Wing-Induced Integration Effects on Propeller Performance in a Distributed Propulsion Configuration

The interaction between propeller and wing in distributed propulsion configurations has a significant impact on system efficiency and performance. This study investigates these interactions using a large scale wind tunnel model at 0.3 < J < 1 at the Propulsion Test Facility of TU Braunschweig. The setup consists of a modified NACA 63(2)415 profile wing c = 0.8m and three propellers D = 0.6m in front of the wing. Time averaged static pressures and fast response pressure transducers in combination with a 6K balance for each wing and propeller provide detailed measurements. The focus of this study is the influence of the wing on the propeller. The results show, that propeller placement variations affect the propeller performance. In particular, below the wing propeller positions show higher thrust at constant operating conditions compared to the reference isolated propeller, due to differences in local velocities caused by the circulation of the wing. Steady-state and transient data show that as the advance ratio decreases, the propeller's absolute influence increases and local flow conditions change. However, when using the global advance ratio, deviations occur. On the one hand, this is crucial for the design of propeller blades, which are commonly designed in isolated conditions. According to the position of the installed propeller, the operating point and it's optimum deviates from the design point. On the other hand, with the standard definition of propeller efficiency, using the global freestream velocity, unphysical efficiencies can be obtained. For isolated consideration of the installed propeller this definition must therefore be carried out with the local inflow velocity. These findings will guide future system design adjustments in distributed propulsion configurations, taking into account propeller-wing interactions.