Nozzle Discharge Calculator

What is a Nozzle?

A nozzle is a converging device that accelerates fluid by reducing cross-sectional area, converting pressure energy to kinetic energy. Nozzles appear in fire hoses, garden sprinklers, jet pumps, rocket engines, and hydraulic test equipment.

Nozzle Flow Formula

Q = Cd × A_nozzle × √(2 × ΔP / ρ)

Or using upstream head: Q = Cd × A × √(2gh)

Exit velocity: v = Cv × √(2gh) where Cv ≈ 0.98 for a well-formed converging nozzle.

Discharge coefficient Cd = Cc × Cv, where Cc = vena contracta coefficient (≈1.0 for a nozzle, as there's no contraction, unlike an orifice).

For nozzles: Cd ≈ 0.95–0.99 (higher than orifice plates' 0.6).

Practical Examples

Example 1 — Fire hose nozzle: 25mm diameter, supply pressure 7 bar (700,000 Pa), Cd = 0.97, water. v = 0.97 × √(2 × 700,000/1000) = 0.97 × 37.4 = 36.3 m/s. Q = π×0.0125² × 36.3 = 17.8 L/s = 1,068 L/min.

Example 2 — Garden sprinkler: 5mm nozzle, 3 bar pressure. v = √(2 × 300,000/1000) = 24.5 m/s. Q = π×0.0025² × 24.5 = 0.48 L/s = 29 L/min.

Applications

Nozzles are critical in: fire suppression systems, spray drying, hydraulic cleaning, dust suppression, fuel injection, and jet pump design.