The Aerodynamic Effects of Distributed Propulsion on the Performance of a UAV Wing

Abstract

This study explores the aerodynamic performance of a wing and propeller system through experiments and numerical simulations. Three configurations, including a single tip propeller and four distributed propellers with the same or alternative rotational directions, are tested. The findings demonstrate that the distributed propulsion technique enhances wing performance by generating higher lift but may also increase drag and reduce cruising efficiency. The effects of propeller slipstream on pressure distribution, lift distribution, and boundary layer separation are analyzed, providing insights into the underlying mechanisms. The presence of a single tip propeller improves overall performance, whereas four propellers distributed in front of the leading edge delay stall and enhance the lift-to-drag ratio at high angles of attack. At these high angles of attack, an interesting phenomenon occurs in which the propeller slipstream is deflected upward toward the upper surface of the wing. This upward deflection of the slipstream plays a crucial role in suppressing separation of the boundary layer above the wing. This phenomenon effectively delays stall and significantly enhances the overall aerodynamic performance of the wing. This study provides valuable insights into the aerodynamic performance of unmanned aerial vehicle (UAV) wings using distributed propulsion (DP). The findings demonstrate that a DP system, in which multiple small propellers are strategically placed along the leading edge of the wing, significantly enhances lift and delays stall, particularly at high angles of attack. This configuration proves highly beneficial for UAVs that require high lift and stability during critical flight phases such as takeoff, landing, and low-speed flight operations. This study also identifies the following trade-off: whereas the DP system offers enhanced lift and improved control during these phases, the result may be increased drag and reduced efficiency during cruising, affecting overall flight range and endurance. The insights gained from this study can inform future designs of UAVs for specific uses such as cargo delivery, surveillance, and agricultural monitoring. Additionally, the results can aid in developing new aircraft models, such as air taxis, for which enhanced lift, reduced noise, and improved performance in particular phases of flight are critical for urban air mobility solutions.