Abstract
The correlation between computational fluid dynamics (CFD) and experimental fluid dynamics (EFD) is crucial for the behavior prediction of aerodynamic bodies. This paper’s objective is twofold: (1) to develop a method that approaches commercial CFD codes and their link with EFD in a more efficient way, using a downscaled model, and (2) to investigate the effect of rain on the aerodynamic behavior of a wing. More specifically, we investigate the one-phase and two-phase flow over a typical wing section NACA 641-212 airfoil, in the commercial code Ansys Fluent. Two computational models were developed; the first model represents the original dimensions of the wing, while the second is downscaled to 23% of the original. The response of the models in air and air–water flow were primarily studied, as well as the impact on aerodynamic efficiency due to the existence of the second phase. For the computational fluid dynamics simulations, a pressure-based solver with a second-order upwind scheme for the spatial discretization and the Spalart–Allmaras (SA) turbulence model were utilized. Meanwhile, for the two-phase flow of air–water, the discrete phase model (DPM) with wall–film boundary conditions on the surface of the wing and two-way coupling between continuous and discrete phase was considered. The second phase was simulated as water droplets injected in the continuous phase, in a Euler–Lagrange approach. The experimental model was constructed in accordance with the downscaled model and tested in a subsonic wind tunnel, using 3D printing technology which reduced the experiment expenses. The presence of water in two-phase flow was proven to deteriorate the aerodynamic factors of the wing compared to one-phase flow, as expected. The three-stage comparison of CFD and EFD results showed a very good convergence, in both single and two-phase flow. This can lead to the conclusion that a rapid and low-cost study for the estimation of the aerodynamic performance of objects with high accuracy is feasible with the suggested method.
Highlights
Today, it is commonly known that, in the field of fluid mechanics, computational fluid dynamics (CFD) codes are widely used, and they are an important part of flow analysis in every aspect of fluid mechanics
CFD codes are useful in the reception of valid information and data, which are used in order for new studies to be conducted, fluid behaviors to be predicted, and their applications in other fields to be developed
Ismail et al [1] studied the effects of heavy rain on the aerodynamic efficiency of cambered NACA 64-210 and symmetric NACA 0012 airfoils, concluding that both airfoils showed a significant decrease in lift and an increase in drag in simulated rain environment
Summary
It is commonly known that, in the field of fluid mechanics, CFD codes are widely used, and they are an important part of flow analysis in every aspect of fluid mechanics. Ismail et al [1] studied the effects of heavy rain on the aerodynamic efficiency of cambered NACA 64-210 and symmetric NACA 0012 airfoils, concluding that both airfoils showed a significant decrease in lift and an increase in drag in simulated rain environment. Wan et al [2] studied the effects of different liquid water contents (LWC) on airfoils in order to establish the amount of aerodynamic efficiency deterioration. They compared their results with the NASA Technical Memorandum 4420 [3], a study conducted by Bezos and Campbell about the evaluation of the rain effect on airfoil lift. Haines and Luers [4] studied the aerodynamic degradation of heavy rain on airplanes, evaluating the reasons for drag and lift penalties due to the presence of rain
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