ABSTRACT
The transformation of Joukowski is presented. The calculations of lift force on air foil are developed. The theorem of Kutta-Joukowski is introduced.
1 PRESENTATION
In the previous chapter, the horizontal flow past a circular arc and a Joukowski airfoil was presented (Chap. I-5, sections 3.6 & 3.7). In each case, there was no circulation in the z-diagram and the lift force on the object was zero. This approximation is incorrect in practice. Some lift is experienced on the airfoil and circular arc, more generally on any profile that is not symmetrically formed or situated with respect to the flow direction. Physically this is related to the flow next to the trailing edge of the airfoil or arc (Fig. 6.1). In absence of circulation, a stagnation point is observed on the nose and on the upper surface next to the trailing edge (Fig. 6.1A). At the rear end, the velocity is non-zero and the cusp of the trailing edge induces a discontinuity in terms of velocity. That is, the trailing edge is a singularity.
