Effects of leading-edge geometry on aerodynamic performance in controlled diffusion airfoil

Class function/shape function transformation technique(CST) was improved and used to design the leading edge of the controlled diffusion airfoils. This method removes the leading edge curvature discontinuities, eliminates the leading-edge spikes under the design states, and then improves the aerodynamic performance significantly. Different leading-edge shapes with no curvature discontinuities were achieved using different shape function. Although they have the same minimum loss, the available incidence range is quite different. Studies show that it is caused by the different development process of the leading edge spikes under the off-design conditions. Too large spikes could thicken the early suction surface boundary layer rapidly or even cause premature transition.