Continuous Modified NACA Four-Digit Thickness Distribution for Turbomachinery Geometries

A study describes a novel thickness distribution, implemented in T-Blade3, based on the modified NACA four-digit thickness and its application to three turbomachinery geometries. The modified NACA four-digit thickness definition consists of modifications made to the leading-edge (LE) radius and the location of the maximum thickness. In this study, all thickness parameters are continuous and not restricted to being integers. Modifications have been made to allow specification of the trailing edge (TE) thickness and the first derivative of the TE thickness, which allows for the addition of a circular TE to the blade section. These modifications give rise to a geometry generation method that has been specifically developed to work with turbomachinery geometries while possessing all the desirable characteristics of a geometry generator. Additionally, the importance of control over a round LE for developing smooth flow over blades and improving incidence tolerance has been demonstrated in the study.