Venturi Meter Calculator
Determine the flow rate through a Venturi meter from upstream and throat dimensions and pressure difference.
Vazão Volumétrica
10.89 L/s
Volumetric Flow Rate vs Discharge Coefficient (Cd)
Formula
## Venturi Meter Flow Measurement A Venturi meter uses a converging-diverging section to measure flow with minimal permanent pressure loss. ### Formula **Q = Cd A2 sqrt(2 delta_P / (rho (1 - beta^4)))** where A2 is the throat area, beta = D2/D1 is the diameter ratio, and the (1 - beta^4) term accounts for the velocity change between upstream and throat. Cd for Venturi meters is typically 0.95-0.99.
Exemplo Resolvido
A Venturi with 100 mm upstream and 50 mm throat, 15 kPa differential, water.
- 01beta = 50/100 = 0.5, beta^4 = 0.0625
- 02A2 = pi x 0.05^2 / 4 = 0.001963 m^2
- 03sqrt(2 x 15000 / (1000 x (1 - 0.0625))) = sqrt(30000/937.5) = sqrt(32) = 5.657 m/s
- 04Q = 0.98 x 0.001963 x 5.657 = 0.01088 m^3/s = 10.88 L/s
Perguntas Frequentes
Why is the Venturi Cd higher than for an orifice?
The smooth converging-diverging shape of a Venturi minimises flow separation and turbulence losses, so the actual flow is much closer to the theoretical (ideal) value. Cd is typically 0.95-0.99 vs 0.60-0.65 for orifices.
What is the advantage over an orifice plate?
Venturi meters recover about 80-95% of the differential pressure, resulting in much lower permanent pressure loss. They are preferred in large systems where pumping energy is expensive.
What beta ratio is optimal?
Beta ratios between 0.4 and 0.75 are common. Lower beta gives higher sensitivity but more pressure drop. The optimal choice balances measurement accuracy against allowable permanent loss.
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