Venturi effect

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The Venturi effect is a reduction in fluid pressure that occurs when the liquid flows through the limited (or choked) portion of a pipe. The Venturi effect was named after Giovanni Battista Venturi (1746-1822), an Italian physicist.

Video Venturi effect

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In the fluid dynamics, the speed of the compressed fluid must increase as it passes the narrowing according to the principle of mass continuity, while the static pressure must decrease according to the principle of mechanical energy conservation. Thus, any increase in kinetic energy of a fluid may increase due to its increased velocity through a constriction balanced by the pressure drop.

By measuring pressure changes, flow rates can be determined, as in various flow measuring devices such as venturi meters, venturi nozzles and orifice plates.

Mengacu through the yang berdekatan diagram, menggunakan persamaan Bernoulli dalam kasus khusus aliran stabil, mampat, tidak tembus cahaya (seperti aliran air atau cairan lainnya, atau aliran kecepatan rendah gas) sepanjang arus, penurunan tekanan theoritis pada penyempitan adalah diberikan oleh:

${\ displaystyle p_ {1} -p_ {2} = {\ frac {\ rho} {2}} \ kiri (v_ {2} ^ 2 } -v_ {1} 2} \ kanan)} Â Â$

di mana ${\ displaystyle \ scriptstyle \ rho \,}  ÂÂ$ adalah densitas dari fluida, ${\ displaystyle \ scriptstyle v_ {1}}  ÂÂ$ adalah kecepatan fluida (lebih lambat) di mana pipa lebih lebar, ${\ displaystyle \ scriptstyle v_ {2}}  ÂÂ$ adalah kecepatan fluida (lebih cepat) di mana pipa lebih sempit (seperti yang terlihat pada gambar).

Aliran tersendat

The case that limits the Venturi effect is when a fluid reaches a stagnant flow state, where the fluid velocity is close to the local sound velocity. When the fluid system is in a stagnant flow state, a further decrease in the downstream pressure environment will not cause an increase in mass flow rate. However, the mass flow rate for the compressible fluid will increase with increasing upstream pressure, which will increase the fluid density through constriction (although the velocity will remain constant). This is the operating principle of the nozzle de Laval. Increased source temperatures will also increase local sonic speed, thus allowing an increase in mass flow rate but only if the nozzle area is also increased to compensate for the resulting density reduction.

Maps Venturi effect

Experimental tools

Venturi Tube

The simplest tool, as shown in photos and diagrams, is a tubular installation known as a Venturi tube or just a venturi. Fluid flows through the length of the pipe with varying diameters. To avoid undue aerodynamic drag, the Venturi tube usually has a cone of 30 degrees and a cone 5 degrees out.

The venturi tube is used in a process where permanent pressure loss is intolerable and where maximum accuracy is required in the case of very viscous liquids.

Orifice plate

The venturi tube is more expensive to build than simple orifice plates that use the same principle as the tubular scheme, but the orifice plate causes significant permanent loss of energy.

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Instrumentation and measurement

Venturis is used in industrial applications and in scientific laboratories to measure the rate of liquid flow.

Flow rate

Venturi dapat digunakan untuk mengukur laju aliran volumetrik, ${\ displaystyle \ scriptstyle Q}  ÂÂ$ .

Sejak

Venturi can also be used to mix liquids with gas. If the pump forces the liquid through a tube connected to a system consisting of a venturi to increase the fluid velocity (decreased diameter), a short tube piece with a small hole in it, and the last venturi that reduces the speed (so the pipe gets wider), the gas will be sucked in through small hole due to pressure changes. At the end of the system, a mixture of liquids and gases will appear. See aspirator and head pressure for a discussion of this siphon type.

Differential pressure

When the liquid flows through the venturi, fluid expansion and compression causes the pressure inside the venturi to change. This principle can be used in metrology for calibrated gauges for differential pressure. This type of pressure measurement may be more convenient, for example, to measure fuel pressure or combustion in a jet engine or a rocket. The first large-scale Venturi meter for measuring liquid flow was developed by Clement Herschel who used it to measure the flow of small and large water that began in the late 19th century.

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Example

Venturi effects can be observed or used as follows:

• Cargo eductors on oil products and chemical tankers
• Inspirators that mix air and combustible gas in grills, gas stove, Bunsen burner and airbrush
• Water aspirator that produces a partial vacuum using kinetic energy from water faucet pressure
• Steam chiffons use the kinetic energy of the vapor pressure to create a partial vacuum
• Atomizers who spread perfume or spray paint (ie from a spray gun).
• A carburetor that uses effects to suck gasoline into the inlet airflow
• Aerators of wine, used to put air into wine when poured into a glass
• Capillary circulatory system in humans, where it shows aortic regurgitation
• Aortic insufficiency is a chronic heart condition that occurs when the large stroke volume of the initial aortic valve is released and the Venturi effect pulls the walls together, blocking blood flow, leading to pulsus bisferiens.
• Skimmer protein (filtration tool for saltwater aquarium)
• In automatic pool cleaners that use side pressure water flow to collect sediment and debris
• Modern clarinet claws, which use reverse taper to accelerate the air down the tube, allowing better tone, response, and intonation
• Industrial air-operated vacuum cleaner
• Venturi scrubber is used to clean the exhaust emissions
• Injectors (also called ejectors) are used to add chlorine gas to a water treatment chlorination system
• The steam injector uses the Venturi effect and the latent heat of evaporation to send the feed water to the steam locomotive boiler.
• Sandblasting nozzles use the Venturi effect to speed up air and media mix.
• Stomach water that empties from a boat that travels through a small waste gate in the stomach - the air pressure inside the boat that moves larger than the water slips below
• Scuba diving manager to help airflow after start flow
• In a recoilless rifle to reduce the retreat of the shot
• Ventilator
• Diffuser on car
• Racing cars utilized ground effects to increase downforce and thus became capable of higher cornering speeds, from the late 1970s until the technology was banned from competition in the early to mid 1980s
• Big cities where wind is forced between buildings - the gap between the original Twin Towers of the World Trade Center is an extreme example of pheonomenon, which makes the plaza on the land surface famous for its windswept. In fact, some gusts are so high that a pedestrian journey should be aided by a rope.
• In passing a windy mountain, it produces a false altimeter reading reading
• The main stem of the trombone, affecting timbre
• Foam propaganda is used to insert the fire foam concentrate into the fire protection system
• Trompe air compressor to trap air into the falling water column
• The Mistral Wind in Southern France increases speed through the Rhone valley.

The venturi tube is also used to measure the velocity of the liquid, by measuring pressure changes on various segments of the device. Placing liquid in a U-shaped tube and connecting the tip of the tube to both ends of Venturi is all that is needed. When the liquid flows through Venturi, the pressure at both ends of the tube will be different, forcing the liquid to the "low pressure" side. The amount of movement can be calibrated to the fluid flow velocity.

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See also

• Joule-Thomson effect
• Venturi flume
• Bernoulli Principle
• De Laval nozzle
• Bunsen burner
• Stuttering flow
• Orifice Plates
• The pitot tube

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References

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External links

• 3D animation of the Differential Pressure Flow Measurement Principle (Venturi meter)
• UT Austin. "Simulation of Venturi Tubes" . Retrieved 2009-11-03 .

Source of the article : Wikipedia