testing between 1993 and 1995 proved that these turbines can convert most hydraulic energy into mechanical energy.

Modern Archimedes' screw turbines are significant for small hydroelectric powerplants. They are particularly useful in low-head sites, which are areas with very little vertical drop. These generators can operate across a wide range of flows, from 0.01 m3/s to 14.5 m3/s. They also work with heads ranging from 0.1 m to 10 m.

IMG 1729 Gemaal met schroef van Archimedes bij Kinderdijk
IMG 1729 Gemaal met schroef van Archimedes bij Kinderdijk

This makes them ideal for locations where traditional high-performance turbines are not practical. They provide a reliable way to capture energy from moderate flow rates.

The screw is also highly valued for its environmental benefits. Because the turbines rotate at a low speed, they are considered fish-friendly. This reduces the negative effects on aquatic life compared to other power systems. Additionally, the design can handle very dirty water and widely varying flow rates with high efficiency.

IMG 1729 Gemaal met schroef van Archimedes bij Kinderdijk
IMG 1729 Gemaal met schroef van Archimedes bij Kinderdijk

These qualities make the Archimedes' screw a vital tool in modern wastewater treatment and sustainable energy production.

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File:Water screw by Vitruvius.png
Water screw by Vitruvius.png
File:Archimedes Schraube.jpg
Archimedes Schraube.jpg
File:IMG 1729 Gemaal met schroef van Archimedes bij Kinderdijk.JPG
IMG 1729 Gemaal met schroef van...
File:Mähdrescher Schnecke.jpg
Mähdrescher Schnecke.jpg
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