AN INVESTIGATION INTO WING IN GROUND EFFECT AIRFOIL GEOMETRY

The present paper investigates the aerodynamic characteristics of an arbitrary airfoil and its impact on the performance of a Ground Effect Vehicle GEV. The approaches that have been previously suggested and conducted for studying the WIG problem are demonstrated. Few published papers are accompanied by reasonable background information to enable an independent researcher to directly incorporate the available mathematical model into his calculations. A numerical technique for investigating the aerodynamic characteristics of an arbitrary airfoil in the ground effect zone is adapted. Wide ranges of the dominant parameters, i.e., ground clearance, angle of attack and Reynolds number are considered. The calculations are performed within the framework of a 2-D formulation to provide a simple mathematical model with a meaningful physical interpretation of the numerical results. Prominence is given to the investigation of the numerical results and there physical interpretation rather than ...

2009

The Prediction of aerodynamic characteristics and shape optimization of airfoil under the ground effect have been carried out by integration of computational fluid dynamics and the multiobjective Pareto-based genetic algorithm. The main flow characteristics around an airfoil of WIG craft are lift force, lift-to-drag ratio and static height stability (H.S). However, they show a strong trade-off phenomenon so that it is not easy to satisfy the design requirements simultaneously. This difficulty can be resolved by the optimal design. The above mentioned three characteristics are chosen as the objective functions and NACA0015 airfoil is considered as a baseline model in the present study. The profile of airfoil is constructed by Bezier curves with fourteen control points and these control points are adopted as the design variables. For multi-objective optimization problems, the optimal solutions are not unique but a set of non-dominated optima and they are called Pareto frontiers or Par...

Experimental Thermal and Fluid Science, 2005

The flow characteristics over a symmetrical airfoil--NACA 0015--are studied experimentally in a low speed wind tunnel. The pressure distribution on the airfoil surface was obtained, lift and drag forces were measured and mean velocity profiles were obtained over the surface. The wake region was also explored in detail and measurements of mean velocity and turbulence intensities were performed at two stations downstream of the trailing edge. Experiments were carried out by varying the angle of attack, a, from 0°to 10°and ground clearance of the trailing edge from the minimum possible value to one chord length. It was found that high values of pressure coefficient are obtained on the lower surface when the airfoil is close to the ground. This region of high pressure extended almost over the entire lower surface for higher angles of attack. As a result, higher values of lift coefficient are obtained when the airfoil is close to the ground. The flow accelerates over the airfoil due to flow diversion from the lower side, and a higher mean velocity is observed near the suction peak location. The pressure distribution on the upper surface did not change significantly with ground clearance for higher angles of attack. The upper surface suction causes an adverse pressure gradient especially for higher angles of attack, resulting in rapid decay of kinetic energy over the upper surface, leading to a thicker wake and higher turbulence level and hence a higher drag. The lift was found to drop at lower angles of attack at some values of ground clearance due to suction effect on the lower surface as the result of formation of a convergent-divergent passage between the airfoil and the ground plate. For the angle of attack of 12.5°, a very thick wake region was observed and higher values of turbulence intensity were recorded.

The software algorithm WIGFOIL has been developed for the rapid and reliable modeling of airfoils in close proximity to the ground. The method is based on a second order inviscid vortex potential flow method and corrected for viscous effects by means of the displacement thickness viscous-inviscid iterative concept. The viscous correction is based on a number of empirical correlations and a two equation integral formulation. A mirror image vortex panel distribution is utilized to simulate ground effect.

buet.ac.bd

The paper numerically investigated the flow characteristics over a compound wing during ground effect. The compound wing is divided into three parts where one rectangular wing in the middle and two taper reverse wings with negative dihedral angle in sides. The NACA6409 airfoil was employed as section of wings. Three dimensional (3D) Computational Fluid Dynamic (CFD) was applied as a computational scheme. The k-ε turbulent model was utilized for characterization of flow over wing surface. The computational results of a rectangular wing with aspect ratio 1.5 and angle of attack 2º with different ground clearance were compared with experimental data of published work. Next, the principal aerodynamic characters of compound wing and a rectangular wing were computed for various ground clearance. The numerical results of CFD simulation of compound wing were compared with the rectangular wing and have an acceptable improvement in lift and drag ratio, although its stability a little reduced. The major modification of lift to drag ratio of compound wing occurs at extreme ground effect.

Detailed Report on the Graduation Project related to the design and fabrication of the WIG craft

The Scientific World Journal, 2014

The aerodynamic characteristics of the wing-in-ground effect (WIG) craft model that has a noble configuration of a compound wing was experimentally investigated and Universiti Teknologi Malaysia (UTM) wind tunnel with and without endplates. Lift and drag forces, pitching moment coefficients, and the centre of pressure were measured with respect to the ground clearance and the wing angle of attack. The ground effect and the existence of the endplates increase the wing lift-to-drag ratio at low ground clearance. The results of this research work show new proposed design of the WIG craft with compound wing and endplates, which can clearly increase the aerodynamic efficiency without compromising the longitudinal stability. The use of WIG craft is representing an ambitious technology that will help in reducing time, effort, and money of the conventional marine transportation in the future.

Abstract—The performance and environmental impact of a new compound wing were numerically investigated in proximity to the ground. The compound wing was divided into three parts where one rectangular wing in the middle and two reverse taper wings with anhedral angle on sides. Three dimensional (3D) computational fluid dynamics (CFD) was employed for numerical simulation. The k-ε turbulent model was applied for current flow over wing surface. The NACA6409 airfoil was used as a wing section.

Ocean Engineering, 2018

The ground viscous effect is an objective that could be an essential parameter for the conceptual design of wingin-ground effect (WIG) crafts. This study numerically investigates the effect of ground boundary layers on the aerodynamics of a compound wing of a WIG craft. Computational simulations were conducted to evaluate various design parameters such as middle span size, anhedral angle and taper ratio. The flow structure in the physical domain around the wing surface was demonstrated with a realizable k-ε turbulent model. The numerical results of the compound wing for a fixed ground boundary condition were then further validated using experimental data from the wind tunnel. The principal aerodynamic coefficients of compound wings were achieved for both fixed and moving ground conditions. The numerical simulations demonstrated that the ground viscous effect of fixed ground has some effects on lift and drag coefficients and lift-to-drag ratio, including a reduction in the lift coefficient and an increase in the drag coefficient compared with the moving ground. However, the design parameters had a different impact on the ground viscous effect. Nevertheless, the results are predicted to be able to provide a more fine-grained understanding on the ground viscous effect on WIG craft.

A numerical investigation is performed to study aerodynamics of a 2D NACA0012 wing and flows in ground effect(IGE).Lift and drag forces are obtained and pressure distribution on airfoil surfaces is recorded at different angles of attack and ground clearances.Viscous flow near ground and air compressibility are taken into account.High lift is obtained as the airfoil is in close proximity to the ground.The stall angle decreases with reduction of the ground clearance,due to higher adverse pressure gradient.Viscous effect of floor shows less effect on airfoil.Compressibility should be taken into account at lower ground clearances.