Node-Based Adjoint Surface Optimization of U-Bend Duct for Pressure Loss Reduction

The pressure loss reduction inside the U-bends of internal cooling channels is of crucial importance to increase the performance of cooling systems of gas turbines. The optimization technique proposed in the present work is based on the continuous adjoint shape method and is implemented in the OpenFOAM open-source framework. The calculated gradients of the objective function are linked to a node-based constrained morphing routine, allowing the modification of the shape towards an optimum design with minimal pressure loss. The integration with a robust mesh morpher solver leads to successive automatic steps towards the design improvement. Design modifications take into account constraints and limitations related to the chosen design. The feasibility of the design is guaranteed by the application of a smoothing function with the aim to avoid rough external surfaces.