Effect of thermodynamic modeling and design variations on cavitation erosion in high-pressure fuel injectors

Preprint, 2025

The influence of thermodynamic modeling and needle design variations on cavitation erosion in high- pressure fuel injectors was investigated. Two thermodynamic frameworks—a barotropic Tait equation of state with incompressible vapor (Tait&IV) and a real-fluid PC-SAFT model with compressible vapor (PC-SAFT&CV)—were assessed. The modeling approach was validated against experimental erosion data obtained from a single-hole injector operating under industrial conditions. Cavitation behavior and erosion risk were evaluated using a unified indicator based on the squared material derivative of pressure. Following validation, three different needle-tip geometries (Base, NV-01, and NV-02) were studied using the PC-SAFT&CV model. The results showed that both thermodynamic assumptions and geometric features strongly influenced vapor collapse patterns, erosion location, and thermal gradients. The PC-SAFT&CV model provided improved agreement with experimental erosion locations and predicted smaller, more localized vapor structures. Among the designs, NV-02 yielded the most balanced erosion profile and reduced vapor volume by 85%. These findings demonstrate the importance of combining advanced thermodynamic models with design optimization to improve erosion prediction and enhance injector durability under realistic conditions.