Compressible Flow Calculator (Nozzles & Choked Flow)

Calculate critical flow parameters for compressible gases through nozzles, including choked flow conditions. Supports isentropic flow, ideal gas behavior, and various nozzle configurations.

Gas Type:

Inlet Pressure (P₀):

Inlet Temperature (T₀):

Molecular Weight (M):

kg/kmol

Back Pressure (P_b):

Nozzle Type:

Throat Area (A*):

Calculate:

Results

Critical Pressure Ratio (P*/P₀): –

Critical Temperature Ratio (T*/T₀): –

Critical Density Ratio (ρ*/ρ₀): –

Mass Flow Rate (ṁ): – kg/s

Exit Mach Number (Mₑ): –

Exit Pressure (Pₑ): – kPa

Exit Temperature (Tₑ): – K

Choked Flow: –

Velocity at Throat (V*): – m/s

About Compressible Flow in Nozzles

Compressible flow through nozzles is a fundamental concept in fluid dynamics, particularly important in applications like rocket engines, gas turbines, and HVAC systems. When a compressible fluid flows through a converging or converging-diverging nozzle, it can reach sonic velocity (Mach 1) at the throat under certain conditions, known as choked flow.

Key Concepts:

Choked Flow: Occurs when the flow velocity at the nozzle throat reaches Mach 1, limiting the maximum mass flow rate.
Critical Pressure Ratio: The pressure ratio (P*/P₀) at which choked flow occurs, dependent on the specific heat ratio (γ).
Isentropic Flow: Assumes the flow is adiabatic and reversible, with constant entropy.
De Laval Nozzle: A converging-diverging nozzle that can accelerate flow to supersonic velocities.

Formulas Used:

Critical Pressure Ratio: P*/P₀ = (2/(γ+1))^(γ/(γ-1))

Critical Temperature Ratio: T*/T₀ = 2/(γ+1)

Mass Flow Rate: ṁ = ρ₀ * A* * V* = P₀ * A* * sqrt(γ/(R*T₀)) * (2/(γ+1))^((γ+1)/(2(γ-1)))

Isentropic Relations: P/P₀ = (1 + (γ-1)/2 * M²)^(-γ/(γ-1))