Ignition Dynamics in Diesel Spray Combustion

Ignition dynamics in diesel spray combustion encompass the sequence of physical and chemical processes by which liquid fuel injected into a high-pressure, high-temperature environment undergoes atomisation, evaporation, mixing and subsequent auto-ignition. The onset of ignition is characterised by a two-stage process: an initial low-temperature chemistry (LTC) regime that produces intermediate species such as formaldehyde, followed by a high-temperature chemistry (HTC) regime that drives rapid heat release and flame propagation. Key macroscopic metrics include the ignition delay time, which governs combustion phasing and efficiency, and the lift-off length, which reflects flame stability and pollutant formation. Turbulent mixing, vaporisation rates and local scalar dissipation rates critically influence these metrics, with slender jets, cavitation-enhanced sprays and exhaust gas recirculation each modifying ignition behaviour. Advances in experimental diagnostics—such as high-speed laser-induced fluorescence and schlieren imaging—and in computational approaches like large-eddy simulation coupled with detailed or reduced chemistry (for example using flamelet generated manifold methods) have deepened understanding of the interplay between turbulent structure, mixing and chemistry. Application of these insights is vital for optimising modern diesel engines to meet stringent emissions regulations, to reduce soot and nitrogen oxide formation and to guide the introduction of alternative fuels and dual-fuel strategies.

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Ignition Dynamics in Diesel Spray Combustion publication trend

The graph below shows the total number of articles in ignition dynamics in diesel spray combustion across all publications each year (not limited to Nature Index journals).

Technical terms

Ignition delay time (IDT): Interval between start of injection and onset of rapid heat release.

Lift-off length (LOL): Distance from injector tip to the location where a stable flame front forms.

Low-temperature combustion (LTC): Initial stage of oxidation producing intermediate species under cooler conditions.

High-temperature combustion (HTC): Rapid oxidation stage marked by sharp heat release and flame propagation.

Large-eddy simulation (LES): Computational method resolving large turbulent structures while modelling subgrid scales.

Flamelet Generated Manifold (FGM): Reduced-chemistry technique precomputing flame structures under varying strain rates.

References

1. Large-eddy simulation of dual-fuel spray ignition at varying levels of methane diluted ambient oxidizer using FGM. Fuel (2023).
2. A comparative study on methanol and n-dodecane spray flames using Large-Eddy Simulation. Combustion and Flame (2024).
3. Large eddy simulation of n-dodecane spray flame: Effects of injection pressure on spray combustion characteristics at low ambient temperature. Proceedings of the Combustion Institute (2023).
4. Detailed measurements of transient two-stage ignition and combustion processes in high-pressure spray flames using simultaneous high-speed formaldehyde PLIF and schlieren imaging. Proceedings of the Combustion Institute (2021).
5. The inclusion of scalar dissipation rate in modeling of an n -dodecane spray flame using flamelet generated manifold. Combustion and Flame (2023).
6. Large Eeddy Simulation of cavitation effects on reacting spray flames using FGM and a new dispersion model with multiple realizations. Combustion and Flame (2022).
7. Large Eddy Simulation of Spray Auto-ignition Under EGR Conditions. Flow, Turbulence and Combustion (2015).