Interference effects on wing with tilting and lifting propeller arrangement

• Applicant: Professor Dr.-Ing. Christian Breitsamter
• Subject Area: Fluid Mechanics
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 568155944

In recent years, a wide range of configuration variants have been proposed for the application area of "Urban Air Mobility" using "electrical Vertical Take-Off and Landing" (eVTOL) configurations. The development of eVTOL aircraft of various payload classes for the transport of goods and people is being driven forward worldwide. Some are already in the phase of flight testing and demonstration in terms of certification requirements. The propulsion and lift generation functions can be implemented using combined propeller/rotor arrangements, e.g. tiltable propulsion and fixed lifting propellers. In the present project, aerodynamic data and propeller-specific quantities are to be analyzed for a generic wing configuration with pylon stations that carry a tilting propeller in front of the wing and a lifting propeller behind it. The main goal is to deepen the understanding of the flow patterns in the interaction of axially and laterally staggered tilting and lifting propellers in relation to the transition from hover to forward flight and their connection with the aerodynamic properties and stability characteristics. For this purpose, complementary experimental and numerical simulations are conducted. In wind tunnel tests, forces, moments, pressure distributions and flow fields are recorded in time accurate manner on a representative scaled model. Based on these results, calculations applying Reynolds-averaged Navier-Stokes methods and partially scale-resolving methods are validated dedicated to a comprehensive analysis possible by combining the experimental and numerical data. The analysis is intended to shed light on the interference effects that prevail when tilting and lifting propellers are combined with lift-generating surfaces and having a significant influence on the aerodynamic properties and longitudinal stability of such a wing-propeller configuration. Of particular importance are unsteady aerodynamic loads with regard to fluctuation intensity and frequency-specific content that arise when there is a pronounced oblique inflow on the propeller, interacting with the wing flow and interfering with downstream propellers. The flow separation scenarios under the influence of interfering propeller flows are of particular relevance for safe flight operations. Well-controlled flight maneuvers are an indispensable prerequisite, particularly, for operations in densely populated areas and demanding approach and departure scenarios. The project thus results in a comprehensive database in the sense of basic research that reveals the properties of tilting/lifting propeller arrangements, especially, taking into account the special flow situations at high angles of attack.

• DFG Programme: Research Grants