Optimization of hydrofoil leading-edge geometry for delaying incipient cavitation using a CFD-GA approach.

Cavitation is a common phenomenon in hydraulic machinery, which brings negative impacts such as noise, vibration, performance drop and material damage into hydraulic turbomachinery. In engineering applications of pumps, the cavitation-free operation is an important issue. Incipient cavitation is the start of cavitation and also a standard to value the cavitation behavior of the pump unit. Improving the incipient cavitation is usually empirical and difficult to conduct.Although previous studies have proposed various geometric modifications and flow control strategies to mitigate cavitation, most approaches are either case-specific or involve trade-offs with hydraulic performance such as efficiency and head. In addition, many studies focus on reducing developed cavitation rather than delaying incipient cavitation, particularly under off-design conditions where pumps are more vulnerable. Furthermore, systematic optimization methods for leading-edge geometry remain limited, and existing approaches often rely on empirical design or local modifications without global search capability. Therefore, there is a need for an efficient and systematic optimization framework to improve incipient cavitation performance while maintaining acceptable hydraulic characteristics. In this study,a NACA0006 hydrofoil is employed as a simplified model to study the delay method of incipient cavitation for pump impellers. The optimization is conducted for specific large incidence angles by using a strategy combined genetic algorithm with computational fluid dynamics. The geometry of hydrofoil is searched in a given range to find a solution which has gentle pressure drop on leading edge separation region. After optimization, new optimized foil profile is found with higher minimum pressure than initial foil. Verified by experiment in cavitation tunnel, the optimized foil is found with a later incipient cavitation and smaller cavity scale than the initial foil at incidence angle around 5 degrees. Based on experimental and numerical analysis, the optimization brings a gentle geometry gradient to hydrofoil by setting target weight values. The optimized geometry causes gentler pressure gradient than initial foil to make the cavitation incepts later and smaller. Very slight changes are found on the Lift/Drag force ratio FL/FD which should be carefully checked before applying. For pumps, the optimization method can work to improve the cavitation behavior under off-design conditions and provide a wider cavitation-free operation region in engineering applications.