A software tool for blade design

Abstract

An interactive software tool for blade design of axial flow machines was created. It is written as an extension module to the open-source software FreeCAD. In its graphical interface, the user can modify the blade profiles, stack them to create the whole blade and generate end walls and other stage features. Or everything can be controlled by a simple Python script. Results can be saved as STEP file or STL mesh and export to a mesh generator and CFD solver. Blade profiles are given by a set of parameters describing Bézier curves, the blade is represented by b-spline surfaces. Up to now, the tool helps the designer to find the right shapes by a 1D method, which evaluates the velocity triangles and the state variables through the machine stage on a mean line (mean radius) from the given design parameters (mass flow, total states in front of the stage, rotational speed etc.) and distribute them along the radius from the hub to the tip. The CFD results of a sample designed stage are included.