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De Laval Nozzle Isentropic Supersonic Expansion Calculator

A convergent-divergent de Laval nozzle accelerates high-pressure, subsonic combustion chamber gas to sonic speed at the throat and supersonic velocities in the diverging bell.

Stagnation combustion chamber pressure.

Stagnation gas flame temperature.

Ratio of specific heats Cp/Cv for combustion products (typically 1.18 to 1.30).

Ratio of nozzle exit area to sonic throat area (> 1).

Calculated Result
Mach 3.28

Supersonic Exit Mach Number (Me)

Exit Static Pressure

0.6269 bar (62.69 kPa)

Exit Static Temperature

1446.0 K

Expansion Ratio (P₀/Pe)

79.8

Calculation Breakdown

  1. Step 1: Supersonic Area-Mach RelationAe / A* = 10 => Solved supersonic Mach Me = 3.28
  2. Step 2: Isentropic Static TemperatureTe = T₀ / [1 + ((γ-1)/2)·Me²] = 3000 / [1 + 0.10·3.28²] = 1446.0 K
  3. Step 3: Isentropic Static PressurePe = P₀ · (Te / T₀)^(γ / (γ - 1)) = 50 · (0.482)^6.00 = 0.6269 bar

What Is the De Laval Nozzle Isentropic Supersonic Expansion Calculator?

A de Laval nozzle is a hourglass-shaped tube used to accelerate hot pressurized gas into an energetic supersonic exhaust jet.

How Does the De Laval Nozzle Isentropic Supersonic Expansion Calculator Work?

Iteratively solves the non-linear supersonic branch of the area-Mach relation.

Computes static temperature Te using isentropic temperature ratio.

Computes static exit pressure Pe using isentropic pressure ratio.

De Laval Nozzle Isentropic Supersonic Expansion Calculator Formula & Variables

The core mathematical equation utilized by this calculator is expressed as:

(Ae/A*)² = (1/Me²) · [ (2/(γ+1)) · (1 + ((γ-1)/2)·Me²) ]^((γ+1)/(γ-1))

1D isentropic area-Mach equation solved for the supersonic exit flow branch.

How to Use the De Laval Nozzle Isentropic Supersonic Expansion Calculator

  1. Enter chamber pressure P₀ and flame temperature T₀.
  2. Input gas specific heat ratio γ and nozzle area expansion ratio Ae/A*.

Step-by-Step Example Calculation

Rocket Engine Sea-Level Bell Nozzle

Input Values:

chamberPressure:50
chamberTemperature:3000
gamma:1.2
areaRatio:10
Worked Steps: 50 bar chamber expanding through 10:1 area ratio nozzle.

Understanding Your Result

Primary output indicates supersonic exit Mach number.

Summary displays static exit pressure and temperature.

Factors That Affect the Result

  • Area ratio (higher Ae/A* produces higher Mach and lower exit pressure).
  • Ambient atmospheric pressure (governs over-expanded vs under-expanded flow).

When Should You Use This Calculator?

  • Rocket engine nozzle design, wind tunnel supersonic test sections, and steam turbines.

Assumptions & Limitations

  • Assumes steady, 1D, inviscid, isentropic ideal gas flow with frozen chemistry.

Frequently Asked Questions

Calculation Accuracy & Reference Note

Standard compressible fluid dynamics formulation.

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