Diesel Spray Dynamics in Combustion Systems

Diesel spray dynamics in modern combustion systems governs the atomisation of fuel under high-pressure and high-temperature conditions, which in turn dictates evaporation, mixing, ignition and ultimately engine performance and emissions. At pressures exceeding 200 MPa, liquid jets emerging from micrometre-scale nozzles undergo primary breakup into ligaments and droplets through aerodynamic and hydrodynamic instabilities. The transient evolution of spray tip penetration and cone angle modulates local equivalence ratios and thereby influences the onset of ignition delay and flame lift-off. Advanced optical diagnostics—including high-speed imaging, X-ray phase-contrast and schlieren techniques—combined with computational fluid dynamics have elucidated the interplay between nozzle geometry, cavitation, shock-wave formation and droplet distribution. Insight into these mechanisms is crucial for optimising combustion efficiency, reducing particulate and NOx emissions, and enabling the use of alternative fuels in engines worldwide.

Research from Nature Portfolio

Recent investigations have elucidated the macro characteristics and shock-wave configurations in supersonic diesel sprays. Using high-speed imaging and schlieren techniques, researchers demonstrated that sprays entering the supersonic regime generate oblique shock waves whose angles and spray-front cone geometry vary systematically with Mach number. Measurements of mean droplet diameter and comparisons with empirical models highlighted the critical role of aerodynamic instabilities in predicting spray breakup length and downstream droplet size distributions in transonic and supersonic flows.

Diesel Spray Dynamics in Combustion Systems publication trend

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

Technical terms

Atomisation: Process by which a continuous liquid jet disintegrates into droplets under aerodynamic and hydrodynamic forces.

Breakup length: Distance from the nozzle at which the coherent liquid core begins to fragment into ligaments and droplets.

Spray tip penetration: Maximum axial distance travelled by the leading edge of the spray plume from the nozzle exit.

Equivalence ratio: Local ratio of fuel to air compared with the stoichiometric ratio for complete combustion.

Ignition delay: Time interval between the start of fuel injection and the onset of self-sustained combustion.

Schlieren imaging: Optical technique that visualises spatial gradients in gas density by refracting light through a transparent medium.

Shock wave: Thin region of abrupt pressure, temperature and density change generated when the spray velocity exceeds the local speed of sound.

References

1. Parameter sensitivity analysis for diesel spray penetration prediction based on GA-BP neural network. Energy and AI (2024).
2. Experimental investigation on the characteristics of supersonic fuel spray and configurations of induced shock waves. Scientific Reports (2017).
3. Experimental Study on the Spray Characteristics of Diesel and Hydrotreated Vegetable Oil (HVO) Fuels under Different Injection Pressures. Processes (2024).
4. Interpretative Review of Diesel Spray Penetration Normalized by Length and Time of Breakup (Similarity Law of Diesel Spray and Its Application). Energies (2022).