New High Quality Diesel Nozzle DLLA158P844 for Injection Nozzle Diesel Engine Parts

Abstract
The multi-hole injector nozzle plays a decisive role in fuel atomization, spray penetration, and the spatial distribution of the fuel-air mixture. Inconsistent flow distribution among nozzle holes leads to uneven spray formation, which directly impacts combustion efficiency, ignition stability, and emission performance. This paper investigates the mechanisms linking flow distribution uniformity with combustion characteristics and highlights strategies to improve nozzle design and system integration.

1. Background and Significance
Modern engines rely on high-pressure common rail injection systems, where multi-hole nozzles are widely applied to achieve precise fuel delivery and optimized spray patterns. Ideally, each hole should deliver an identical fuel mass per injection cycle to ensure symmetric spray dispersion. However, variations in hole geometry, machining tolerances, needle lift dynamics, and cavitation phenomena often cause significant deviations in effective flow rates. Such non-uniformity disrupts mixture preparation, resulting in cycle-to-cycle variations and increased pollutant formation.

2. Flow Distribution Mechanisms
The non-uniform distribution arises mainly from three factors:

• Geometric asymmetry: Even micrometer-level differences in hole diameter or orientation can produce noticeable flow imbalance.

• Needle motion effects: At low lift, fuel prefers certain paths due to local hydrodynamic resistance differences, aggravating uneven flow.

• Cavitation and turbulence: Unequal cavitation development at different holes alters discharge coefficients, further disturbing uniformity.

These flow field imbalances ultimately shape spray penetration length, droplet size distribution, and spray cone angle, all of which influence in-cylinder mixture formation.

3. Influence on Combustion Characteristics
Flow maldistribution leads to uneven fuel-air ratios across different regions of the combustion chamber:

• Ignition delay variability: Richer sprays ignite earlier, while leaner regions show longer ignition delays, increasing combustion instability.

• In-cylinder turbulence interaction: Uneven spray penetration disrupts intended swirl or tumble motion, weakening turbulence-chemistry coupling.

• Soot and NOx trade-off: Regions with locally rich mixtures promote soot formation, whereas over-lean areas may increase NOx due to higher local temperatures.

• Cycle-to-cycle variation: Fluctuating local mixture properties reduce overall combustion repeatability, leading to efficiency losses.

4. Optimization Approaches
Improving flow distribution uniformity involves both nozzle design and injection system integration:

• Hole geometry refinement: Precise control of hole diameter, length-to-diameter ratio, and inclination angle reduces geometric imbalance.

• Symmetric needle seating: Ensuring concentricity between the needle and nozzle sac volume minimizes preferential flow.

• CFD-based optimization: Computational fluid dynamics enables detailed analysis of internal flow structures, allowing prediction of cavitation and flow coefficients at each hole.

• Advanced manufacturing methods: Laser drilling and EDM (electrical discharge machining) with high precision can ensure tighter hole tolerances and consistency.

• Closed-loop control strategies: Real-time injection monitoring combined with adaptive control may compensate for slight variations during operation.

5. Conclusion
Flow distribution uniformity of multi-hole injector nozzles is a critical determinant of engine combustion quality. Non-uniform fuel delivery leads to unstable ignition, higher emissions, and reduced thermal efficiency. By combining advanced nozzle design, precision manufacturing, and CFD-guided optimization, it is possible to significantly enhance spray homogeneity, thereby achieving stable combustion and cleaner emissions. Future work should focus on the integration of flow distribution metrics into engine control algorithms, ensuring robust performance across a wide range of operating conditions.