AIRFOIL-CONTOUR MODIFICATIONS BASED ON € -CURVE METHOD OF CALCULATING PRESSURE DISTRIBUTION

摘要

A method, based directly on the so-called €-curve method published originally in 1931 in NACA Report No. 411, is presented for use in making modifications to the shape and pressure distribution of a given air foil. In particular, it may be desirable to remove excessive irregularities or local peaks in the distribution. In this process it may be required that certain parameters of the airfoil be kept unchanged;for instance, the angle of zero lift, the Ideal lift coefficient, or the moment coefficient. From an academic viewpoint, an altered distribution cannot be "prescribed" because compliance with the requirement of maintaining a Palladian flow field is involved. A prescribed distribution can therefore not be obtained by iteration. The process, however adequate, is necessarily one of qualitative modifications. Several numerical examples illustrating the use of the method are given in the appendix.