Adjoint-based Shape Sensitivities for Turbomachinery Design Optimizations

An adjoint preprocess for an adjoint-based turbomachinery design process is described. The resulting process is compared to a previously established adjoint process based on three-dimensional adjoint solutions and deformed meshes. Within the new process, the calculation of sensitivities is performed using shape sensitivities and surface displacements, where the design parameters are computer-aided design (CAD) parameters describing the geometry of a turbomachinery component. In particular, an automatized process for the generation of surface displacements from variations of the CAD parameters is described. Shape sensitivities are calculated using an adjoint elliptic mesh deformation tool. The method is applied to a counterrotating fan. Integrating the adjoint preprocess into the gradient evaluation results in a significantly reduced memory usage, since no perturbed three-dimensional meshes have to be generated. It also has the potential to reduce the dependency of the computation time on the number of design parameters. Moreover, the shape sensitivities provide interesting insights into the design problem.