Compatible isogeometric analysis algorithm for three kinds of impeller models

Turbojet engines played significant roles in the aviation industry and still have important applications in small engines for missiles to reduce weight. In this paper, we concentrate on the simulation of the centrifugal turbine impeller and introduce the advanced Isogeometric analysis (IGA) method. IGA, which bypasses the mesh generation process in finite element analysis (FEA), has the potential for seamless integration between computer-aided design (CAD) and computer-aided engineering (CAE). To overcome the problem of only applying the spline basis function in IGA, we propose a parametric modeling approach and construct a centrifugal impeller library. The proposed modeling method generates a compatible hub by rotating the customized shaped blades, avoids the trimmed curves and surfaces, and provides suitable analysis models straight for IGA. The constructed library produces three distinct centrifugal impellers, which are represented by multiple non-uniform rational B-splines (NURBS) patches, including Reissner-Mindlin (RM) shell-to-RM shell, RM shell-to-solid, and solid-to-solid. To avoid the instability issues arising from weakly gluing algorithms in the analysis process on complex geometries, we propose an effective coupling method utilizing compatible patches to globally number the control points and assemble the stiffness matrix and load vector. The degree of freedom (DOF) of the solid is employed to dispose of the inconsistent DOF problem between the RM shell-to-solid model in this algorithm. We consider two kinds of operating environments, including centrifugal force and steady heat conduction to the functioning turboprop. Under the same accuracy, our MATLAB coding results demonstrate that IGA requires fewer elements, and achieves superior rendering effects to ABAQUS. Unlike FEA, the IGA method maintains the same geometry as the origin model after analysis.