What Is the Combustion Equivalence Ratio & Lambda Calculator?
The equivalence ratio φ indicates whether a fuel-air mixture contains exactly enough oxygen for combustion, excess fuel, or excess air.
How Does the Combustion Equivalence Ratio & Lambda Calculator Work?
Divides stoichiometric AFR by actual operating AFR.
Inverts φ to determine automotive lambda λ.
Classifies the combustion regime (rich, lean, or stoichiometric).
Combustion Equivalence Ratio & Lambda Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
φ = AFR_stoich / AFR_actual, λ = 1 / φ = AFR_actual / AFR_stoich
Standard definitions of equivalence ratio φ and oxygen lambda sensor factor λ.
How to Use the Combustion Equivalence Ratio & Lambda Calculator
- Enter actual air-fuel ratio from wideband oxygen sensor telemetry.
- Specify fuel stoichiometric ratio.
Step-by-Step Example Calculation
Gasoline Engine Stoichiometric Point
Input Values:
actualAFR:14.7
stoichAFR:14.7
Worked Steps: Perfect stoichiometric combustion at AFR 14.7:1 (φ = 1.0, λ = 1.0).
Understanding Your Result
φ = 1.0 (λ = 1.0): Stoichiometric.
φ > 1.0 (λ < 1.0): Fuel-Rich.
φ < 1.0 (λ > 1.0): Fuel-Lean.
Factors That Affect the Result
- Fuel chemical composition (carbon-to-hydrogen ratio).
When Should You Use This Calculator?
- Engine tuning, emissions compliance, and burner flame stability.
Assumptions & Limitations
- Based on mass flow ratios.
Frequently Asked Questions
Calculation Accuracy & Reference Note
Standard combustion engineering definitions.