Design and experimental investigation with particle image velocimetry of a minimum induced drag wing

In order to fly, an aircraft of a given weight needs to produce an equal but opposite force to this weight: the lift. This lift generation comes along with an induced drag creation. In fact, when flying, an aircraft leaves behind itself a pair of counter-rotating vortices, which are intrinsically linked to the induced drag, as we will see later on in this document. In order to compute this aerodynamic characteristic, Ludwig Prandtl published in 1922 a model famously known as the "Lifting line theory". Resulting from this theory, the wing which offered the best performances (the minimum ratio of lift per drag production) had an elliptical spanload. This quickly became the reference in the design of wings but, in 1933, Prandtl himself stated that his former theory was incomplete. In fact, this concept only took the performances of the wing into consideration, but did not refer to its structural mass. Prandtl therefore published a note where he explained that the best new spanload was bell-shaped. In addition to the structural mass consideration, this type of wing would produce 11 percent less induced drag than an elliptical wing. This is a major statement that NASA investigated back in 2015, by creating a so called Prandtl-D Aircraft, designed on the Prandtl’s theory. The purpose of this Masters’ thesis is, like NASA did, to design, manufacture and test our own bell-shaped wing in order to investigate the expected aerodynamic characteristics presented here above