On the Critical Condition for Flame Acceleration in Hydrogen-Based Mixtures

Area of Science:

• Combustion science
• Chemical engineering
• Numerical modeling

Background:

• Flame acceleration in hydrogen-based fuels is a critical safety concern.
• Accurate prediction of concentration limits is essential for safe hydrogen energy systems.

Purpose of the Study:

• To develop and validate a novel numerical approach for estimating concentration limits of flame acceleration.
• To identify the physical mechanisms driving the transition from steady to accelerated flame propagation.

Main Methods:

• Numerical simulations of hydrogen-air and hydrogen-oxygen flames in channels.
• Quantitative analysis of simulation results to determine concentration limits.
• Investigation of flame-boundary layer interactions and heat transfer dynamics.

Main Results:

• Identified 11 ± 0.25% hydrogen as the lean concentration limit for flame acceleration, matching experimental data.
• Distinguished the physical mechanism of flame acceleration involving flame stretching and competing heat transfer effects.
• Validated the numerical technique against existing experimental findings.

Conclusions:

• The novel numerical technique provides accurate estimation of flame acceleration limits.
• Understanding the mechanism is key for mitigating risks in hydrogen energy applications.
• The method is applicable to optimizing combustors and assessing risks in hydrogen infrastructure.