# Velocity of fluid in venturi tube

• Dennydont
In summary, a venturi tube is used to measure fluid velocity and consists of a circular pipe with varying radii. In this particular case, the pressure difference between the wide and narrow parts is 3.5 kN/m^2 and the density of the liquid is 1120 kg/m3. Using the continuity and Bernoulli equations, the velocity of the fluid in the wide part of the pipe was found to be 2.5 m/s, but this was incorrect.
Dennydont

## Homework Statement

A venturi tube is a means of measuring fluid velocity. One particular device consists of a level, circular pipe of radius 5.7 cm which at one point narrows to a radius of 3.7 cm. An ideal, incompressible liquid flows through the tube and the pressure difference between the wide and narrow parts is found to be 3.5 kN/m^2. If the density of the liquid is 1120 kg/m3 what is the velocity of the fluid in the wide part of the pipe?
ρ = 1120 kg/m^3
∆P = 3.5kN/m^2

## Homework Equations

Continuity: ρA1v1 = ρA2v2
Bernoulli: P + 1/2ρv^2 + ρgh

## The Attempt at a Solution

I tried finding v1 by using the rearranging Bernoulli's equation v = √((2∆P)/ρ) = 2.5m/s
Then using continuity equation, tried to find v2 which happened to equal 1.05m/s. Incorrect.

Last edited:
Dennydont said:

## Homework Statement

A venturi tube is a means of measuring fluid velocity. One particular device consists of a level, circular pipe of radius 5.7 cm which at one point narrows to a radius of 3.7 cm. An ideal, incompressible liquid flows through the tube and the pressure difference between the wide and narrow parts is found to be 3.5 kN/m^2. If the density of the liquid is 1120 kg/m3 what is the velocity of the fluid in the wide part of the pipe?
ρ = 1120 kg/m^3
∆P = 3.5kN/m^2

## Homework Equations

Continuity: ρA1v1 = ρA2v2
Bernoulli: P + 1/2ρv^2 + ρgh
You need the Bernoulli equation. What you wrote it was not an equation.

## 1. What is a venturi tube?

A venturi tube is a device used to measure the velocity of fluid flow in a pipe. It consists of a tapered tube with a narrower throat in the middle and pressure taps on either side of the throat.

## 2. How does a venturi tube measure fluid velocity?

A venturi tube works on the principle of Bernoulli's equation, which states that as the velocity of a fluid increases, the pressure decreases. The pressure difference between the two taps on either side of the venturi throat can be used to calculate the fluid velocity.

## 3. What are the advantages of using a venturi tube?

One advantage of using a venturi tube is that it has a low pressure loss, meaning that it does not significantly impede the flow of the fluid. It is also relatively simple and inexpensive to construct, and can be used for a wide range of fluid velocities.

## 4. What are the limitations of using a venturi tube?

A venturi tube is limited in its use for fluids that are clean and free from particles or bubbles. It is also not suitable for measuring the velocity of low viscosity fluids, such as gases, as they may not produce a significant pressure difference.

## 5. How accurate is a venturi tube in measuring fluid velocity?

The accuracy of a venturi tube depends on various factors, such as the design and construction of the tube, the properties of the fluid being measured, and the skill of the operator. Generally, a well-designed venturi tube can provide accurate velocity measurements within a range of 2-3%.

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