Natural gas is not commonly used in compression ignition cycles due to difficulty in achieving autoignition conditions. The addition of hydrogen to natural gas can help overcome this issue considering hydrogen’s flammability range and ability to autoignite. In this computational study, the turbulent injection of hydrogen-methane mixtures with varied composition of the gaseous fuels into a constant volume combustion chamber has been modeled. All conditions including injection pressure, initial chamber temperature, and initial chamber pressure are kept constant; the jet properties and combustion characteristics were then investigated. The results indicate that adding hydrogen to methane drastically shortens the ignition delay, enables the system to run at a lower initial temperature, and provides appropriate conditions for the compression ignition of the gaseous fuel. Increasing the volume fraction of hydrogen in the mixture strongly affects the spray tip penetration length and cone angle, while altering the mixing rate of the injected fuel with air. The mixtures with higher hydrogen volume fractions penetrate more during the early stages of injection. However, the higher momentum of the mixtures with more methane compensates for this effect when the jet disperses significantly in the chamber.
Numerical Study of Spray Characteristics of n-Heptane in Constant Volume Combustion Chamber under Diesel Engine Conditions
