How is nozzle throat area calculated for incompressible flow?

A_t = Q / (Cd × √(2ΔP/ρ)), where Q is volumetric flow rate (m³/s), Cd is discharge coefficient (0.95–0.99 for ASME long-radius nozzles), ΔP is differential pressure (Pa), and ρ is fluid density (kg/m³). Per ISO 5167-3 for flow nozzles.

What is choked flow in a nozzle?

Choked flow occurs when the throat velocity reaches the speed of sound (Mach 1). For air, this happens when the upstream-to-downstream pressure ratio P_d/P_u ≤ 0.528. Beyond choked conditions, the flow rate is independent of downstream pressure and equals ṁ_choked = A_t × P_u × √(γ/R_g T_u) × (2/(γ+1))^((γ+1)/(2(γ-1))).

Nozzle Throat Area Calculator

Calculate the throat area and discharge coefficient of flow nozzles for subsonic and choked flow conditions in compressible and incompressible fluids.

2D stress state at a point. All stresses in MPa.

σx — Normal Stress X (MPa)

σy — Normal Stress Y (MPa)

τxy — Shear Stress (MPa)

⚙ Mechanical Note: Results are based on standard textbook formulas and ISO/AASHTO references. Always verify critical designs with applicable codes (ISO 898, AASHTO 1993, AISC, Eurocode 3) and a qualified engineer.

How to Use

Enter the values for the patient or scenario you are assessing. Calculate the throat area and discharge coefficient of flow nozzles for subsonic and choked flow conditions in compressible and incompressible fluids. Use the nozzle throat area result to inform your clinical assessment.

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Frequently Asked Questions

How is nozzle throat area calculated for incompressible flow?

What is choked flow in a nozzle?