Aerodynamic characteristics of wing are highly influenced by its proximity to any other surface such as ground or ceiling. Traditionally the phenomenon of Wing-In-Ground (WIG) effect is widely explored and reported. However, the effect of ceiling is rarely looked at. Thus, present work is intended to investigate the aerodynamic performance of Wing-In-Ceiling (WIC) effect, i.e. when the surface is from suction side of the wing. The results are reported for the effect of range of Reynolds numbers, ceiling clearances and angles of attack on the measured aerodynamic coefficients and aerodynamic efficiency from experiments. Additionally, CFD studies are carried out to investigate the effect of ground and ceiling proximity on velocity and pressure distribution over the wing and the same is compared with corresponding out of ceiling conditions.
The present work entails aerodynamic investigations of ceiling effect, addressing specific issues like a) 3D analysis of a finite rectangular wing, b) Use of both experiments and computational analysis and c) Operating at low Reynolds numbers at pre- and post-stall angles of attack. The rectangular wing, aspect ratio, AR = 6.4 used in the present work has a symmetric airfoil section, NACA0012 and is studied at different ranges of ground and ceiling proximity. Unsteady and time-averaged six-component aerodynamic characteristics, coefficients of Lift, Drag, Side forces, Pitch, Roll, Yaw moments at several angles of attack are reported. Effect of ground/ceiling proximity on the occurrence of stall and CLmax is studied. Numerical calculations using steady-state CFD are also made for quantitative comparison and flow visualization to investigate the effect of airfoil shape and aspect ratio. The effect of ground/ceiling proximity on the span-wise pressure distribution and induced velocity in the vicinity of the wing is also discussed in detail.