Propeller

Geometry

In Geometry, the propeller is a Courbe whose tangent in each point makes a constant Angle with a given direction.

To obtain a simple propeller of manner, to take a rectangular sheet , to trace a Diagonal and to roll up the sheet to form a cylinder; the feature forms a propeller. It is also the form of the Ressort S with roll, of the Solénoïde S and the Filetage S and Taraudage S.

One can describe a propeller of axis Z , ray R and step p by the parametric equation following:

\ left \ {\ begin {matrix}

X (T) = x_0 + R \ cdot \ cos (2 \ pi \ cdot T) \ \ there (T) = y_0 + R \ cdot \ sin (2 \ pi \ cdot T) \ \ Z (T) = z_0 + p \ cdot T \end{matrix} \right .

Seen in the axis, the propeller is projected according to a Cercle. Of profile, it is projected according to a Sinusoïde.

Mechanics

For the Mechanical , the propeller is an apparatus of traction, Compression, Propulsion, Sustentation, or conversely or of measurement, made of several Pale S laid out regularly around a axis. When its axis enters in rotation, this system describes propellers in a fluid while advancing perpendicular to rotation, thanks to the blades directed according to a certain angle or Pas which takes support on the fluid. A propeller can thus be driving (transfer of energy towards the fluid: plane) or receiving (recuperation of energy since the fluid: harness, wind or aerogenerator); profile of the blades being optimized for the envisaged use.

Applications

Driven by an engine, the propeller is used for the displacement of a Machine in a fluid and, conversely to drive a fluid in a container (the motionless machine remaining). There is transfer of energy of the engine towards the fluid.
Associated with a Sensor, it serves to measure the rate of travel as a fluid, or the displacement of an object in a fluid. There is theoretically no transfer of energy.
Associated with a receiver or a generator, it is used to recover energy in a fluid moving relative (" alternators traîne" and released behind certain sailing ships, windmills, aerogenerator, certain turbines of powerplants,…). There is transfer of energy of the fluid towards the engine.

Marine propeller

Known in its principles by the phenicians and the Greeks of the antiquity, described by Archimedes, used for the irrigation, then quickly forgotten until its application to the propulsion of the ships, allotted to the French engineer Wild Frederic in 1832 on a Barge of the Ourcq of 15 feet, then by the Canadian engineer John Patch on a Schooner in Bay of Fundy in 1834, both scorned by their governments respective and died in misery, whereas their discovery triumphed thanks to the interest carried in 1840 by the British navy with the demonstration over the engineer Smith on the Steamer Archimedes . The propeller became since the means of Propulsion more running to move a Bateau or a Sous-marin.

Cavitation can appear if the propeller is subjected to a force more important than that being able to be transmitted to water. That led to a loss of energy, an increase in the noise produced by the propeller and especially to an erosion of the surface of the propeller. However, cavitation can be a sought effect, as in the devices of propulsion to Supercavitation.

Joseph Ressel, arising from the Austro-Hungarian empire, is the inventor of the propulsion of a ship by a propeller (invention patented in 1827).

See too

Internal bonds

Hélicoïde
Hélice of Lynen
Hélices in biochemistry
Propeller
Hélice marinades

Simple: Propeller

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