doi: 10.52899/24141437_2026_01_5
UDK: 531.391.1:532.5.011

Numerical Study of the Effect of Slot Position on the Hydrodynamic Characteristics of NACA 4412 at High Angles of Attack

Мамдух А. Р., Чжоу И. ., Фу Ш. .
Article language:
Citation Link: Ali Rami Mamdouh, Zhou Yi, Fu Shuang. Numerical Study of the Effect of Slot Position on the Hydrodynamic Characteristics of NACA 4412 at High Angles of Attack. Transactions of the Saint Petersburg State Marine Technical University. 2026;5(1):5–16. DOI: https://doi.org/10.52899/24141437_2026_01_5 EDN: LOLSZS

Annotation

BACKGROUND: The separation of the flow on the bearing surfaces of marine equipment leads to a loss of lift, increased resistance and vibration, reducing efficiency and safety. Passive slit profiles make it possible to delay stall without energy consumption, however, the effect of the slit position along the chord at high Reynolds numbers has not been sufficiently studied. AIM: To determine the slot position that ensures delayed flow separation, improved lift-to-drag performance, and an increased stall angle, as well as to formulate practical recommendations for designing high-performance hydrofoils for marine engineering applications. METHODS: This numerical study investigates the effect of slot position along the chord on the aerodynamic characteristics of the NACA 4412 airfoil at a high Reynolds number (Re = 3.1 × 10⁶). Using the Reynolds-averaged Navier–Stokes equations with the k–ω SST turbulence model, five slot configurations located between 0.3 C and 0.5 C were analyzed. The numerical methodology was validated against well-established experimental data. RESULTS: It was shown that an optimally positioned slot can remarkably improve performance at high angles of attack by suppressing flow separation. The optimal configuration, with the slot located at a distance of 0.4 C from the leading edge of the body, provided the most substantial improvements, including a 7° delay in stall angle and an approximately 43% increase in the maximum lift coefficient. CONCLUSION: This study confirms that passive flow control using a slot, particularly at the 0.4 C chord position, represents a promising design approach for enhancing aerodynamic efficiency and improving stall characteristics of airfoils used in marine engineering applications. Keywords: flow control; slotted airfoil; NACA 4412; RANS; CFD; flow separation; stall delay.

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