New High Quality Diesel Nozzle DSLA150P784 for Injection Nozzle Diesel Engine Parts

Abstract
In modern high-pressure fuel injection systems, the temperature field distribution within the injector nozzle plays a vital role in determining fuel viscosity, cavitation behavior, and spray atomization quality. Under high-pressure and high-frequency operation, strong interactions occur among fluid flow, structural deformation, and heat transfer, leading to complex transient thermal effects. This study establishes a fluid–structure–thermal coupling (FSTC) model to investigate the influence of the internal temperature field on the atomization characteristics of diesel injector nozzles.

Using Computational Fluid Dynamics (CFD) coupled with Finite Element Analysis (FEA), the transient flow, temperature, and stress fields were simultaneously solved under different injection pressures (100–250 MPa) and fuel temperatures (20–120 °C). The results revealed that local temperature gradients within the nozzle wall and orifice region significantly affect fuel density and viscosity, thereby altering the flow rate and spray cone angle. High wall temperatures near the orifice outlet intensified vapor formation and cavitation, while uneven heat distribution caused asymmetric spray patterns and reduced atomization uniformity.

The fluid–structure–thermal coupling analysis further demonstrated that structural expansion caused by localized heating can slightly modify the orifice diameter (on the order of micrometers), leading to measurable variations in spray momentum and penetration. Experimental validation using an infrared thermography system and high-speed Schlieren imaging confirmed the simulation predictions. A temperature increase of 50 °C was found to reduce fuel viscosity by 18% and increase the average spray cone angle by approximately 6°, enhancing atomization efficiency but also promoting transient cavitation.

To optimize thermal performance, design strategies such as thermal barrier coatings, improved cooling channel layouts, and optimized wall thickness ratios were proposed. Simulation results showed that uniform temperature distribution and effective heat dissipation improved spray uniformity by 15% and reduced cavitation intensity by 22%.

In conclusion, the study demonstrates that temperature field distribution within the injector nozzle is a key factor affecting atomization performance under coupled thermo-fluid-structural interactions. The proposed FSTC-based analysis provides a theoretical foundation for the thermal optimization and durability improvement of next-generation high-pressure injectors, enabling more efficient and cleaner combustion in advanced diesel engines.