A Study on Free Surface Effect of 2-D Airfoils

J. Ocean Eng. Technol. 1995;9(2):75-82.

Park Il-Ryong,Jeon Ho-Hwan

2차원 익형의 자유수면 효과에 관한 연구

박일룡,전호환

부산대학교 조선해양공학과 대학원,부산대학교 조선해양공학과 기계기술 연구소

Keywords: 2-D airfoil, WIG, Lift, Free surface effect, Source and vortex distribution, Wave elevation, Image method

핵심용어: 2차원 날개, 해면효과익, 양력, 자유수면효과, 소오스와 보오텍스 분포, 파고, 경상법

Abstract

The free surface effects on the aerodynamic performance of 2-D wings are investigated based on the potential flow approximation. The wing is represented b source and vortex distributions on the wing surface. The steady free surface effect is taken into account by source distribution on the free surface and the velocity potentials of air and water flows are obtained. Using three different techniques, namely, positive image method, inverse image method and source distribution method, numerical results are obtained for wave elevation, pressure distribution and lift coefficient with various foil sections. The wave elevation calculated by the inverse image method is shown to be very small even at higher speeds so that the free surface effect on the performance of wings is regraded negligible. However, the wave elevations by the positive image method and source distribution method are relatively high at higher speeds and accordingly the free surface effects on wings can not be neglected.