Effect of Endplate Shape on Performance and Stability of Wings-in Ground (WIG) Craft

Authors: Kyoungwoo Park, Chol Ho Hong, Kwang Soo Kim, Juhee Lee

Abstract:

Numerical analysis for the aerodynamic characteristics of the WIG (wing-in ground effect) craft with highly cambered and aspect ratio of one is performed to predict the ground effect for the case of with- and without- lower-extension endplate. The analysis is included varying angles of attack from 0 to10 deg. and ground clearances from 5% of chord to 50%. Due to the ground effect, the lift by rising in pressure on the lower surface is increased and the influence of wing-tip vortices is decreased. These two significant effects improve the lift-drag ratio. On the other hand, the endplate prevents the high-pressure air escaping from the air cushion at the wing tip and causes to increase the lift and lift-drag ratio further. It is found from the visualization of computation results that two wing-tip vortices are generated from each surface of the wing tip and their strength are weak and diminished rapidly. Irodov-s criteria are also evaluated to investigate the static height stability. The comparison of Irodov-s criteria shows that the endplate improves the deviation of the static height stability with respect to pitch angles and heights. As the results, the endplate can improve the aerodynamic characteristics and static height stability of wings in ground effect, simultaneously.

Keywords: WIG craft, Endplate, Ground Effect, Aerodynamics, CFD, Lift-drag ratio, Static height stability.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1328792

References:

[1] http://www.se-technology.com.
[2] C. Wieselsberger, "Wing Resistance near the Ground," NACA TM No. 77, 1922.
[3] M.P. Fink and J.L. Lastinger, "Aerodynamic Characteristics of Low-Aspect-Ratio Wings in Close Proximity to the Ground," NASA TN D-926, 1961.
[4] A.W. Carter, "Effect of Ground Proximity on the Aerodynamic Characteristics of Aspect-Ratio-1 Airfoils with and without End Plate," NASA TN D-970, 1961.
[5] M. R. Ahmed, "Aerodynamics of a NACA4412 Airfoil in Ground Effect," AIAA Journal, Vol. 45, No. 1, 2007.
[6] C. Hsiun and C. Chen, "Aerodynamic Characteristics of a Two-Dimensional Airfoil with Ground Effect," J. of Aircraft, Vol. 33, No. 2, 1996.
[7] W. Rodi, Turbulence models and their applications in hydraulics-a state art of review, Book Publication of International Association for Hydraulic Research, Delft, Netherlands, 1984.
[8] L. H. Norris and W. C. Reynolds, Turbulent Channel Flow with a Moving Wavy Boundary, Report. FM-10, Department of Mechanical Engineering, Stanford University, CA, 1975.
[9] STAR-CD v4.00, Methodology, Computational Dynamics, Co., London. U. K, 2006.
[10] S.V. Patankar, Numerical Heat Transfer and Fluid Flow, McGraw-Hill Book Company, New York.
[11] Chang-Yeol Joh and Yang-Joon Kim, "Computational Aerodynamic Analysis of Airfoil for WIG (Wing-In-Ground-Effect) - Craft," JSAS, Vol. 32, No. 8 (Korean), 2004.
[12] M. R. Ahmed and S.D. Sharma, "An investigation on the aerodynamics of a symmetrical airfoil in ground effect," Experimental Thermal and Fluid Science, Vol. 29, pp. 633-647, 2005.
[13] N. A. Ahmed, and J. Goonaratne, "Lift Augmentation of a Low-Aspect-Ratio Thick Wing in Ground Effect," J. Aircraft, Vol. 39, No. 2, 2002.
[14] I.G. Recant, "Wing-Tunnel Investitation of Ground Effect on Wing with Flaps," NACA TN No. 705, 1939.
[15] R.D. Irodov, "Criteria of Longitudinal Stability of Ekranoplan," Ucheniye Zapiski TSAGI, Vol. 1, No. 4, 1970.