1. What is an Isentropic Flow Calculator?

Definition: This calculator computes the isentropic pressure ratio (stagnation to static pressure) for compressible flow using the Mach number and specific heat ratio.

Purpose: It helps aerodynamics engineers and students analyze compressible flow conditions in nozzles, diffusers, and around aerodynamic bodies.

2. How Does the Calculator Work?

The calculator uses the isentropic flow relation:

Where:

• \( P_0/P \) — Stagnation to static pressure ratio (dimensionless)
• \( \gamma \) — Specific heat ratio (~1.4 for air)
• \( M \) — Mach number (dimensionless)

Explanation: The formula relates the stagnation pressure (total pressure) to static pressure through an isentropic process as a function of Mach number.

3. Importance of Pressure Ratio Calculation

Details: Pressure ratio is fundamental in compressible flow analysis, affecting thrust calculations, nozzle design, and shock wave analysis.

4. Using the Calculator

Tips: Enter the specific heat ratio (default 1.4 for air) and Mach number (must be ≥ 0). For subsonic and supersonic flows, the calculator remains valid.

5. Frequently Asked Questions (FAQ)

Q1: What is the specific heat ratio (γ)?
A: It's the ratio of specific heats (cp/cv), approximately 1.4 for air at standard conditions.

Q2: What does P₀/P = 1 mean?
A: It means the flow is at rest (M = 0), so stagnation and static pressures are equal.

Q3: How does pressure ratio change with Mach number?
A: The ratio increases rapidly with Mach number, especially in supersonic flow.

Q4: Is this valid for hypersonic flows?
A: The formula is mathematically valid, but real hypersonic flows may have additional effects like dissociation.

Q5: What's the pressure ratio at M = 1?
A: For γ = 1.4, P₀/P ≈ 1.893 at Mach 1 (sonic condition).