1. What is the Air Specific Heat Ratio?

Definition: The specific heat ratio (γ) is the ratio of specific heat at constant pressure (c_p) to specific heat at constant volume (c_v).

Purpose: This ratio is crucial in thermodynamics for calculating properties in isentropic processes and analyzing compressible flows.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( \gamma \) — Specific heat ratio (dimensionless)
• \( c_p \) — Specific heat at constant pressure (J/kg·K)
• \( c_v \) — Specific heat at constant volume (J/kg·K)

Explanation: For dry air at standard conditions, γ is approximately 1.4. This value changes with temperature and composition.

3. Importance of Specific Heat Ratio

Details: The ratio is essential in calculating:

• Speed of sound in air
• Isentropic flow properties
• Thermodynamic cycle analysis
• Compressible flow calculations

4. Using the Calculator

Tips: Enter the specific heat values (defaults are for dry air at 20°C: c_p = 1005 J/kg·K, c_v = 718 J/kg·K). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the typical γ value for air?
A: For dry air at standard conditions, γ ≈ 1.4. For moist air, it's slightly lower.

Q2: How does temperature affect γ?
A: γ decreases slightly with increasing temperature as vibrational modes become active.

Q3: What are c_p and c_v for common gases?
A: Air: 1005/718, Nitrogen: 1040/743, Oxygen: 919/659 (all in J/kg·K at 20°C).

Q4: Why is γ always greater than 1?
A: Because c_p is always greater than c_v (it includes work done during expansion).

Q5: How is γ used in speed of sound calculations?
A: Speed of sound \( a = \sqrt{\gamma R T} \), where R is gas constant and T is temperature.