venturi tube


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Related to venturi tube: Bernoulli's principle, Pitot tube

Venturi tube

A device that consists of a gradually decreasing nozzle through which the fluid in a pipe is accelerated, followed by a gradually increasing diffuser section that allows the fluid to nearly regain its original pressure head (see illustration). It can be used to measure the flow rate in the pipe, or it can be used to pump a secondary fluid by aspirating it at the nozzle exit. The ability of the venturi tube to regain much of the original pressure head makes it especially useful in measuring the flow rate in systems which have a low pressure differential or pressure head that drives the fluid through the pipe or where the cost of pumping the fluid is an important factor. Conserving the pressure head decreases the amount of energy required to pump the fluid through the pipe.

Proportions of a Herschel-type venturi tube for standard fluid-flow measurementenlarge picture
Proportions of a Herschel-type venturi tube for standard fluid-flow measurement

A gradual expansion of flow downstream of a nozzle eliminates flow separation, allowing recovery of most of the original pressure head. In the case where the main flow separates from the wall, a large percentage of the fluid energy is lost in the eddies caused by the separation.

The flow through the device obeys Bernoulli's equation, and the formula for calculating the flow is similar to the equation for orifices. The venturi meter belongs to the class of differential pressure-sensing devices that are used to indicate flow. See Bernoulli's theorem

venturi tube

[ven′tu̇r·ē ‚tüb]
(engineering)
A constriction that is placed in a pipe and causes a drop in pressure as fluid flows through it, consisting essentially of a short straight pipe section or throat between two tapered sections; it can be used to measure fluid flow rate (a venturi meter), or to draw fuel into the main flow stream, as in a carburetor.

Venturi tube

A device that consists of a gradually decreasing nozzle through which the fluid in a pipe is accelerated, followed by a gradually increasing diffuser section that allows the fluid to nearly regain its original pressure head (see illustration). It can be used to measure the flow rate in the pipe, or it can be used to pump a secondary fluid by aspirating it at the nozzle exit. The ability of the venturi tube to regain much of the original pressure head makes it especially useful in measuring the flow rate in systems which have a low pressure differential or pressure head that drives the fluid through the pipe or where the cost of pumping the fluid is an important factor. Conserving the pressure head decreases the amount of energy required to pump the fluid through the pipe.

A gradual expansion of flow downstream of a nozzle eliminates flow separation, allowing recovery of most of the original pressure head. In the case where the main flow separates from the wall, a large percentage of the fluid energy is lost in the eddies caused by the separation.

The flow through the device obeys Bernoulli's equation, and the formula for calculating the flow is similar to the equation for orifices. The venturi meter belongs to the class of differential pressure-sensing devices that are used to indicate flow. See Flow measurement, Metering orifice

venturi tube

venturi tube
Flow pattern through a venturi tube.
A tube that gradually narrows to a throat and then expands even more gradually to the exit. It is used to prove Bernoulli's theorem. In a venturi tube, the mass flow is constant and at any point the product of the pressure (P), a crosssectional area (a), and the speed (V) is constant. This is known as the venturi effect.
References in periodicals archive ?
The numerical simulation can be used in the design for optimum solution whenever available upstream straight length is insufficient for high accuracy installation as results from this work indicate the discharge coefficients between Venturi tube with 10D upstream straight length and Venturi tube with 3D upstream straight length are within +/-0.5% error (uncertainty).
ABSTRACT: The installation of Venturi tubes for high accuracy flow measurement in industrial application is normally based on the available international standards and guidelines.
In this work, the numerical simulation was used to investigate the impact on the discharge coefficient, Cd, for installation with upstream straight length lesser than the given minimum value by comparing the numerical simulation results and experimental data, for Venturi tubes ranging from 100 mm to 250 mm.
on the influence of upstream bends on the discharge coefficients, Cd, of classical Venturi tubes and orifice plates indicated that the for pipe bends upstream of an orifice with undisturbed inlet sections smaller, as demanded in ISO 5167-1, it was recommended to install the pressure taps in the direction of the inner side of the bend (0o angle position) [1].
In 2003, International Standardization Organization (ISO) committee produced the revision 2003 of the ISO 5167 international standard which covers the guidelines on upstream straight requirement for differential pressure devices, such as Venturi tubes and orifice plates.
This paper presents the work on using Computational Fluid Dynamics (CFD) to investigate the impact of upstream straight length on the measurement accuracy of Venturi tubes, in accordance to ISO 5167-4 [3].
The work involved setting up the models in the ANSYS DesignModeller, similar to the physical Venturi tubes used in the experimental calibration.
The National Engineering Laboratory (NEL) in the United Kingdom was used to perform the experimental calibration of the Venturi tubes. The experimental setup was based on 20D upstream straight length pipe spool, which is way beyond the minimum "zero additional uncertainty" upstream straight length as indicated by ISO 5167-4.
Table 1, 2, 3 and 4 provide the overview of the test matrix for each size of the Venturi tubes.
10, 11, 12, 13, 14, 15, 16 and 17 are the pressure distribution contours for all the configurations of the upstream straight length and Venturi tubes' sizes.
7 Pull out the burner, sliding the venturi tubes free from their mounting slots.
8 Push a venturi cleaning brush ($6) or large pipe cleaner into the end of the venturi tubes to clean out spider webs (a common obstruction) and other debris.