Enhancement of gust using jet at trailing edge of airfoil: A novel technique

Sudden and sharp change in flow velocity, termed as a gust, is an important parameter to study flight performance, especially of micro-air vehicles (MAVs) and aircraft. There have been several techniques to create gusts in a wind tunnel including using pitching foils at the entrance of the test section. One conventional method is using two airfoils with a certain spacing to create a gust. The model aircraft to be tested is placed downstream between the pitching foils. The main limitation with this technique is the low gust intensity (Ig) that can be achieved. We propose a new method to enhance Ig using jet at the trailing edge of the pitching foils. Numerical simulation shows the gust intensity, using the proposed method, to increase by 2-7 times compared to that by conventional techniques for a particular Re, jet velocity and the range of reduced frequencies considered. Moreover, the spacing of foils ensures shear-free smooth flow in the near region surrounding the model, unlike some existing methods for gust enhancement. This technique provides a simple, economical and controlled way to study gust response of MAVs and aircraft in wind tunnels.