It consists of three parts.
- A short converging part
- Diverging part
It is based on the principle of Bernoulli’s equation. Inside of the venturimeter pressure difference is created by reducing the cross-sectional area of the flow passage. The pressure difference is measured by using a differential U-tube manometer. This pressure difference helps in the determination of rate of flow of fluid or discharge through the pipe line. As the inlet area of the venturi is large than at the throat, the velocity at the throat increases resulting in decrease of pressure. By this, a pressure difference is created between the inlet and the throat of the venturi.
D1 and D2 — Diameter at inlet and throat respectively
P1and P2 — Pressure at inlet and throat
V1 and V2 — Velocity at inlet ad throat