Extension of a CFD-CSM Toolchain for Simulating the Wing of a Regional Aircraft with Distributed Propulsion Employing an Actuator Disk Model

Abstract

The present thesis investigates fluid-structure interaction (FSI) and propeller interference effects for a wing of a multi-propeller regional aircraft by conducting high-fidelity multidisciplinary simulations employing the actuator disk model. For that, a software extension is implemented which integrates the existing actuator disk model of DLR's (German Aerospace Center) flow solver TAU into a coupled simulation involving fluid dynamics and structural mechanics solvers (CFD-CSM). With the transition towards a more climate-compatible aviation, the aerospace industry faces a major challenge in the upcoming decades. Confronting this challenge, the EU funds large research projects such as HERA. HERA's goal is to develop and assess novel architectures for propeller aircraft with hybrid propulsion. One of its projected tasks is to advance current modeling capabilities for these types of aircraft. Reynolds-averaged Navier Stokes (RANS) analyses are a well-established simulation technique. In combination with the actuator disk model they provide an accurate and cost-effective solution for simulating propeller-wing aerodynamics. The use of lightweight materials and improved manufacturing techniques enable more slender and flexible wing designs, making them more aerodynamic but also more susceptible to FSI effects. This challenges the limits of monodisciplinary Computational Fluid Dynamics (CFD) analysis; coupled CFD-CSM simulations are, however, able to take FSI effects into account. The FlowSimulator suite has been developed in a joint effort by Airbus, ONERA, and DLR to create a software framework for multi-disciplinary simulations. While the flow solver TAU includes an AD model, it has not been integrated and applied in FlowSimulator-based CFD-CSM simulations. Therefore, this thesis implemented a software module which creates an appropriate interface for the AD model, allowing it to be used in multi-disciplinary simulations for the first time. With that, a series of coupled CFD-CSM analyses of a HERA use case are conducted. The analyses investigate FSI and propeller interference effects on the wing and assess the influence of several wing and propeller parameters on aerodynamic performance on the basis of multiple design variations. The results show the significance of wing flexibility and propeller-wing interaction effects which depend on the combined influence of various interrelated design parameters. The CFD meshes needed for the different designs are created using an automated mesh generation process based on a parametric CAD model. In preparation for a future application in multidisciplinary optimisation (MDO) scenarios, the AD-integrated process is tested under high loads and extreme parameters, confirming its robustness for large deformations and a wide range of parameter inputs. With this thesis, an important capability for the multidisciplinary analysis of propeller aircraft is established. Advanced modeling techniques, which can take both the fluid and the structural domain into account, are key in identifying more efficient but also feasible designs. In the future, the developed workflow can be expanded and used for trade-off studies or integrated into MDO toolchains, enhancing the development of novel propeller aircraft architectures.