MATHEMATICAL MODEL TO DESCRIBE DOUBLE CIRCULAR ARC AND MULTIPLE CIRCULAR ARC COMPRESSOR BLADING PROFILES

For the past seven decades, a compressor aerodynamicist has developed various methodologies to design, analyze, and simulate compressor stages. In compressor design, three major subsequent steps can be identified: the one-dimensional meanline methodology, the two-dimensional through-flow analysis, and the three dimensional computational fluid dynamics. One of the interconnecting threads, between these various x-dimensional analysis, is the compressor blade profile shape. This shape, of known and controllable geometric parameters, is usually accompanied by, or related to, loss models and known flow physics, either defined by theory or through experimental test. In this paper, a novel mathematical approach is described to define axial compressor airfoil profile shapes. These shapes, developed in a Cartesian coordinate system, can be used to create Double Circular Arc, Multiple Circular Arc, and a hybrid combination of the two types. The proposed methodology, based on the mathematics of circles, can be easily applied using generalized software such as Python or MATLAB, or be embedded in specialized engineering design software. In doing so, researchers and engineers can create compressor airfoil shapes which are consistent and flexible with respect to geometric parameter manipulation. Full details of the formulas, with respect to the camber line definition and the calculation of the profile intrados and extrados, are presented. A URL link to an equivalent MATLAB code, and a specialized engineering software, has been provided for those researchers that wish to apply the formulations and review its use.