High Quality Auto Parts Diesel Fuel Injector 1465A054 095000-5760 Fuel Injector Engine Parts

Abstract
The turbulence characteristics at the injector nozzle outlet play a decisive role in the primary breakup and atomization of fuel sprays. Variations in turbulence intensity, vortex scale, and velocity fluctuations directly affect droplet size distribution, fuel–air mixing, and combustion efficiency. This study investigates the correlation between nozzle-exit turbulence features and atomized droplet size using computational fluid dynamics (CFD) simulations combined with experimental spray measurements.

1. Introduction
Efficient atomization is essential in modern diesel and gasoline direct injection systems to ensure complete combustion and reduced emissions. While nozzle geometry and injection pressure are widely studied, the turbulence properties at the nozzle exit remain a critical yet complex factor influencing spray quality. Understanding the mechanism by which turbulence modifies droplet size distribution is vital for optimizing injector design and combustion performance.

2. Methodology

• Numerical Simulation: A three-dimensional CFD model incorporating Reynolds-Averaged Navier–Stokes (RANS) turbulence models and cavitation dynamics was developed to predict velocity fluctuations and turbulent kinetic energy at the nozzle outlet.

• Spray Analysis: The Lagrangian particle tracking method coupled with breakup models (Kelvin–Helmholtz and Rayleigh–Taylor) was used to predict droplet formation.

• Experimental Validation: Phase Doppler Particle Analyzer (PDPA) and high-speed imaging measured droplet size distribution, spray penetration, and cone angle under different injection pressures and nozzle designs.

3. Results

• Turbulence intensity: Higher turbulence intensity at the nozzle outlet accelerated liquid ligament breakup, reducing Sauter Mean Diameter (D32) by 10–15%.

• Vortex structures: Small-scale vortices promoted finer atomization, while large coherent vortices induced uneven spray distribution and localized droplet clustering.

• Injection pressure: Increasing injection pressure enhanced turbulence intensity, leading to a broader droplet size distribution and improved air–fuel mixing.

4. Discussion
The findings reveal that turbulence acts as an energy transfer mechanism that destabilizes liquid jets, facilitating surface wave growth and ligament breakup. However, excessive turbulence may produce non-uniform droplet distributions, negatively impacting combustion stability. Optimizing nozzle design to generate controlled turbulence levels—through adjustments in hole diameter, inlet rounding, and sac geometry—can achieve a balance between fine atomization and uniform spray dispersion.

5. Conclusion
Turbulence characteristics at the nozzle outlet significantly influence fuel atomization droplet size distribution. Moderate turbulence intensity and well-distributed vortex structures promote smaller, more uniform droplets, improving combustion efficiency and reducing emissions. This study highlights the importance of turbulence-informed injector design for next-generation high-efficiency engines. Future research should integrate large eddy simulation (LES) approaches to capture detailed turbulence structures and their transient effects on spray formation.