Experimental Investigation about Drag Force on the Both Icy and Non-icy Airfoils

Abstract

In this paper, the influence of icy boundary on the drag force is studied experimentally. For this purpose, at first, the drag force on NACA0015 airfoil is measured in a subsonic wind tunnel. The span of airfoil is 15 cm and its chord are 20 cm and the section of airfoil for experiments is 300×450 mm. Then, a cast is designed to produce icy airfoil with the same dimensions of aforementioned airfoil. The drag force of icy airfoil is measured in the same wind tunnel, too. Polyamid is used to make the cast. The results show that the drag force on the icy airfoil is up to 40 % less than non-icy one. This reduction is lower for smaller attack angles. Delayed boundary layer separation is the main reason for decrease in drag force. Sublimation of icy airfoil produces the secondary flow accompanying with a new boundary layer under the primary one. The secondary boundary layer is another reason for reduction of drag force. Experiments are conducted at different attack angles between and The Reynolds numbers are between 105 and 2.5×105. The accuracy of experimental instruments is considered and the results are obtained after numerical error analysis.