LEE- Gemi İnşaatı ve Gemi Makinaları Mühendisliği Lisansüstü Programı

Bu topluluk için Kalıcı Uri

http://hdl.handle.net/11527/19282

Gözat

Yazar "Delikan, Mehmet" ile LEE- Gemi İnşaatı ve Gemi Makinaları Mühendisliği Lisansüstü Programı'a göz atma
  • Öge
    Computational analysis of 2-d foils with and without ground effect in tandem
    (Graduate School, 2024-12-26) Delikan, Mehmet ; Bal, Şakir ; 508221003 ; Naval Architecture and Marine Engineering
    The flow behavior around tandem foils, both with and without ground effect, remains a complex and significant area of study, particularly as it plays a critical role in the design and development of wing-in-ground effect vehicles, sailing yachts, and hydrofoil vessels. Most existing numerical and experimental research on tandem configurations has been conducted at high Reynolds numbers exceeding 10⁶. In this comprehensive parametric study, the 2-D flow around two tandem NACA 4412 foils is simulated under both ground effect and free-flow conditions at a moderate Reynolds number of (Re = 3 × 10⁵). The angle of attack is fixed at 4° for both foils, and the effects of stagger distance (S), gap height (G), and ground clearance (H) are systematically investigated to assess their influence on the aero/hydrodynamic characteristics of the tandem system. The analysis begins by validating the aero/hydrodynamic performance of a single NACA 4412 foil without ground effect, followed by validation with ground effect. This step ensures the robustness of the computational framework before extending the analysis to tandem configurations. The incompressible RANS equations are solved using the finite-volume method, employing the SST k-ω turbulence model, which includes the γ-transport equation for enhanced turbulence modeling. This methodology enables a detailed examination of flow structures, pressure distributions, and the overall interaction between the foils in tandem arrangements under varying geometrical configurations. The results demonstrate that, consistent with findings from higher Reynolds number studies, tandem foils exhibit improved hydrodynamic efficiency compared to isolated foils, particularly when the gap height is positive, i.e., when the fore foil is positioned above the aft foil. Ground effect improves the aero/hydrodynamic performance of both isolated and tandem foils by enhancing lift and reducing drag. This phenomenon results in superior performance metrics compared to configurations operating outside of ground effect. In the tandem arrangement, the presence of the aft foil reduces drag on the fore foil due to increased static pressure between the foils, effectively exerting an upstream force on the fore foil. Conversely, the aft foil experiences an increase in drag due to the influence of the fore foil, a phenomenon observed across most tested configurations, with variations depending on stagger and gap distances. The interference effects between the tandem foils produce a range of outcomes; depending on the spacing, these effects can be either favorable or unfavorable in terms of drag reduction and overall aerodynamic performance. The effect of ground clearance on tandem foil configurations exhibits a similar trend to its influence on isolated foils in ground effect, characterized by an increase in both lift and drag coefficients as ground clearance decreases. These findings suggest that optimized tandem configurations can achieve significantly enhanced lift-to-drag ratios, particularly under positive gap heights, offering potential for performance improvements in wing-in-ground effect vehicles and other marine and aerospace applications. This research provides novel insights into the hydrodynamics of tandem foils operating at moderate Reynolds numbers in both ground-effect and out-of-ground-effect conditions. The outcomes of this investigation contribute to the ongoing development of next-generation wing-in-ground effect craft, hydrofoil systems, and other high-performance applications where tandem foil configurations can be utilized.