New High Quality Diesel Nozzle DN0PD619 for Injection Nozzle Diesel Engine Parts

Abstract
The internal flow characteristics of injector nozzles have a direct influence on spray atomization, fuel–air mixing, and combustion efficiency in diesel engines. Traditional smooth-channel designs face limitations in reducing hydraulic resistance and enhancing atomization quality. Inspired by natural non-smooth surface structures such as shark skin riblets and lotus leaf textures, this study proposes a bionic non-smooth design strategy for injector nozzle flow channels. Computational fluid dynamics (CFD) simulations and experimental validation are employed to evaluate drag reduction and atomization enhancement effects.

1. Introduction
Fuel injectors are critical in modern engines, where nozzle flow directly affects combustion stability, emissions, and thermal efficiency. Conventional nozzle designs with smooth internal surfaces often suffer from flow separation, cavitation, and excessive energy loss, which limit spray atomization. Bionic non-smooth structures, observed in natural organisms that evolve surface morphologies for fluid control, provide a promising solution to reduce flow resistance and improve spray breakup quality.

2. Methodology

• Bionic design: Several non-smooth structures inspired by biological surfaces were designed, including micro-grooves, dimples, and riblet arrays.

• Numerical simulation: CFD models incorporating cavitation and turbulence models simulated fuel flow, pressure distribution, and spray development under high injection pressures (up to 200 MPa).

• Experimental validation: High-speed imaging and phase Doppler particle analysis (PDPA) measured spray cone angle, droplet size distribution, and penetration length to confirm simulation accuracy.

3. Results

• Drag reduction: Non-smooth structures effectively suppressed boundary layer separation and reduced wall shear stress, lowering pressure losses by 8–12% compared with smooth channels.

• Atomization enhancement: Micro-grooved surfaces promoted small-scale turbulence and cavitation inception, which facilitated spray breakup and reduced mean droplet diameter (D32) by approximately 10%.

• Spray characteristics: Modified nozzles exhibited larger spray cone angles and more uniform droplet size distribution, leading to improved fuel–air mixing.

4. Discussion
The results demonstrate that bionic non-smooth structures provide a dual benefit: reducing hydraulic resistance while simultaneously enhancing spray atomization. Unlike conventional surface roughening, which may increase friction losses, carefully designed riblets and dimples stabilize near-wall flow and generate controlled vortices, promoting efficient breakup. However, structural parameters such as groove depth and spacing must be optimized to balance drag reduction and atomization effects.

5. Conclusion
This study confirms that the application of bionic non-smooth structures to injector nozzle flow channels can significantly reduce drag and enhance atomization. By integrating CFD simulations with experimental validation, the proposed design strategy demonstrates potential for improving combustion efficiency and lowering emissions in advanced diesel engines. Future work will focus on multi-hole nozzle applications and optimization of geometric parameters for practical engine conditions.