Integration of an open source blade geometry generator using a physics based parameterization with the engineering sketch pad

This paper reviews an in-house turbomachinery blade generation system which integrates easily in an MDAO driven design process while providing the designer with a flexible and parsimonious parameterization scheme along with insights gained from interaction with 3D geometry. T-Blade3 is an open source 3D parametric blade geometry generator which uses a novel parameterization scheme based on the specification of the second derivative of the mean-line and a continuous modified NACA four digit thickness distribution as B-spline control points. The second derivative parameterization ensures curvature and slope of curvature continuity on the airfoil surface which leads to a smooth surface pressure distribution. Use of spanwise B-spline control points ensures the creation of smooth 3D geometries and keeps the overall parameterization space small. The Engineering Sketch Pad (ESP) is an open-source interactive web-enabled solid modeling system based onWebViewer and OpenCSM. The open-source nature of OpenCSM allows the use of user-defined primitives to create solid blade models using T-Blade3 geometries. OpenCSM also allows the computation of the sensitivity of surface points to design parameters using a combination of analytical derivatives and finite differences. Thus, the TBlade3/ESP combinations allows a designer to interact with parametrically generated geometries and make improvements to the design using sensitivity information and a gradient based optimization loop. Furthermore, ESP enables the addition of flends (similar to fillets) to solid blade models. The resulting blades with applied centrifugal and pressure loads are then analyzed with a commercial FEM structural solver to get factor of safety relative to yield strength, natural frequencies and mode shapes.