• Journal of Ocean Engineering and Technology
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• v.11 no.1
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• pp.55-64
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• 1997

A wing operating in close proximity to the ground exhibits a reduction in induced drag, which increase the lift/drag ratio. The poert-augmented ram (RAR) phenomenon involves directiing the efflux from forward mounted propulsion ststem under the wings, with the efflux nearly stagnated under the wings. In the present paper, 3 dimentional PAR was numerically studied by solving the Navier-Stokes equations. Pressure distribution and velocity vectors are calculated around the wing surface and the ground. Through the numerical simulation, Cp values and lift/drag ratio are carefully reviewed by changing the height/chord; 0.05, 0.1, 0.3 and 0.8. The shape of model is NACA 0012 with a span/chord ratio of 3.0. According to the numerical results, the relationship between lift/drag and height/chord is fairly reasonable.

• Journal of the Society of Naval Architects of Korea
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• v.37 no.3
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• pp.57-68
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• 2000

The Power Augmented Ram(PAR) effect, which blows the down stream of the propellers into the underside of the wings and hence increases the pressure between the lower surface of the wings and the sea surface, is known significantly to enhance the performance of the WIG concept by reducing the take-off and landing speeds. The aerodynamic characteristics of a 20 passenger PARWIG are investigated by wind tunnel tests with the 1/20 scale model. The efflux of the forward mounted propellers are simulated by jet flows with a blower and duct system. The lift, drag, and pitch moment of the model with various ground clearances, angles of attack and flap angles are measured for the various jet velocities, jet nozzle angles, horizontal and vertical positions of the nozzle, and the nozzle diameters. The aerodynamic characteristics of the PARWIG due to these parametric changes are compared and pertinent discussions are included. It is shown that the proper use of the PAR can increase the lift coefficient of as much as up to 4.

• Journal of Ocean Engineering and Technology
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• v.12 no.2 s.28
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• pp.79-86
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• 1998

A three-dimensional WIG (Wing In Ground effect) moving above free surface is numerically studied by means of finite difference techniques. The air flow field around the WIG is analyzed by MAC (Marker & Cell) method, and interactions between WIG and the free surface are appeared as the variation of pressure distribution acting on the free surface. To analyze the wavemaking phenomena by those pressure distributions, the NS (Navier-Stokes) solver is employed in which nonlinearities of the free surface conditions can be included. Through the numerical simulation, Cp values and lift/drag ratio are carefully reviewed by changing the height/chord ratio. The section shape of model is NACA0012 with the span/chord ratio of 3.0. Through computational results, it is confirmed that the effect of free surface is small enough to treat it as a rigid wavy wall.

• Journal of Mechanical Science and Technology
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• v.15 no.3
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• pp.384-391
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• 2001

The aerodynamic effects of a 3-dimensional Wing in Ground Effect (WIG) which moves above the free surface has been numerically investigated via finite difference techniques. The air flow field around a WIG is analyzed by a Marker & Cell (MAC) based method, and the interactions between WIG and the free surface are studied by the pressure distributions on the free surface. Waves are generated by the surface pressure distribution, and a Navier-Stokes solver has been employed, to include the nonlinearities in the free surface conditions. The pressure values Cp and lift/drag ratio are reviewed by changing the height/chord ratio. In the present computations a NACA0012 airfoil with a span/chord ratio of 3.0 are treated. Through computational results, it is confirmed that the free surface can be treated as a rigid wavy wall.