Research Fellows

Ilias Vasilopoulos

Early Stage Researcher 11 at Rolls-Royce Deutschland

• Research
• Outreach
• Biography

• Overview
• Publications
• Design Velocity Approach
• CAD-based Optimization
• CAD-free Optimization
• Experimental Validation
• Algorithmic Differentiation
• Mesh Morpher

The aim of this research project was to evaluate different approaches to CAD-free and CAD-based aerodynamic optimization for the intended application on geometrically complex turbomachinery components. This has been achieved throughout the course of the project in two main steps. First, different approaches proposed by the academic partners of this project have been evaluated and tested in industrial test cases throughout extensive collaborations. Then, the most promising of them were selected and implemented into the Rolls-Royce Deutschland (RRD) process chain, which mainly comprises of in-house tools such as the CAD parameterization software Parablading, the meshing tool PADRAM and the HYDRA primal and adjoint solvers. The developed process has been applied to the aerodynamic optimization of industrial turbomachinery components, while also addressing the challenging aspects that arise, namely (i) the automation of the workflow, and (ii) the imposition of geometric design constraints. Demonstration of the developed process chain has been accomplished on the TU Berlin TurboLab Stator benchmark test case and the final optimum stator was manufactured and measured in a wind-tunnel. The results obtained from this research project have been published in terms of 3 conference papers, 2 conference talks and 1 joint journal article. It can be concluded that the interaction between industry and academia has been very successful and provided useful knowledge and developments for both sides.

Achievements

• The RRD in-house mesh morpher which uses the linear elasticity approach was enhanced by incorporating constraints into the deformation. More specifically, for turbomachinery applications, a radius constraint was introduced at the hub region and a sliding mesh capability was implemented for the casing.
• In collaboration with Dheeraj Agarwal (ESR 10), CAD derivatives through finite-differencing (FD) were computed for two test cases of increased geometric complexity provided by RRD. Parametric sensitivities were obtained by linking the RRD adjoint sensitivity maps with the QUB design velocities. These were validated against FD results and good agreement was shown. The results of this work were published in [1, 3].
• A similar FD approach was implemented in the RRD process chain and, thus, an automated CAD-based aerodynamic optimization workflow was developed and demonstrated (deliverable 28 D6.2). The first results were presented in [2] and, later, an improved workflow was published in [4].
• In collaboration with Mladen Banovic (ESR 12), the algorithmic differentiation (AD) approach developed in UPB was employed to partially differentiate the RRD in-house aerofoil design tool. The differentiated code was validated against FD and an improved CAD-based optimization process chain was demonstrated.
• In addition, a CAD-free aerodynamic optimization framework was implemented, which incorporated the implicit smoothing approach developed by Pavlos Alexias (ESR 4). Its applicability was tested on the TU Berlin Stator case and a comparison was made against the CAD-based result. This comparison was presented in [5].
• The final optimum TU Berlin Stator was manufactured using 3D printing technology and measured in an open circuit wind tunnel at the Chair for Aero Engines of the TU Berlin. This experimental validation was published in [6].