Table of Contents
Introduction of Venturimeter
A venturimeter is a device used to measure the flow or leakage of a liquid through a pipe. The Venturimeter is an application of Bernoulli’s equation. Its basic principle also depends on Bernoulli’s equation that is velocity of fluid increases and pressure decreases.
Venturimeter’s principle was discovered by G.B. Venturi in his 1797, but this principle was taken into account in his 1887 with the help of C. Herschel. The principle is that as the cross-sectional area of the flow decreases, a pressure difference occurs between different flow regions, making it useful for measuring pressure differentials. This pressure difference can be used to easily measure emissions in a stream.
How Does Venturimeter Work?
Venturimeters work on Bernoulli’s principle, so let’s consider how we rely on Bernoulli’s principle.
According to the continuity equation, assuming that the volume of liquid entering the pipe, v1, corresponds to the volumetric flow at the inlet (Q1) to the outlet volumetric flow at the outlet (Q2), then at v1, the volume of water entering the pipe is A venturi counter at the inlet must discharge the same amount of water at the outlet, so v1/t1= v2/t2 in seconds.
The area of section 1 (according to the diagram above) is larger than that of section 2, which means that the reduced area means less pressure at the throttling and therefore less velocity. Increased to maintain flow (Q1=Q2 ).
At the throat position, the flow velocity is maximum and the pressure is minimum.
After throttling there is again a diverging cone (diffuser) to bring the pressure back as close as possible to its actual value.
This allows the volumetric flow rate to be easily determined using the U-tube manometer shown in the diagram above by finding the pressure difference between section 1 (retraction section) and section 2 (throat).
Venturimeter Equation
Venturimeter equation is given by:
Applications of Venturimeter
- As mentioned above, a venturimeter is used to measure the discharge in the flow tube.
- In medical applications, it is used to measure arterial flow velocity.
- There are other industrial applications such as gases, liquids and oils where pressure drop should be avoided.
- This device also measures liquid leaks containing dirt and dirt particles.