A differentiated geometry blade parameterization methodology for gas turbines

The present paper is about the turbomachinery blade geometry parameterization, which has been developed at the DLR Institute of Propulsion Technology for the last two decades. It was implemented into the software BladeGen, which is used to design blades and vanes for axial and radial compressors as well as for fans, propellers and turbines. The parameterization uses typical geometric variables such as characteristic angles and lengths in combination with B-spline parameters like control points and knot vectors to generate a variable number of two-dimensional profile-sections, which are transformed by a conformal mapping into three-dimensional space and connected via NURBS surfaces to form blade surfaces and solids. This publication presents the application philosophy and some parameterization and implementation details. The intuitive handling and some software enhancements such as algorithmic differentiation capabilities are also demonstrated by application examples.