>SurajSinghChennai at 10:18, 27 December 2021

2021-12-27T10:18:07Z

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[[File:Water nozzle.jpg|thumb|A water nozzle]]
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| header= [[Center pivot irrigation]] [[Irrigation sprinkler|sprinkler]] nozzles, used in [[crop]] [[irrigation]]
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| image1 = Nelson A3000 Accelerator.png
| width1 = 116
| caption1 = Rotator style pivot applicator sprinkler
| image2 = Nelson Big Gun.png
| width2 = 116
| caption2 = End Gun style pivot applicator sprinkler
}}
A '''nozzle''' is a device designed to control the direction or characteristics of a [[fluid]] flow (especially to increase velocity) as it exits (or enters) an enclosed chamber or [[pipe (material)|pipe]].

A nozzle is often a pipe or tube of varying cross sectional area, and it can be used to direct or modify the flow of a fluid ([[liquid]] or [[gas]]). Nozzles are frequently used to control the rate of flow, speed, direction, mass, shape, and/or the pressure of the stream that emerges from them. In a nozzle, the velocity of fluid increases at the expense of its pressure energy.

==Types==

===Jet===
A '''gas jet''', '''fluid jet''', or '''hydro jet''' is a nozzle intended to eject gas or fluid in a coherent stream into a surrounding medium. Gas jets are commonly found in [[gas stove]]s, [[oven]]s, or [[barbecue]]s. Gas jets were commonly used for [[Gas lighting|light]] before the development of [[electric light]]. Other types of fluid jets are found in [[carburetor]]s, where smooth [[calibrated orifice]]s are used to regulate the flow of [[gasoline|fuel]] into an engine, and in [[jacuzzi]]s or [[spa]]s.

Another specialized jet is the [[Laminar flow|laminar]] jet. This is a water jet that contains devices to smooth out the pressure and flow, and gives [[laminar flow]], as its name suggests. This gives better results for [[fountain]]s.

The foam jet is another type of jet which uses foam instead of a gas or fluid.

Nozzles used for feeding [[hot blast]] into a [[blast furnace]] or [[forge]] are called [[tuyere]]s.

Jet nozzles are also used in large rooms where the distribution of air via ceiling diffusers is not possible or not practical. Diffusers that uses jet nozzles are called jet diffuser where it will be arranged in the side wall areas in order to distribute air. When the temperature difference between the supply air and the room air changes, the supply air stream is deflected upwards, to supply warm air, or downwards, to supply cold air.<ref>"Jet nozzles, Type DUK" from TROX company, retrieved 15 October 2013 from http://www.troxaustralia.com/xpool/download/en/technical_documents/diffusers/leaflets/t_1_2_2_duk.pdf {{Webarchive|url=https://web.archive.org/web/20131015190001/http://www.troxaustralia.com/xpool/download/en/technical_documents/diffusers/leaflets/t_1_2_2_duk.pdf |date=15 October 2013 }}</ref>

===High velocity===
[[File:Raketendüse.jpg|thumb|A nozzle from the Ariane-5 rocket]]

Frequently, the goal of a nozzle is to increase the [[kinetic energy]] of the flowing medium at the expense of its [[pressure]] and [[internal energy]].

Nozzles can be described as ''convergent'' (narrowing down from a wide diameter to a smaller diameter in the direction of the flow) or ''divergent'' (expanding from a smaller diameter to a larger one). A [[de Laval nozzle]] has a convergent section followed by a divergent section and is often called a convergent-divergent (CD) Nozzle ("con-di nozzle").

Convergent nozzles accelerate subsonic fluids. If the nozzle pressure ratio is high enough, then the flow will reach sonic velocity at the narrowest point (i.e. the ''nozzle throat''). In this situation, the nozzle is said to be ''choked''.

Increasing the nozzle pressure ratio further will not increase the throat [[Mach number]] above one. Downstream (i.e. external to the nozzle) the flow is free to expand to supersonic velocities; however, Mach 1 can be a very high speed for a hot gas because the [[speed of sound]] varies as the square root of absolute temperature. This fact is used extensively in rocketry where [[hypersonic]] flows are required and where propellant mixtures are deliberately chosen to further increase the sonic speed.

Divergent nozzles slow fluids if the flow is subsonic, but they accelerate sonic or supersonic fluids.

Convergent-divergent nozzles can therefore accelerate fluids that have choked in the convergent section to supersonic speeds. This CD process is more efficient than allowing a convergent nozzle to expand supersonically externally.
The shape of the divergent section also ensures that the direction of the escaping gases is directly backwards, as any
sideways component would not contribute to thrust.

===Propelling===
{{main|Propelling nozzle}}
A jet exhaust produces a net thrust from the energy obtained from combusting fuel which is added to the inducted air. This hot air passes through a high speed nozzle, a ''propelling nozzle'', which enormously increases its kinetic energy.<ref>GFC Rogers, and Cohen, H. ''Gas Turbine Theory'', p.108 (5th Edition), HIH Saravanamuttoo</ref>

Increasing exhaust velocity increases thrust for a given mass flow, but matching the exhaust velocity to the air speed provides the best energy efficiency. However, momentum considerations prevent jet aircraft from maintaining velocity while exceeding their exhaust jet speed. The engines of supersonic jet aircraft, such as those of [[fighter aircraft|fighters]] and [[Supersonic transport|SST]] aircraft (e.g. [[Concorde]]) almost always achieve the high exhaust speeds necessary for supersonic flight by using a CD nozzle despite weight and cost penalties; conversely, subsonic jet engines employ relatively low, subsonic, exhaust velocities and therefore employ simple convergent nozzle, or even [[bypass ratio|bypass]] nozzles at even lower speeds.

[[Rocket motor]]s maximise thrust and exhaust velocity by using convergent-divergent nozzles with very large area ratios and therefore extremely high pressure ratios. Mass flow is at a premium because all the propulsive mass is carried with vehicle, and very high exhaust speeds are desirable.

===Magnetic===
[[Magnetic nozzle]]s have also been proposed for some types of propulsion, such as [[Variable Specific Impulse Magnetoplasma Rocket|VASIMR]], in which the flow of [[Plasma (physics)|plasma]] is directed by [[magnetic field]]s instead of walls made of solid matter.

===Spray===
{{main|Spray nozzle}}
Many nozzles produce a very fine spray of liquids.
* '''[[Atomizer nozzle]]s''' are used for spray painting, perfumes, [[carburetor]]s for [[internal combustion engine]]s, spray on [[deodorant]]s, [[antiperspirant]]s and many other similar uses.
* '''Air-Aspirating Nozzle '''uses an opening in the cone shaped nozzle to inject air into a stream of water based foam (CAFS/AFFF/FFFP) to make the concentrate "foam up". Most commonly found on foam extinguishers and foam handlines.
* '''Swirl nozzles''' inject the liquid in tangentially, and it spirals into the center and then exits through the central hole. Due to the vortexing this causes the spray to come out in a cone shape.

===Vacuum===
[[Vacuum cleaner]] nozzles come in several different shapes. Vacuum Nozzles are used in vacuum cleaners.

===Shaping===
Some nozzles are shaped to produce a stream that is of a particular shape. For example, [[extrusion molding]] is a way of producing lengths of metals or plastics or other materials with a particular cross-section. This nozzle is typically referred to as a [[Die (manufacturing)|die]].

==See also==
* [[Fire_hose#Forces_on_fire_hoses_and_nozzles|Nozzle reaction]]
* [[Rocket engine nozzle]]
* [[SERN]]
* [[Spray nozzle]]

==References==
{{Reflist}}

==External links==
{{Wiktionary}}
* {{cite web|url=http://exploration.grc.nasa.gov/education/rocket/nozzle.html|title=Nozzle design (converging/diverging - CD nozzle)|access-date=19 January 2009|publisher=[[NASA]].gov|archive-date=20 March 2009}}

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[[Category:Nozzles]]
[[Category:Fluid mechanics]]

Nozzle - Revision history

>SurajSinghChennai at 10:18, 27 December 2021