Name: venturi meter flow rate from pressure
Uploaded: 2026-01-30T03:08:31.000Z
Duration: 1 min 16 s
Channel: JoVE

Un compteur Venturi est installé dans un système d’égouts pour mesurer le débit des eaux usées. Si le débit est connu et que les effets visqueux sont négligeables, quelle est la différence de pression indiquée par le manomètre fixé au débitmètre ?
Tout d’abord, calculez les sections transversales du tuyau et de la gorge à l’aide de leurs diamètres respectifs.
Ensuite, à l’aide de l’équation de continuité, déterminez les vitesses aux deux sections en fonction du débit donné.
Étant donné que l’aire et la vitesse sont inversement liées, les eaux usées s’accélèrent lorsqu’elles se déplacent du tuyau de plus grand diamètre vers la plus petite gorge.
Ensuite, appliquez l'équation de Bernoulli, qui relie la différence de pression entre deux points de l'écoulement à la variation de vitesse.
Cette équation montre que lorsque la vitesse augmente lorsque l’eau se déplace du plus grand tuyau vers la plus petite gorge, il y aura une chute de pression correspondante.
Enfin, calculez la différence de pression entre le tuyau et la gorge en substituant les vitesses dans l'équation de Bernoulli.
Le manomètre fixé au débitmètre indiquera la différence de pression finale.

résolution de problèmes par équation de bernoulli

Un débitmètre Venturi est essentiel pour mesurer les débits de fluides dans les canalisations. Il utilise la relation entre la vitesse du fluide et la pression décrite par l'équation de Bernoulli. Lorsqu'il est installé dans un système d'égouts, le débitmètre Venturi détermine avec précision le débit des eaux usées en mesurant les différences de pression.

La première étape consiste à calculer les sections transversales du tuyau et du col Venturi pour analyser la différence de pression indiquée par le manomètre. Ensuite, l'équation de continuité est appliquée, qui stipule que le débit volumétrique (Q) reste constant le long de la canalisation pour un fluide incompressible:

<img alt="Equation 1" src="/files/ftp_upload/18035/18035_Equation_1.svg" style="text-align: center; height: 12px;">

A_1 et A_2 sont les sections transversales du tuyau et du col, et V_1 et V_2 sont les vitesses du fluide dans ces sections. En réorganisant l'équation, la vitesse au niveau du col peut être exprimée comme suit:

<img alt="Equation 2" src="/files/ftp_upload/18035/18035_Equation_2.svg" style="text-align: center; height: 30px;">

Ainsi, les vitesses V_1 et V_2 peuvent être calculées pour un débit donné.

L'équation de Bernoulli relie la pression et la vitesse dans un fluide idéal, donnée par:

<img alt="Equation 3" src="/files/ftp_upload/18035/18035_Equation_3.svg" style="text-align: center; height: 27px;">

Ici, P_1 et P_2 sont les pressions dans le tuyau et le col et ⍴ est la densité du fluide. La différence de pression (P_1 - P_2) peut être calculée en remplaçant les vitesses V_1 et V_2 dans cette équation. Cette chute de pression (ΔP), indiquée par le manomètre, reflète l'augmentation de la vitesse lorsque les eaux usées s'écoulent dans le col plus étroit, ce qui est cohérent avec la conservation de l'énergie.

Résolution de problèmes par équation de Bernoulli

Un compteur Venturi est installé dans un système d’égouts pour mesurer le débit des eaux usées. Si le débit est connu et que les effets visqueux sont négligeables, qu’est-ce que...

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Bernoulli's Equation: Problem Solving

venturi meter flow rate from pressure

A Venturi meter measures fluid flow rate in a pipeline by using pressure changes and Bernoulli's equation. In a sewage system, it can be used to determine wastewater flow rate by reading the pressure difference across the meter. The narrowed throat makes the fluid speed up, and that change in speed is linked to pressure drop.

The first step is to find the cross-sectional areas of the pipe and the Venturi throat. These areas are needed to interpret the pressure difference shown on the pressure gauge. Next, the continuity equation is applied. For an incompressible fluid, the volumetric flow rate Q stays constant, and the pipe and throat areas are written as A1 and A2 with velocities V1 and V2.

From the continuity equation, the throat velocity can be rearranged and calculated from the flow rate. Once V1 and V2 are known, Bernoulli's equation is used to relate pressure and velocity in an ideal fluid. With the fluid density included, the pressures P1 and P2 in the pipe and throat can be compared to find the pressure difference.

Substituting the velocities into Bernoulli's equation gives the pressure drop, ΔP. That pressure drop is the value indicated by the pressure gauge. It reflects the increase in fluid speed as wastewater moves through the narrower throat, which follows energy conservation.

Venturi Meter Flow Rate from Pressure

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bernoulli's equation: problem solving

A Venturi meter measures fluid flow rate in a pipeline by using pressure changes and Bernoulli's equation. In a sewage system, it can be used to determine wastewater flow rate by reading the pressure difference across the meter. The narrowed throat makes the fluid speed up, and that change in speed is linked to pressure drop. The first step is to find the cross-sectional areas of the pipe and the Venturi throat. These areas are needed to interpret the pressure difference shown on the pressure...

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key terms and concepts

See how a Venturi meter uses continuity and Bernoulli's equation to turn pressure differences into wastewater flow rate in a sewage system.

Venturi Meter Flow Rate from Pressure | JoVE K12

JoVE Core Civil Engineering provides a foundational exploration of essential construction materials in civil engineering, focusing on bricks, stones, steel, wood, and concrete through easy-to-understand animated videos. This collection covers the properties, manufacturing processes, and practical applications of these materials. Additionally, the accompanied science-in-action videos demonstrate the research experiments performed in laboratories.

civil engineering

Venturi Meter Flow Rate from Pressure

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